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w$ltH l¡{sïlï[rrgLIßR,,,{"RT
THE POTENTIAL OF CEREAL.LEGUME
MIXTURES AS FORAGE CROPS
by
Sartaj Khan, M.Sc. Hons. (Peshawar, Pakistan)
A thesis submitted to the University of Adelaide
in fulfilment of ttre requirements for the degree
of Master of Agricultural Science
Deparrnent of Plant Science
Waite Agricultural Research Institute
The University of Adelaide
11r' to'ct
Y()
April, 1991
(ü)
TABLE OF CONTENTS
Abstract
Statement
Acknowledgements
List of figures
List of tables
List of plates
List of appendices
GENERAL INTRODUCTIONAims of the thesis research
Site of experiments
2 LITERATURE REVIEW
Constraints to forage production in Mediterranean
environments
Background to mixed croPPing
Competition and yield advantages
Biological basis for mixed cropping advantages
Use of cereals and legumes for forage production in
pure stands and mixtures
Effects of sowing rates on herbage and grain yields of
forage crops
Effects of nitrogen fertilizer on herbage and grain
yields of forage crops
Effects of grassÂegume mixture on protein yield
2.1
2.2
2.3
2.4
2.5
2.6
Page No.
(vüi)
(ix)
(x)
(xi)
(xviii)
(xix)
5
9
10
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(v)
1
1.1
1,.2
I4
4
6
16
t9
22
26
2.7
2.8
(üi)
3 EXPERIMENTAL3.1 Experiment l: The potential productivity of some barley,
oats, triticale and vetch species as forage crops
3. 1. 1 Introduction
3.t.2 Maærials and methods
3.1.2.1 Data collection
3.1.3 Results
3.1.3. 1 Plant establishment
3.1.3.2 Drymatæryield
3.1.3.3 Flowering
3.1.3.4 Crude protein percentage
3 . 1 .3 .5 Crude protein yield
3.1.4 Discussion
3.2 Experiment 2t The effects of sowing rate on yield
and protein content of oats, medic and vetch
forage crops
3.2.1 Introduction
3.2.2 Materials andmethods
3.2.2.1 Data collection
3.2.3 Results
3.2.3.L General
3.2.3.2 Plant establishment
3.3.3.3 Drymatteryield
3.2.3.4 Crude protein Percentage
3.2.4 Discussion
3.3 Experiment 3: The effects of different sowing ratios on
herbage yield and protein content of oat, vetch and
medic
3.3.1 Introduction
3.3.2 Materials and methods
3.3.2.1 Data collection
3.3.3 Results
3.3.3.1 Plant establishment
3.3.3.2 Dry matteryield
3.3.3.3 Crude protein percentage
3.3.4 Discussion
2929
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31
34
34
34
36
37
37
39
4040
40
43
45
45
46
48
53
55
58
58
58
60
61
61
63
68
70
(iv)
3.4
3.4.r3.4.2
3.4.2.1
3.4.3
3.4.3.r3.4.3.2
3.4.3.3
3.4.3.4
3.4.3.5
3.4.3.6
3.4.3.7
3.4.3.8
3.4.4
Experiment 4: The effects of sowing rates and nitrogen
fertilizer on forage production and grain yield' and
quality of mixtures of oats and vetch
Introduction
Materials and methods
Data collection
Results
Plant establishment
Dry matteryield
Number of tillers/m2
Herbage crude protein percentage
Herbage crude protein yield (kg/ha)
Grain yield
Grain weight
Grain crude protein percentage
Discussion
Experiment 5: The effects of nitrogen fertilizer on
forage and grain yield of different oat cultivars and
vetch species as pure and mixed stands
Introduction
Materials and methods
Data collection
Results
Plant establishment and Yield
Plant height
Number of tillers
Grain yield
Grain weight
Soil moisture
Soil mineral nitrogen
Discussion
GENERAL DISCUSSION
APPENDICES
72
91
72
72
74
76
76
78
93
99
103
106
ro7
109
Lt41,r4
tr4116
118
118
131
131
135
r37
r39
r4lr46
r49
155
3.5
3.5. r
3.5.2
3.5.2.r
3.5.3
3.5.3.1
3.5.3.2
3.5.3.3
3.5.3.4
3.5.3.5
3.s.3.6
3.5.3.7
3.5.4
4
5
6 BIBLIOGRAPHY 168
(v)
ABSTRACT
The quantitative and qualitative relationships of cereal and legume species
grown as pure and mixed stands were studied in a series of field experiments
@xperiments 1,2,3,4 and.S) at the Waite Agricultural Research Institute. The effect of
sowing rates, sowing ratios and nitrogen fertilizer, on the plant establishment, dry matter
accumulation, herbage crude protein contents at various stages of growth, number of
tillers/m2 of oats, plant height, soil water status, grain yield, gfain crude protein contents
and the effect of pure cereal and legume or cereaVlegume mixed stands on the residual
soil mineral nitrogen were assessed.
As the sowing rate of oats, medic and vetch increased the early winter forage
production of these species increased during the 1988 growing season. There was
however no significant difference in the dry matter yield between high and medium
sowing rates towffds the end of the season. A similar response in winter forage
production of oats plus vetch sown as pure and mixed stands was recorded in 1989.
The total dry matter yield of oats plus vetch sown at various sowing ratios
increased as vetch seed in the sowing mixture increased from 25 to 75 percent during the
1988. In contrast the total dry matter yield of oats plus vetch grown as mixed crop
increased as the oat content of the sowing mixture increased from 25 to 100 percent in
the sowing mixrure during the 1989 growing season. The dry matter yield of medic
declined 118 days after sowing. The dry matter yield of the mixed oats plus medic
stands was greater than the pure stands of oats or medic 118 days after sowing. The
total dry matter yield obtained from oats plus vetch or oats plus medic was higher from
oats plus vetch mixed stands in the later part of the season compared to that of oats plus
medic mixed stands.
The oar cultivar Dolphin produced significantly higher dry matter yield than
Coolabah oats. Similarly Namoi vetch produced significantly higher dry matter yield
than Popany vetch in the early part of the season. But there was no significant difference
(vÐ
in the dry matter yield within oat cultivÍrs or within vetch species in the later part of the
season. Also there was no significant difference in the gfain yield of oat cultiva¡s. On
the other hand Popany vetch produced significantly higher grain yield than Namoi vetch.
There was no effect of nitrogen fertllizer on the plant establishment when
applied at the time of sowing. The use of nitrogen ferttlizer increased the mean herbage
dry maner yield of oats but it depressed vetch dry matter yield. Also nitrogen fertilizer
increased the dry matter yield of weeds in the early part of the season, however as
maturity approached there was no significant effect of nitrogen on dry matter yield of
weeds. The application of nitrogen fernlizer increased the number of tillers/m2 of oats,
plant height of oats and vetch, also grain yield of oats but it depressed the mean grain
yield of vetch. The effect of nitrogen ferttlizer on the mean crude protein percentage was
significant 48 days after sowing but not at other stages of growth. Application of
nitrogen fertilizer resulted in an increase in the mean grain protein of oats and vetch in
pure stands. However there was no significant effect of nitrogen fertilizer on the grain
crude protein percentage of oats plus vetch in the mixed stands.
The forage protein p€rcentage of vetch was higher than medic which in turn was
higher than the cereals (barley, oats and triticale). The protein percentage of oats and
vetch decreased with the progressive stages of maturity. The protein percentage of vetch
was significantly higher than oats throughout the growing season with one exception that
48 days after sowing the protein percentage of oats was significantly higher than vetch.
In the later part of the season the herbage crude protein percentage of oats significantly
increased in the mixed stand of oats plus vetch compared to the pure stands of oats. On
the other hand the herbage crude protein percentage of vetch decreased in the mixed
stands of oats plus vetch compared to the pure stands of vetch. Similarly, the grain
crude protein percentage of oats was significantly higher in the mixed stands of oats plus
vetch than the pure stands of oats while there was no significant difference in the grain
crude protein percentage of vetch between vetch plots sown as pure stands or mixed with
oats.
(vü)
The soil mineral nitrogen concentration was higher on 128 and 197 days after
sowing under pure stands of vetch than the pure stands of oats or oats plus verch mixed
stands. Presumably this was a result of the nitrogen fixing capacity of the vetch,
whereas the oats in the pure stands and in mixtures would deplete soil nitrogen
resources.
(vüi)
STATEMENT
This thesis contains no material which has been submitted previously in full or part to
any other University for any degree or diploma and to the best of my knowledge and
betief, it contains no material previously published or written by any other person except
when due reference is made in the text. I consent to the thesis being made available for
photocopying and loan if accepted for the award of the degree.
Sataj Khan
(ix)
ACKNOWLEDGEMENTS
The research for this thesis was planned and ca¡ried out under the supervision
of Mr E.D. Carter, Senior Lecturer in the Department of Plant Science, Waite
Agricultural Research Institute, The University of Adelaide. I am deeply grateful to him
for his patience, guidance, support and criticisms during the planning of experimental
work and the preparation and checking of this thesis.
Special thanks are due to Professor D.R. Marshall and Dr G.K. McDonald for
reviewing drafts of parts of this thesis. I gratefully acknowledge the excellent assistance
of Lynne Giles with statistical analysis and Mr Berry Felberg for all his help with
acquisition of equipment and chemicals. The guidance of Dr F.L Stoddard with
methods of nitrogen analysis and computer assistance is acknowledged with thanks.
I would like to rhank Steve Challis and Diona Mobsby for their help with field
work. Also thanks to Dr. Arun Aryan who kindly provided me with a photograph
(Plate 2.1).
Dr G. McDonald, T. Klein and P. Thongbai rendered invaluable assistance in
the final preparation of the thesis for printing.
I am most grateful for the surgory and medical treatment I received during
hospitalisation in Adelaide during January, 1990.
Finally, I acknowledge the support of the Australian International Development
Assistance Bureau which provided me with a scholarship for this work.
(x)
Figure
2.1
3.1.1
3.2.t
3.2.2
3.2.3
3.2.4
3.3.r
3.4.t
3.4.2
3.4.3
3.4.4
3.5.1
LIST OF FIGURES
Replacement series diagrams illustrating the impact of various
responses to competition on the yields of mixtures and their components.
Plan of experiment 1 and details of treaünents.
Plan of experimen¡.2 and details of treatrnents.
Overall mean plant number of oats, medic and vetch at various stages
of growth sown at different rates.
The impact of sowing fates on plant establishment of oats, medic and
vetch at various stages of growth.
The effects of sowing rates on the mean yield of oats, medic and
vetch at various stages of growth.
Plan of experiment.3 and details of treatments
Plan of the experiment.4 and details of treatments
Density of (a) oats and (b) vetch at various sowing rates and .
sowing mixtures
Crude protein yield of oats plus vetch sown as pure and mixed
stands at various stages of growth.
The effects of sowing fates on the crude protein yield of oats plus
vetch at various stages of growth.
Plan of the experiment.S and details of treatments
Page
t2
33
42
47
47
49
59
73
77
101
101
115
(xi)
LIST OF TABLES
Table
3.1.1 Temperature and rainfall data for the V/aite Agricultural Research Institute.
3.1.2 Mean seed weight , PuritY, germination and number of pure germinating
seeds per kilogram of cereals, vetch and medic cultivars used in the field
experiments at the Waite Institute.
3.1 .3 Expected and actual plant esøblishment of barley, oats, triticale and vetch
cultivars when sown as forage crops.
3.1 .4 Density, yield, crude protein content and crude protein yield of different
cultivars of barley, oats, triticale and vetch.
Page
32
3.2.r
3.2.2
3.2.3
3.2.4
3.2.5
3.2.7
3.2.8
3.2.9
3.2.6 Overall yield of sown species (oats, medic and vetch) at two stages of growth
when these species were sown at different rates.
Summary of ANOVA, density and total yield of oats, medic and vetch sown
at various sowing rates.
The effects of sowing fates on density (plants/m2) of oats, medic and vetch
132 days after sowing.
The average effects over all sowing fates on yield of oats, medic and
vetch at various stages of growth.
The effects of sowing fates on total yield (kgDlvl/ha) of oats, medic and
vetch 101 days after sowing.
Summary of ANOVA for yield of sown species and weeds in plots of oats,
medic and vetch sown at different rates.
The effects of sowing rates on the overall yield of sown species
(oats, medic and vetch) at two stages of growth.
Mean yield of weeds in oats, vetch and medic plots at two stages of growth
when these species were sown at different rates.
The effects of sowing rates (mean of oats, medic and vetch) on the dry
matter yield of weeds at two stages of growth.
34
36
38
45
50
50
51
51
52
53
54
54
3.2.r0
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.3.6
3.3.7
3.3.8
3.3.9
3.3.10
3.4.1
3.4.2
3.4.3
3.4.4
(xü)
The effects of different sowing rates on the crude protein percentage of oats,
medic and vetch 132 days after sowing. 55
Density of oats and vetch som as pure and mixed stands when the data was
statistically analysed for oats vs vetch species differences ' 62
Mean plant density of oats:vetch and oats:medic sown as pwe and mixed stands
when combined data of oats plus vetch and oats plus medic was statistically
analysed for differences at various sowing ratios. 62
Density of oats and medic sown as pure and mixed stands when the data was
statistically analysed for oats vs medic species differences. 63
Yield of oats plus vetch sown as pure and mixed stands. &
Yield of oats and vetch at various stages of growth when sown at different
ratios in the mixture. 65
Yield of oats plus medic sown as pure and mixed stands. 66
Yield of oats and medic at various stages of growth when sown at different
ratios in the sowing mixture. 67
Comparison of the total yield of oats plus vetch and oats plus medic
combinations sorwn as pure and mixed stands. 68
Crude protein percentage of oats and vetch sown at different ratios. 69
Crude protein percentage of oats and medic sown at different ratios. 69
Summary of ANOVA of plant density, yield of oats and vetch sown at
various sowing rates, sowing ratios and nitrogen treatnents' 80
Summary of ANOVA of plant density and yield of oats and vetch sown at
various sowing rates, sowing ratios and nitrogen treaünents. 79
The effects of different sowing rates and sowing ratios on the number of
plants/m2 of oats plus vetch. 81
The effects of sowing rates and sowing ratios on yield of oats and vetch sown
as pure and mixed stands 48 days after sowing. 82
3.4.5
3.4.6
3.4.7
3.4.8
3.4.9
3.4.r0
3.4.1r
(xüi)
The effects of sowing rates and sowing ratios on yield of oats and vetch sown
as pure and mixed stands 76 days after sowing.
The effects of sowing rates and sowing ratios on yield of oats and vetch sown
as pure and mixed stands 159 days after sowing.
The effects of nitrogen on the mean yield of oats and vetch sown as pure and
mixed stands at various sowing rates.
The effects of nitrogen fertilizer on yield of oats and vetch sown as pure and
mixed stands at various sowing rates 131 days after sowing.
The effects of nitrogen fenilizer on yield (kgDlvl/ha) of oats and vetch sown
as pure and mixed stands 104 days after sowing.
The effects of nitrogen fertilizer on yield (kgDMlha) of oats and vetch sown as
pure and mixed stands 131 days after sowing.
Summary of ANOVA on yield of weeds at various stages of growth and also
tillers/m2 of oats.
3.4.12 Mean yield of weeds at various stages of growth from plots of oats and verch
sown as pure and mixed stands.
3.4.13 Yield of weeds at different stages of growth from plots of oats and vetch
sown at various rates in pure and mixed stands.
3.4.14 The effects of nitrogen fertilizer on yield of weeds (kgDlvl/ha) at various stages
of growth from plots of oats and vetch sov/n as pure and mixed stands.
3.4.15 The effects of different sowing rates on tiller nuinber in oats gfown with vetch
as pure and mixed stands.
3.4.16 The effects of nitrogen fertilizer on tiller number in oats sown with vetch in
pure and mixed stands.
3.4.17 Summary of ANOVA of oats and vetch crude protein percentages at
various stages of maturitY.
3.4.18 Mean crude protein percentage of oats and vetch sown as pure and mixed stands
at various stages of growth.
(xiv)
3.4.19 crude protein percentages of oats and vetch sown as pure and mixed stands
131 days after sowing.
3.4.20 Crude protein percentages of oats and vetch sown as pure and mixed stands
185 days after sowing.
3.4.2L The effects of different sowing rates on mean crude protein percentage of
oats and vetch at various stages of growth.
3.4.22 The effects of nitrogen fertilizer on the mean crude protein percentage of
oats and vetch at va¡ious stages of harvest.
3.4.23 The effects of sowing rates and nitrogen ferttlizer on crude protein percentages
of oats and vetch sown as pure and in mixed stand 185 days after sowing.
95
96
97
97
98
99
r02
t02
103
104
105
106
r07
108
3.4.24
3.4.25
3.4.26
3.4.27
3.4.28
Summary of ANOVA for crude protein yield of oats and vetch when sown as
pure and mixed stands.
The effects of different sowing ratios and sowing fates on crude protein yield
from oats and vetch 76 days after sowing.
The effects of nitrogen fernhzer on total crude protein yield of oats and vetch
at various stages of growth.
The effects of different sowing ratios and nitrogen fertilizer on crude protein
yield (kg,/ha) of oats and vetch 131 days after sowing'
Summary of ANOVA of grain yield and grain crude protein percentage of
oats and vetch.
3.4.29 The effects of different sowing ratios and sowing rates on grain yield of oats
and vetch.
3.4.30 The effecrs of nitrogen fertilizer on grain yield (kg/ha) of oats and vetch
sown at various sowing ratios.
3.4.31 Mean grain weight of oats and vetch sown as pure and mixed stands
at various sowing rates.
3.4.32 Grain crude protein percentage of oats and vetch sown as pure and
mixed stands.
(xv)
3.4.33 The effects of nitrogen fertilizer on percent grain protein of oats and vetch.
3.5 . 1 Summary of ANOVA on plant establishmnet and yield of different oat
cultivars and vetch species when plant establishment and yield
was statistically analysed for cultivars and species differences.
3.5.2 Summary of ANOVA on plant establishment and yield of different oat
cultivars and vetch species when data for establishment and total yield
of oats and verch was statistically analysed.
3.5.3 Density lplants/m2) of oat cultivars and vetch species sown as pure and
mixed stands.
3.5 .4 Density of oat cultivars and vetch species at various sowing ratios sown
with and without nitrogen fertilizer.
3.5.5 Total yield (kgDM/ha) of oats cultivars and vetch species sown as pure
and mixed stands with and without nitrogen fertilizer at various
stages of growth.
3.5.6 Total yield of oats cultiva¡s and vetch species sown as pure stands and
mixed stands with and without nitrogen fertilizer at various stages of growth.
3.5,7 Yield 55 days after sowing of oat cultivars and vetch species sown as pure
stands and mixed stands .
3.5.8 Yield, 83 days after sowing of oat cultivars and vetch species sown as pure
stands and mixed stands .
3.5.9 Yield, 145 days after sowing of oat cultivars and vetch species sown as
pure stands and mixed stands .
3.5.10 The effects of nitrogen ferjihzer on the mean yield (kgDlvl/ha) at various
stages of growth of oat cultivars and vetch species sown as pure
and mixed stand.
3.5.1 1 The effects of nitrogen fertilizer on the yield 83 days after sowing of oat
cultivars and vetch sPecies .
3.5.12 The effects of nitrogen fertilizer on the yield (kgDlvf/ha) of oat cultivars and
vetch species 118 days after sowing.
109
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119
t20
t2l
122
r23
r25
t26
t27
tzt
t24
128
(xvi)
3.5.13 The effects of nitrogen fertilizer on the yield (kgplvl/ha) of oat cultivars and
vetch species 145 days after sowing.
3 .5.14 Summary of ANOVA of weeds yield from plots of oat cultivars and verch
species sown as pure and mixed stands.
3.5.15 Mean weeds yield at various stages of growth from plots of oat cultivars
and vetch species when sown as pure and mixed stands.
3.5.16 Summary of ANOVA of plant height, number of tillers, grain yield and
grain weight of different oats cultivars and vetch species.
3.5.17 Plant height of oats and vetch sown as pure stands and mixtures.
3.5.18 The effects of nitrogen fertilizer on plant height of oats and vetch.
3.5.19 Theeffectsof nitrogen fertilizeronthemeantillersnumberof oatcultivars
sown as pure and mixed stands with vetch species with and without nitrogen
fertilizer.
3.5.20 The effects of different sowing ratios on the total mean grain yield (oat + vetch)
of nvo oat cultivars and vetch species with and without nitrogen fer1l,hzer.
3.5.2I Mean grain yield of different oat cultivars and vetch species sown as
pure stands and mixed stands.
3.5.22 Mean grain weight of different oat cultivars and vetch species sown as
pure and mixed stands.
3.5.23 Summary of ANOVA of soil moisture percentage in oats, vetch pure and
mixed plots at late stages of maturity.
3.5 .24 The effects of different oat cultivars and verch species sown as pure stands and
mixed stands on the mean soil moisture percentage at late stages of maturity.
3.5 .25 The mean soil moisture content at two depths at late stages of maturity
3.5.26. Summary of ANOVA of soil total mineral nitrogen (ppm) in oats, vetch pure
stands and mixtures.
3.5.27 The effects of oats and vetch in pure stands and mixed stands at va¡ious stages
of growth on soil total mineral nitrogen (ppm) .
r29
130
130
t32
133
t34
135
136
137
138
140
r40
r4l
142
r42
,l
(xviÐ
3.5.28 Soit total mineral nitrogen (ppm) at at va¡ious stages of growth and at two
depths in plots of oats and vetch sown as pure stands and mixtures.
3.5 29 The effects of oats and vetch in pure stands and mixed stands on soil total
mineral nitrogen (ppm) at two depths 70 days after sowing.
3.5.30 The effects of oats and verch in pure stands and mixed stands on total
mineral nitrogen (ppm) at two depths 128 days after sowing.
The effects of oats and vetch in pure stands and mixed stands on soil toal
mineral nitrogen (ppm) at two depths 197 days after sowing.
LM
r43
r45
r453.5.31
'jl,
I
üq{t
Plate
2.1
3.5.1
(xvüi)
LIST OF PLATES
Schematic representation of a legume/cereal mixture
Illustration of the heights of the two oat cutivats, Coolabah (lefÐ and
Dolphin (righÐ at stem elongation (above) and panicle emergence (below).
Page
t4
145a,
I
¡
i
I
It,
T'I
I
ì
I
(xix)
LIST OF APPENDICES
Appendix
Table 5.1 Experiment2.Meandensity at different at different stages of growth of
oats, medic and veæh at various sowing rates
Table 5.2 Experiment2.Theeffects of sowing rates on mean density of
(oats + medic + vetch) at various stages of growth.
Table 5.3 Experiment2.The effects of sowing fates on total mean yield of
(oats + medic + vetch) at various stages of growth.
Table 5.4 Experiment 3. Total mean yield of oats andverch at various stages of
growth when sown as pure and mixed stands.
Table 5.5 Experiment 3. Total mean yield of oats and medic at various stages of
growth when sown as pure and mixed stands.
Table 5.6 Experiment 4. The effects of sowing rates and sowing ratios
on numbers of plants/m2 of oats and vetch.
Table 5.7 Experiment 4. Mean yield at va¡ious stages of growth of oats and
vetch sown as pure stands and in mixtures.
Table 5.9 Experiment 4. The effects of nitrogen fertilizer on mean yield at various
Stages of growth of oats and vetch sown as pure stands and mixtures.
Table 5.10 Experiment 4. The effects of different ratios on crude protein yield of oats
and vetch at various stages of growth.
Table 5.11 Experim ent 4. The effects of different sowing rates on total crude
protein yield of oats and vetch at various stages of growth'
Page
155
155
156
157
r57
158
159
r59
156
.I
lf'ii,I
Table 5.8 Experiment 4. The effects of different sowing rates on mean yields at
various stages of growth of oats plus vetch grown as pure stands and mixtures. 158
II
;
3
160
I
(xx)
Figure 5.1 Experiment 3. Dry matter yield of oats and vetch sown as pure
and mixed stands 33 days after sowing.
Figure 5.2 Experiment 3. Dry matter yield of oats and vetch sown as pure
and mixed stands 62 days after sowing.
Figure 5.3 Experiment 3. Dry matter yield of oaS and vetch sown as pure
and mixed stands 90 days after sowing.
Figure 5.4 Experiment 3. Dry matter yield of oats and vetch sown as pure
and mixed stands 118 days after sowing.
Figure 5.5 Experiment 3. Dry matter yield of oats and vetch sown as pure
and mixed stands 147 days after sowing.
Figure 5.6 Experiment 3. Dry matter yield of oats and medic sown as pure
and mixed stands 33 days after sowing.
Figure 5.7 Experiment 3. Dry matter yield of oats and medic sown as pure
and mixed stands 62 days after sowing.
Figure 5.8 Experiment 3. Dry matter yield of oats and medic sown as pure
and mixed stands 90 days after sowing.
Figure 5.9 Experiment 3. Dry matter yield of oats and medic sown as pure
and mixed stands 118 days after sowing.
Figure 5.10 Experiment 3. Dry matter yield of oats and medic sown as pure
and mixed stands 147 days after sowing.
Figure 5.11 Soil total mineral nitogen (ppm) concentation at various stages of
maturity in plots of oats plus vetch sown as pure and mixed stands.
Figure 5.12 Soil total mineral nitrogen (ppm) at various stages of maturity
at two depths in plots of oats plus vetch sown as pure and mixed stands.
161
161
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162
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t64
165
165
166
167
167
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l
Sfát¡-TH INSì){ü.ffi..1 . al"q.2/Ii$fi.,r ¡t,r
1. GENERAL INTRODUCTION
Livestock production'over much of southern and eastern Australia is based on
pastures where soil nitrogen status is maintained or improved by the use of self-
fegenerating annual medics (Medicago spp.) or subterranean clovers (Trifolíum
subterranean) pastures. Generally the medic pastures, and frequently the subterranean
clover pastures, are grown in a rotation with cereals (Carter 1974; 1975; Carter 1982:
Puckridge and French 1983; Carter 1987).
In the more temperate ateas of Australia, low temperatures in winter may reduce
pasture growth rate and lead to feed shortages (McFarlane 1965) and reduced year-round
stocking rates. This problem has been the focus and the main interest of many
investigators in Australia (e.g. Brown lg75) and in other pafts of the world (e.g' rffheeler
1981). Generally stock feed containing from 13 to 207o crude protein is required to
maintain livestock gain and supplements of hay or grain are often necessary (McClymont
1956; Beames 1960; Walton 1980). For example winter or late suÍlmer feed supplement
can increase overall productivity of a property and reduce or eliminate lambing difficulties
and losses (Sergeant 1956; Willoughby 1959; Beames 1960)'
In southern Australia fodder conservation is widely practised (Underwood and
Millington 1944; Radcliffe and Newbery 1963) but the conservation of surplus pasture as
hay or silage and its subsequent feeding to animals is expensive and has fundamental
disadvantages when considered in the context of practical year-long systems of animal
production. In particular, where there is a low stocking rate there will be potential for
conserving surplus herbage but there is little nutritional need, while the converse holds
with high stocking rates. Further the redistribution of feed supply involved in the use of
hay or forage may affect the animal's own conservation mechanism, which is based on the
storage of body reserves (Hutchinson 1971).
An alternative to feed supplements is to use a complementary forage crop during
periods of pasture shortages. A forage crop was defined by Dann (1972) and Carter
2
(Lg74, l97S) as an annual which is sown to provide green feed for livestock and
supplement the normal pastures in those times of the year during which pasture
productivity is limiting. These crops can be broadly divided into two groups; those sown
to provide late summer and autumn feed (e.g. millet, covryeas), and those sown to provide
winter and early spring feed, (e.g. oats, vetch). Three main families of plants are sown as
forage crops; the Poaceae (Gramineae, mainly winter cereals e.g' barley and oats, and
summer cereals e.g. millets, and sorghums); Fabaceae (Papillionaceae, e.g. vetches, and
lupins), and the Brassicaceae (Cruciferae, e.g. turnip, rape and kale).
In the temperate areas of Australia oats are used as an autumn/winter forage crop
or more commonly as a dual-purpose crop (Crofts et al. t970; Lewis 1988). The use of
oats as dual-purpose crop may enhanced the economic stability of the farm enterprise by
contributing to meat or wool production in addition to grain production. In mixed farming
enterprises oats also assist in weed control and reduce the incidence of fungal diseases
such as "take-all" in wheat and, barley by reducing alternative hosts for pathogens (Brown
197s).
Annual Medicago species are also reported to be productive in winter and have the
advantage of greater growth rate than other temperate legumes (Bowdler and Lowe 1980).
An alternarive to Medícago species are peas (Pisum sativum) and vetches (Vícia spp.).
Vetches ¿ìre more productive than peas (Bailey 1952), and have better chemical
composition for sheep (Snook 1947; Johanson 1948; Farrington 1974)' Furthermore
vetches are hardier and are less susceptible to insects pests particularly the pea weevil
(Bailey Lg52). Also vetch gave an early light granngand carry ¡vice as many sheep as the
medic pasture does during late winter and spring (Bull and Mayfreld 1990). Vetches grow
well in cool temperatures and provide feed usually containing between 12 and207o ptotein
(Henson and Schotch 1968). Poole (1969) reported four main uses of vetch grown in
western Australia as follows:
(i) Standing dry summer feed: The crop is allowed to mature,left standing and grazed'-
The dry vetch plant is palaøble and also the seeds are large enough and easy to be
3
picked up by sheep. Funhermore the high protein content of the dry vetch material
makes it suitable for "bringing on" late lambs and the weaner "tail" and for
conditioning breeding sheep for mating'
(ii) Grain production: Vetch are grown for grain production for use as seed for
planting. Small quantities are also used in poulUry and stock rations'
(iii) oaten-vetch hay: Because of the highly nutritious quality of vetch, oats-vetch hay
¿ue grown in dairying areas of western Australia'
(iv) Vetch meal: Vetch meal made from vetch hay is becoming popular among stock
firms as alternative to lucerne meal.
Bull and Mayfreld (1990) suggested that the potential use of vetch in Australia still
needed further exploitation and assessment.
Growing forage or grain crops in mixtures has several potential advantages over
pure stands. Trenbath (1974) indicated that the potential advantages included higher
yields, greater stability of yield from season to season, a better spread of production over
the growing period, less susceptibility to diseases or lodging, and an improved quality of
the crop product. Other possible reasons for the adoption of crop mixtures are to maintain
soil fertility by growing legumes with cereals, to spread labour demands, since all the
crops in a mixture do not mature at the same time, and to provide farmers with several
types of food grains. carter (1981) reported some 40 million hecta¡e of crop and sown
pastures in Australia rely on legumes to provide soil nifogen through fixation and hence
reduce the amount of nitrogen fertilizer applied by the Australian crop and livestock
industry by about A$3.2 billion per year.
The use of forage mixtures is not new. It is practised in one form or another in
most countries of the world, from mixed pastures of Europe to mixed crops of Africa'
Asia and Latin America (Ahmad et al. 1979). Mixed cropping is generally associated with
agricultural systems of the developing nations and particularly with subsistence farming
(Baker]lg74),butinterestincerealflegumemixturesisalsodevelopingintemperate
4
regions of Ausrralia and the United States (Searle et at. l98l;Allen and Obura 1983; Chui
and Shibles 1984). The growing of mixtures of cereals and legumes would allow to
improve forage quality and lowêr the use of nitrogen fenilizer (Bowdler and I-owe 1980).
1.1 Aims of the thesis research
There has been considerable research on cereals as forage crops and a lesser
amount of research on legumes (e.g. medic and vetch species) as forage crops. In the case
of cereals the feed quality (protein and digestibility) declines with maturity but legume
species like lucerne, annual medics and vetch in the mixture with cereals have potential to
maintain yields and greatly improve feed quality.
A series of experiments on cereals and legumes were conducted during 1988 and
l9B9 growing seasons. The aim of these experiments was to evaluate the quantity and
quality of these species sown as sole or mixed crops of oats, medic and vetch at various
sowing rates, sowing ratios and nitrogen fertilizer treatments. Furthermore, the research
project aims to improve knowledge and understanding of the ecological significance, of
cereal,/le gume mixtures.
1.2 Site of experiments
The main investigation was by field experiments at Waite Agricultural Research
Institute and Urrbrae Agricultural High School, Adelaide, South Australia. The site is
located at a latitude of 340 58'S, a longitude of 1380 38'E, and an altitude of 1225m-
The climate is of the Mediterranean type with "\ryinter glowing" season lasting 5-7
months and a "summer" drought for the remainder of the year. Winter rains normally
cornmence in the perigd April-May and continue until October-November. A summary of
monthly rainfall means, maximum and minimum daily temperatures from 1925 to 1989 are
given in Table 3.1.1 The soil, an Urrbrae loam, is a red brown earth "with a characteristic
development of horizons with the accumulation of clay and the presence of calcium
carbonate in the illuvial horizons" (Northcote 1981). The red-brown earths were one of
5
the f,çst soils used for growing wheat in Australia and remain one of the most imporønt
cereal growing soils (Williams 1981). The surface soil is poorly structured and subject to
sealing, especially if compacted by stock, machinery, or heavy rains.
6
2. LITERATURE REVIEW
2.L Constraints to forage production in Mediterranean environments
A Mediterr¿nean climate is described as the dry summer-temperate, with mild wet
winters and hot dry summers. The term'Med.iterranean' is used because most of the a¡eas
of this type of climate border the Mediterranean sea or basin. They are generally situated
between 30" and 40o in both the northern and southern latitudes (Leeuwrik 1974) and the
growing season commences following ttre first effective rainfalt in autumn. Plant growth
is restricted to the autuÍtn, winter and spring months. Generally olive and evergfeen oak
are accepted as the indicator plants of the tn¡e Mediterranean environment of the old world
(Rossiter 1966). The so-called Meditenanean region includes areas surrounding the
Mediterranean sea, parts of southern Australia, California, Chile and the southern tip of
Africa (Whyte lg4g). Mean annual rainfall varies from 275 to 900mm within the
Mediterranean region (Buddenhagen 1990). The length of the growing period depends on
the locality and season, but ranges from five to seven months (Presscott and Thomas
lg4g). Soils are generally calcareous and alkaline throughout the Mediterranean regions,
although in coastal areas some soils have no calcium carbonate in the profile and are almost
neutral in pH (I-eeuwrik 1974).
The life cycle of annual pastures in this environment is of interest. In annual
pastures the plants begin from seed each year. Following germination they grow rapidly
during the autumn, more slowly in the winter when temperatures are lower' then very
rapidty in early spring, reaching maturity as the soil dries out, usually in mid to late spring'
The persistence of an annual species depends on its ability to establish rapidly in the
auturnn so that it is potentially in a favourable competitive situation relative to weed species
and to grow in the presence of the grazinganimal for the remainder of the rainfall season
and to set seed in spring before the onset of summer drought' In an unfavourable season
little seed may be set by annual pasture species: which is very important, because of their
dependence on natural reseeding for reproduction and regeneration (Whyte 1949)' High
stocking rates or high seedling mortalities after a false start to the rainfall season are two
7
common causes of reduced seed number and hence pasture of low plant density and poor
winter production (Sharkey et al. 1964)-
More recently, Carter (1987) has reviewed, in detail, the establishment and
regeneration of annual pastures in Australia. The difficulties in the establishment of annual
pasture plants in Mediterranean environments a¡e summarised as:
(1) the uncertain rainfall at the start of the season which is often sufficient for
germination but not enough to maintain further growth, and as a result seedling
mortality occurs;
(2) the hard setting nature of many soils which prevents seedling emergence and
breaks the roots of young plants when the crusts separate from the soil;
(3) the presence of many plants suitable for these regions have various mechanisms
(e.g. dormancy and hard-seededness) which delay germination and spread
germination over many years, thus uniform and rapid germination after seeding is
not possible.
(4) the species, cultiva¡s or mixtures should not only survive to maturity but also set
adequate seed for fegeneration in the following growing season.
The above features result in great variation in the botanical composition of annual
pastures not only from site to site but also from year to year (Cook 1942; Heady 196l;
Rossiter 1966; Carter and Lake 1985). For example, Heady (1961) sampled ungrazed
plots under a Mediterranean-type of climate in California from 1953 to 1960 in order to
investigate the yearly fluctuation in the composition of pasture species. Over this period
the range in percentage composition of pasture at the end of the growing season was;
glasses 22 to 87 percent, legumes 1 to 17 percent, Erodiurn botrys 6 to 45 percent and
other broad leaved plants 6 to 32 percent. The magnitude of these differences in the
species composition was associated to the fluctuation in rainfall during the study period.
The high rainfall (1534mm) of 1958 was associated with an extreme grass dominance, but
the lower rainfall (71lmm), and especially the extended dry periods of 1960, led to
8
dominance by Erodiurn sp. In an earlier study Cook (1942) observed at Kybybolyte,
South Ausffalia, that both Erod.iumand capeweed were favoured by dry seasons whereas
clovers dominated in wet ,"urónr. However Trumble and Cornish (1936) reported that
total pasture yield was determined by rain at critical periods rather than total annual rainfall
for a natural pasture at Adelaide, South Australia. At the Waite Agricultural Research
Institute Carter (1968, lg77) and Carter and Lake (1985) have shown that stocking rate
can have a large impact on botanical composition. In their studies low stocking rates led to
grass dominance, medium stocking rates to capeweed dominance and high stocking rates
to legume dominance.
In contrast to annual pasture species perennial plants, such as lucerne do not
depend on seed set or seedling glowth to maintain the stand from year to yeÍr' The
number of perennial plants changes little from one year to the next, provided there is no
waterlogging or severe overgrazing (Walker 1958). Carter (1958) has reported better
growth of perennial grasses, where rainfall is high and the growing season is long. The
survival of these species depends on their foot systems, which penetrate deeply into
subsoil moisture, and their leaf structure, which reduces transpiration rates. These factors
enables the plant to live through long periods of drought and high evaporation (Whyte
1949; Buddenhagen 1990).
Seasonal variation governs the farming systems in Mediterranean-type
environments. Annual crop rotation is practised in areas with a rainfall between 450 to
700mm . This fotation may include wheat, barley and peas as grain crops and vetches'
clovers, medics and lucerne as forage crops. However in the 300 to 450mm rainfall zone
of the Mediterranean basin fallowing is common in order to conserve moisture and
accumulate nitrogen. Crops such as wheat, barley, oats, annual medics and lentils are
grown (Leeuwrik 1974).
Droushiotis (1985) and Buddenhagen (1990) suggested that an ipcreased effort
should be made to maximise the growth of forage species during the rainfall season in
Mediterr¿nean climatic zones to increase total biomass accumulation, even at the expense
9
of reduced seed yield and usable protein. It is theoretically possible, but practically
difficult, to overcome some of the difficulties of forage production in Mediterranean
environment. These include thê system of land tenure, the paucity of suitable pasture and
forage crop species or adapted and improved cultivars of these species. Furthermore, the
provision of animal feed is not only dependent on the presence or absence of irrigation
water or rainfall, but is also directly related to erosion of the lands covered now or
formerly with natural vegetation and to the low productivity of the a¡able land (Whyte
Lg4g). Water availability for inigation is severely limited in southern Australia, while soil
erosion and salinization represent a constant threat to soils. Moreover pasture
establishment problems in Australia are associated with soil acidity, difficiency of trace
elements (Tiver 1960) and the toxic effects of nitrogenous fertilizer banded with the seed
(Carter 1967).
2.2 Background to mixed croPPing
Mixed cropping is the growing of two or more crop species simultaneously in the
same field during a growing season (Willey 1979). Mixed cropping has the potential to
increase dry matter production at the times when pasture production is low. Often the
productivity of a mixture is greater than that of some or all of its components grown in
pure stand (Trenbath 1974; Rao and V/iltey 1980; Dahmane and Graham 1981; Osman and
Osman 1982; Osman and Nersoyan 1986). Four main types of mixed cropping, based on
the degree of mixing of the component species, have been identified by Andrews and
Kassam (1976), as follows:
(l) Intercropping: growing component crops simultaneously with no distinct row
arrangement and including mixing within the row.
(2) Row íntercropping: growing component crops simultaneously but in different rows.
(3) Strip intercroppíng: growing component crops simultaneously in different strips to
permit the independent cultivation of each crop.
10
(4) Relay intercropplng: growing component crops in relay so that growing periods
only briefly overlap.
Trenbath (Ig74) highlighted three approaches to research on mixtures. The f,rst
was to identify high yielding combinations by screening mixtures composed of more or
less randomly-selected genotypes for possible high yielding combinations. The second
objective was to test the reported advantages of traditionally-grown mixtures. The third
objective was to gain an understanding of the processes which lead to mixture advantages
so that in a specific environment it would be possible to make a rational choice of
components to produce mixtures showing benefits unobtainable from pure cultures. The
latter two approaches appear to be a more rational approach to developing an appropriate
combination of species.
The most useful crop combination for mixed cropping varies with geographical
location: there may be an intercropping of tree crops, intercropping of tree and freld crops'
or intercropping of field crops (Ofori and Stern 1937). In intercropping, combinations
may vary on the basis of morphology and growth duration. cereals and legumes of
varying maturity are commonly used in intercropping systems (Ofori and Stern 1987). In
tropical and subtropical regions, the cereal component is usually maize, sorghum, millet
or, to a lesser extent, rice and the legume is usually cowpea' groundnut, soybean,
chickpea, bean or pigeonpea (Baker 1979). In some temperate regions intercrop systems
consist of wheat, oats, or barley as the cereal component and field bean, vetch, lupin or
peas as the legume component (Ofori and Stern 1987).
2.3 Competition and yield response
The success or failure of a particular mixture to improve dry matter production
depends on the ability of the mixture to explore the environment more fully than the pure
stands of the component parts. Therefore, competition between species in the mixture
greatly affects the nature ofthe crop.
11
Most recent studies have examined pairwise competition between species g¡own
in replacement series. This experimental design was introduced by de Wit (1960) and
includes a series of treatments, which consists of pure stands of each species and some
mixture treatments, formed by replacing given proportions of one species with an
equivalent proportion of the other. The simplest replacement series consists of two pure
stands and a single mixture treatment, usually containing 50Vo ofeach species. Results of
experiments based on the replacement series can, in theory, take any of the following four
basic forms (Harper 1977); (1) Equivalent demands on the environment (2) Compensation
(3) Mutual inhibition (4) Mutual cooperation. Each of these is considered in greater
detail below.
(l) Equivalent demands on the envirownenf: where the yield of nvo species in mixtures
results in each contributing to the total yield in direct ratio to their proportion of
sown seed. Harper (1977) suggested that this may be due either, at a density which
may be so low that individuals within it do not interfere with each other or, at higher
densities where each species interferes equally with each other. For example the
effect of one species, say, "I", on another species "J" is precisely the same as that of
J on J and the effect of J on I is the same as of I on I (Figure 2.la).
(2) Compensa.tionis a common situation, where one species yields less than expected
and the other more. In this case the competitive abilities of the two species are
obviously different. The effect of species "I" on species "J" is greater than of "J"
On "J" and the inflUenCe Of "J" On "I" iS leSS than Of "I" On "I" (Fig. 2'lb,C)' The
two species make demands on the same environmental resources' but there is a
differential between them. Harper (1977) suggested that a species may be more
productive in pure stand than in mixtures where compensatory effects are involved'
(3) Mutual Inhibition is rare in practice but has been reported by some workers (e'g'
Ahlgren and Aamodt 1939: Donald 1946; Harper 1961). In this case, the actual
yield of each species is less than expected. The effect of species "I" on species "J"
(Fig. 2.ld) is greater than that of "J" on "J" and the effect of "J" on "I" is greater
t2
than that of ,,I,' on "I". Such a situation would arise if each species damaged the
environment of the other more than it damaged its own environment (Harper 1977)-
(4) Mutual cooperation is a relatively common practice and the yield of each species is
gteater than expected. In this case the effect of species "I" on species "J" is less
than that Of "J" On "J", and the effeCt Of "J" On "I" iS leSS than that Of "I" On "I"
(Fig. 2.1e). Harper (1977) described the situation as one in which each species
escapes some measure of competition with each other. He further explained that the
gowth of "I" may be limited by resource (a) and that of "J" by resource (b) or the
growth of "I" occurred in a different season to "J" so that neither species interfered
with each other for gïowth demands. This type of competitive response invariably
is the best in terms of maximising forage yield of crops. The other three responses
lead to equal or reduced yields of mixtures.
Moóei I Mode¡ IIo
1 4J
0-----à xI
(b)
Model IlÞ
aJ +J1
!g
OxJx1 0
<--
(c)
XJo
<- CxÌxJ
0(c)
Model III
I+J
Model E
!
xJ0
0XI
xJC
<-
(e)
c<--
---------+{d)
Figure 2.1 Replacement series diagrams illustrating the impact of various
responses to competitor or the yietds of mixtures and their components
(From Harper l9l1)
t3
2.4 Biological basis for mixed cropping advantages
Higher yields have bien obtained from mixtures, compared to an equal area
divided between monocultures of the component species in the same proportion as they
occur in the mixture in a range of species combinations (Trenba¡h 1974; Rao and Willey
1980; Dahmane and Graham 1981; Osman and osman 1982; Osman and Nersoyan 1986).
As noted above under (4), a yield advantage usually occufs because component crops
differ in their use of growth resources in such a way that when they are grown in
combination they are able to complement each other and so make better overall use of
resources than when grown separately (V/illey 1979). In other words the component
crops are not competing for the same overall resources. For example, plant species with
different root systems can exploit different layers of the soil (Trenbath 1974). A case in
point was reported by Ellern et aI. (1970) who showed that Avena fatua and Avena
strigosa have different root system distributions in the soil. These differences were
maintained in mixed ,tund, of the two species.
As emphasised by Willey (1g79),to achieve maximum advantage from mixed cropping the
degree of complemeniurity between the components must be maximised and intercrop
competition must be minimised. He further suggested that growing component crops with
different morpho-physiological characteristics may complement each other, rather than
compete for, the Same resources at the same time, and is one way of achieving benefit
from mixed cropping. In mixed cropping the stands might be improved because all the
species in the mixture Íìre not affected by the same hazards (Chapman and Carter 1976)'
Trenbath, (lg7 4)reported that in a mixture of two grass species, (the names of the species
were not mentioned), which differed markedly in time of development, plants of both
components had more tillers than the plants in corresponding monocultures.
Unfortunately he did not report the total biomass which is the matter of major interest. In
gfass-legume mixed cropping the grass component depletes soil nitrogen and legumes f,rx
more nitrogen (Plate 2.1; Postgate 1982; Morris et al.1986). Grass grown in pastures
mixed with legumes utilize some of their nitrogen requirements from nitrogen released by
14
CEFEALNITROGEN ASSIMILATION
MA¡NLY IN LEAVES
t.o.
N. FERTILIZ E RS
sOLÅR INERGY
/
!\
ç
,'
//lr
LEGU!.¡E
NITFOGEN FIXATION
IN ROOT NODULES
co¿
À 1M0sP,{ÉRtO-N
NITRATE1
IXEI].N
PHOTOSYNTHATES./ 0Ð
t\.
ttt¡¡
d le
I
Plate 2.1 Schematic gume/cereal mixture.
15
the legume (Goodman and Collison 1986), particularly when they afe grown together for a
long period. Agronomic factors such as the proponion of crops in the mixture' fertilizer
application, and relative time of sowing can regulate competition between crops for factors
limiting growth (Harper 1961; Davidson ¿r al' 1990)'
Willey (L97g) suggested the possibility of spatial complementarity; a combined
leaf canopy which may make better spatial use of light, or a combined root system may
make better spatial use of nutrients and or water. Unlike water and nutrients, light is a
resource that cannot be stored for later use, it is 'instantaneously available' and has to be
,instantaneously intercepted' if it is to be used for photosynthesis @onald 1961)' If it is
not intercepted by chloroplasts in the leaves or other green parts of plants it is effectively
lost. In situations where water and nutrients are not limiting factors, the rate of dry matter
production by a crop is primarily determined by the amount of light intercepted by its
foliage (Monteith lg72). Many workers (e.g. Baker and Yusuf L976; Lakhani 1976:
willey and Roberts 1976; all cited by witley lg7g)considered that light was probably the
most important factor when better temporal use of resources was achieved'
Hall (1974) has shown that soil nutrient uptake was greater by mixtures than
monocultures. However, while it has often been claimed as the underlying cause of the
yield advantages of mixtures, it is usually impossible to determine whether this is true' or
alternatively, the greater uptake of nutrients is the result of greater yields' In particular' it
is possible for specific mixtures, that the nutrient demands of component crops at different
stages of growth may result in greater soil nutrient uptake even though these components
have a simila¡ growing Perid.
Mechanical factors may also lead to improved yield by a mixture' For example' if
one componenr crop with potentially higher yield in monoculture is suscepúble to lodging
and the other component crop resists lodging strongly enough to cause the mixture to
stand, the mixture may be higher yielding than either of the pure components sown alone
(Trenbath lg74). Legumes such as vetches and peas in mixtures with cereals may remain
in an erect position and thus facilitate mechanical harvesting.
16
Marshall and Brown (1973) have shown in a theoretical study of mixture stability
that varietal mixtures are mosf likely to show agronomically useful stability in highly
variable environments to which the available genotypes were not individually well adapted'
Hence, because crop production is often markedly influenced by each of a number of
climatic, edaphic and agronomic factors, different component species of mixtures which
radically differ in their range of adaptation should ensure that there will be something to
harvest even in the worst season (frenbath 1974)'
2.5 Use of cereals and legumes for forage production in
pure stands and mixtures
Annual forage crops have a potential role in providing feed for animals at times of
the year when either both quality or quantity of available pasture is deficient. At such
times some types of animals, for example, ewes in pregnancy or weaner sheep can be
vulnerable to pasture def,rciency (Dann l97l). Annual forages may improve one or more
of the following characteristics of a pasture total dry matter production and distribution,
acceptability and quality of forage, the resistance of plants to drought and recovery after
grazing, ease of establishment and response to fertilizer. Forage crops have a special role
in the early stages of property development (when little improved pasture is available), in
the preparation of land for the sowing of permanent pasture, and as companion crops for
pasture establishment. However the value of fodder crops in many farming systems
remains a conffoversial issue (Dann 1971). Any one of the cufrently used winter crops
rarely overcome all dehciencies in pasture production and this probably explains why the
number of crops used is large and genetically diverse'
Data in the literature suggests that cereals can produce high dry matter yields'
Watson et al. (1958) recorded barley dry matter yields of 6,000 kgÍta at ear emergence and
lz, mkg/ha 6 weeks later. The maximum dry matter yield of barley in an experiment by
Kirby (1g67)was 10,000 kg/ha. Oats produced maximum dry matter yield of 8,000 kg/ha
{
I!fÌI
t7
,I
in upland conditions in Scotland (Nicholson lg57) with a digestibility of dry matter of
57.5-60.97o during grain filling ('cheesy' stage) declining to a range of 32.9- 6O37o in the
mature crop. Oats is also an important cereal crop in South Australia and is gtown for
grazing,hay and grain production (Mathison 1962; 1964; Bicknetl 1969)' Í(hanet al'
(1989) reported mean dry matter yield of 6J87 kglha of oats without using nitrogen
fertilizer at Adelaide, South Australia when they compared oats/vetch and oats/medic in
various sowing mixtures. Several workers (e.g Wheeler 1963; Crofts 1966a: Archer
lgTI) reported that dry matter yield of oats up to 5,000 k/ha can be obtained during
winter and early spring when the crop is sown into prepared seedbeds. Crofts et al'
(1970) reported average growth of oats 56 ¡o 64kghalday,76 days after sowing' where
the crop was grown on the central coast of New South Wales under non-limiting nutrient
and moisture conditions. Vy'here soil moisture supply is non-limiting, rapid growth of oats
can be expected resulting in the production of a large bulk of early winter forage. Some of
the ateas are sown to oats with dual-purpose potential of the crop' In a good season when
the grazing is plentiful the oat crop may be saved for grain. Crofts (1966b) suggested that
oats sown on a prepared seedbed could make use of light showers of rain which were of
no use to Pasture.
7¡1a¡t et at. (1964)reported that there was not much difference in total forage yield
among top cultivars of rye, oats and wheat but that there was a considerable difference in
the time of year the forage was produced. Rye produced more forage early in the season'
whereas oats and wheat produced most of their forage later in the season' It is very
difficult to find a cultivar of any species which will produce both early gtazing and late
gowth for hay or silage. Davidson et aL (1990) compared early and late maturing
cultivars of wheat in mixtures and concluded that in cool environments grazing of winter
feed crops should be delayed to early jointing stage in order to obtain the gteatest amounts
of winter feed and the highest yields of grain.
V/heeler and Freer (\g73)reported that oats was the most commonly used cereal
and that the winter legumes are used only on a limited scale as forage crops' However'
some workers (e.g Jones and Rees 1912; Scott and Brownlee L976; Bowdler and Lowe
1tì:f
'r
tII
¡
þ
18
1980) reporred that barel medic (Medicago truncatula) cv. Jemalong was compatible with
oats and ryegrass and gave the highest dry matter yield and the best seasonal distribution.
Snail medi c (Medicago scutelláta) produced well in winter and early spring but late spring
production was low compared to other legumes.
In another study, Bowdler and l¡we (1930) compared herbage yield of Jemalong
and snail medic with oats and Wimmera ryegrass grown in grass-legume mixtures or in
nitrogen fertilized gfass monocultures. The Medicago species and oats or Wimmera
ryegrass were sown at 7 and 22kgseed rate/ha rcspectively. Jemalong medic grown with
oats or ryegrass was more productive than the snail medic and oats or snail medic and
ryegrass in mixed stands. In the case of both Jemalong and snail medic, mixtures gave
dry marter yields similar to those of oats or ryegpss fertilized with 205 kgN/ha. Snail
medic gave the best early production reaching maximum growth in late winter, about a
month earlier than Jemalong. Lowe and Bowdler (1988) reported the response of
ryegrass, oats and Jemalong medic to defoliation in mixtures was different to the same
species in the pure stand. The growth of Jemalong medic was influenced by competition
from the companion grass. Dry matter yield of the medic in the early part of the season
was higher when grown with ryegrass than oats, presumably because ryegrass provided
less competition. The probable reason for this may be the prostrate grorwth habit of the
ryegrass cultivar used in this study.
Rihawi et al. (1987) have reported the highest forage yield from an oats plus vetch
mixtures, when vetch and peas were grown in association with barley, oats and triticale.
Ahlgren et at. (1954) observed no increase in DM yield of small grain crops and vetch
mixtures as against small grain alone. Winter barley sown with vetch gave superior yields
to the other small grains sown alone and with vetch in the production of dry matter.
Whittingfon and O'Brien (1968) studied the effects of ryegrass and meadow fescue on DM
yield when grown in mixtures and pure stands. In the earlier stages the mixture did not
yield more than the more productive of the components probably because the proportion of
the higher-yielding component was still relatively small'
1rtf
II
i
t
19
:ìrl]
,l
2.6 Effects of sowing rates on herbage and grain yietds of forage crops
One of the major factors limiting plant growth per unit area is often the density
(Hodgson and Blackman 1956). Sowing fate may generally affect the growth and
development of the crop throughout the gfowing season. Crop growth rate' leaf area' tiller
initiation and tiller death and other par¿rmeters are modif,red by changes in plant density'
Prioul and Silsbury (1932) reported higher crop g¡owth rates of Triþlíum subtercanean
cv. Woogenelup in lower-density swards than in higher-density swards and showed that
this phenomenon was associated with a lower respiratory loss. Davidson (1954) reported
an increased proportion of stem and a decrease in the proportion of roots of subtenanean
clover at high sowing rates. At high densities large seedlings wilt shade or otherwise
compete with small seedlings. on the other hand at low densities, competition may not be
operative in the early stages and hence a greater growth rate will lead to competitive
success @onald 1951).
As plant density increases some plants die. This phenomenon has usually been
reported as changes in plant population (Black 1960) or "self-thinning"' The "self-
thinning rule" (also called -3/2 power rule or Yoda's law) was first proposed by Tadaki
and Shidei (1959), but is best known from the work of Yoda et al' (1963) and its re-
evaluation by white and Harper (1970). The rule relates to plant density (declining over
time) and the mean biomass (increasing over time) of surviving plants in monospecific
populations which are subject to density-dependent mortality.
yoda et al. (1963) observed a general relationship at successive sampling stages
of a stand when self-thinning was operating. They plotted the logarithm of average mass
against the logarithm of density the points formed a straight "self-thinning" line of the
tI
,
r
form:
20
l
logW=r*logN+logK
where \il/ is average single plant weight (g)
N is plant densitY (Plants/m2)
r= -3/2 and K is constant.
The gradient of the lines is in every case nearly equal to -312 or -1'5' irrespective of the
different species. This quantitative relation is so universely found in various plants that it
is termed the 3/2tltpower law of self-thinning'
From an earlier study of Yoda et al. (1957) it can be confirmed that the process of
self-thinning is density-dependent. High sowing rates increased the variance of growth
rate of individual plants, accelerated competitive interaction between adjacent standing
plants and led to high mortality. Furthermore, overcrowded plant stands could not reach
maturity and as a result seed production was affected, unless the initial plant density was
significantly lowered by the self-thinning process' They further suggested that the pure
stand of a certain plant species reached a population plateau, the density of which was
dependant on time or stage of development of individual species.
In cereals, as in many crops, increasing plant density leads to an increase in total
dry matter until a yield plateau is reached, after which increasing density gives no further
increases in yield (Donald 1951; Holliday 1953, 1960; Aspinall and Milthrope 1959; Dann
lgTI). The data upon which this statement is based often refers to shoot dry weight only'
Grain yield, on the other hand, reaches a maximum with increasing density after which a
further increase in density leads to a fall in grain yield (Holliday 1960; Donald 1963)'
Hodgson and Blackman (1956) working with Vicia faba repotted a reduction in the
number of branches and pods per plant with increased density. Increased plant population
diminished the number of node-bearing inflorescences in the upper part of the shoots'
Briggs (1975) compared three wheat cultivars at three sowing rates (i'e' 33'6' 67 '3 and
100.9 kg/ha). Higher sowing rates resulted in higher grain yield for all cultivars and' a
2l
tendency to earlier maturity. Sowing rates had no effect on plant height, kernel weight or
test weight of any of the wheat cultivars.
An increase in sowing rate of oats from 97 .5 to 2M kglha increased winter dry
matter yields more than four fold near Orange on the Central Tablelands of New South
Vy'ales, but regrowth in late winter and early spring was largely independent of sowing
rates (Crofts 1966a). A sowing rare of 179 kglhawas optimal for producing a large bulk
of forage for early winter grazing. Similar results and conclusions have been reported by
Harris and Roark (1964). In another study under non-limiting nutrient and soil moisture
conditions Crofts et al. (197O) found that a stepwise reduction in row spacings of oats
from 30 to 20 and lOcm generally produced a marked and consistent increase in the
amount of dry matter available 76 days after sowing. The effect was evident in sowings
made in March, April and May, and especially at the high sowing rates of 135 and225
kg/ha. The increased yield associated with narrower row spacings was attributed to an
increase in plant establishment and hence to higher plant population per m2 and
consistently higher leaf area indices, resulting in greater development of individual plants
and more efficient utilization of solar radiation.
The purpose for which crops are to be used (i.e. seed production, gtazing or hay
making) and annual rainfall determine optimum sowing rates. Mixtures of cereal and vetch
are often used for good-quality hay production. Bull and Mayheld (1990) recommended
total sowing rates for mixtures of cereal and vetch at 1 :1 and 1:2 ratios of 4Okg/ha for areas
with rainfall below 400mm, 60kg/ha where rainfall is between 400 to 500mm and 60 to
100 kglha 550mm rainfall areas. They suggested a higher proportion of cereal in the
mixture when used for horses rather than for cattle and sheep. In an earlier study, Arnon
(lg7ì) reporred that 120-130 plants/m2 for pure stands of hairy vetch were appropriate'
Sowing rate forvetch reponed in the literature range fuom4.2 kgÂta (Meakins 1972) to 67
kg/ha(Kamprathetal.|958)and100kg/ha(Dovydaitis1988).
High sowing rates of crops can be used as a cultural method to reduce the
comperirive effects of weeds (Bleasdale 1960). In winter cereals the effects of wild oats
22
(Avena species) and some broad leaf weeds on grain yield are reduced by increasing cfop
density (Ervio Lg72). In a glasshouse experiment increased density of wheat was shown
to reduce the effect of competition on ryegrass from early stages of crop development
(Baret and Campbell 1973).
Crop sowing rates may not only affect herbage yield at a given time but also the
quality. Plant nitrogen content of wimmera ryegrass decreased from l.84%o to l'O3Vo as
density increased from 12.5 to 40,500 plants/m2, 210 days after sowing (Donald 1951)'
He suggested that the decline in nitrogen content at high sowing rates was due to reduced
capacity of the plants to exploit the soil environment due to competition' In contrast'
Holliday (1953) reported an increase in crude protein content with increased sowing rates
of perennial ryegrass, almost reaching maximum values at a sowing rate of 179 kglhain
the f,rrst year.
2.7 Effects of nitrogen fertilizer on herbage and
grain yields of forage crops
Soil fertility is a major determinant of crop and pasture yield' The major soil
nutrients for which plant species most often compete, because their supply is limiting' are
nitrogen, phosphorus and potassium. Among the essential elements for plant glowth'
nitrogen is a major nutrient requirement because most agricultural crops require large
amounts of nitrogen compared to other nutrient elements'
Many forms of nirogen (N) are found in the soil but the greatest bulk is in
organic matter with only a small amount present as inorganic compounds' mainly
ammonium or nitrate ions. These inorganic ions are the usual forms which plants absorb
and from which they synthesise protein. When nitrogen in organic compounds is
converted into inorganic ions it is termed mineralisation' The initial conversion to
ammonium is referred to as ammonification, the oxidation of this compound to nitrite and
23
then to nitrate is termed nitrification (Stevenson 1982). This transfer takes place in the
following stages.
Organic nitrogen + Ammonium -) Nitrite -r Nitrate
The nitrogen content necessary for optimal growth varies between 2 and 57o of
the plant dry weight depending on plant species and stage of development (Marschner
19g9). In nitrogen-deficient soil conditions plant growth is stunted,leaves become yellow
and senescence of older leaves increases as N is remobilised to the growing points'
suboptimal nitrogen supply in cereal crops can reduce tillering because appearance of the
lateral buds is retarded (Hewitt 1963), and root growth is limited (Cook l97l1' Briggs
1978). An adequate supply of nitrogen promotes rapid plant growth, with dark gteen
leaves, other factors being favourable (Stevenson lg82). High rates of nitrogen fertilizer
delay flowering, enhance shoot elongation and inhibit root growth (Klemm 1966 cited by
Marschner 1989) which affects nutrient acquisition and water uptake in later stages'
Furthermore, stem elongation which is enhanced by nitrogen in cereals increases the
susceptibility to lodging and this side effect can become a dominant factor limiting yietd'
Also higher rates of nitrogen can cause "haying off", which is the result of excessive
vegetative growth and consequent shortage of water. This phenomenon frequently causes
reduced grain yield of the crop (Taylor 1965a; 1965b; Kuhn 1980).
Some of the important environmental and agronomic factors that affect the
response of nitrogen are remperature (Blackman 1936; Cook and Lovett 1974; Davidson
and Campbell 1984), moisture (Simpson 1965; Davidson and Campbell 1984)' soil
fertility (Gardner and V/iggans 1960; Dann lgTl), previous crop use (Gramshaw and
Crofts 1969: Brown 1975; Spurway et at. 1976) or soil type differences (Legg and
Stanford 1967).
Cook and Lovett (1974) suggested that the ambient temperatures rather than
nitrogen supply is the limiting factor in growth of oats in winter' Low winter
temperatures, which reduce the rate of fixation of atmospheric nitrogen by legumes
(Gibson 1g63),also reduce the rate of mineralisation of organic nitrogen to available forms
24
(Blackman 1936). He showed that the rate of decomposition of organic matter at soil
temperatures within the range of 6"C tO 8"C was not rapid enough to supply sufflrcient
nitrogen for maximum growth of ryegrass at those temperatures. Crofts (1966a) stated
that on the Central Tablelands of New South Wales there is a period of about four months
in winter when the growth of winter-growing species, Such as oats, ryegrass and pasture
legumes, will respond to the dressing of fertilizers which provide available nitrogen, even
on soils rich in organic matter. However, Archer (1971) and Cook (1971) concluded that
the growth of oats after grazing or cutting in winter was independent of the supply of
nitrogen.
Crofts (1966b) reported that available nitrogen is the limiting factor in d¡y matter
production of forage crops in the Central Tablelands of New South Wales. Soil nitrogen
availability can be increased either by growing a legume in rotation with crops, fallowing
or by applying nitrogen fertilizer. Nitrogen fertilizer increased grain and straw yields of
oats and wheat by increasing the number of fertile tillers on the plant, the number of
spikelets on each head and grain number per spikelet (Single 1964: Halse et al' 1969;
Cook L97l;Langer and Liew lg73). The use of nitrogen fertilizer up to 180 kg/hu did not
increase grain yield of forage crops (Dann lgTl). There was no response to N in the first
and second wheat crop after pasture but in the third successive crop, wheat responded to
nitrogen, the optimum response occurred between 70 and 100 kg N/ha.
In Australia, nitrogen fertilization has increased forage yield of autumn-sown
oats, wirh economic benefits in reducing the winter feed shortage (Crofts 7966a;1966b;
Brown lg75). l-owe et al. (198O) found significant responses of oats to nitrogen fertilizer
both under rainfed and irrigated conditions of extremely fertile soils. In cereal crops the
early application of nitrogen increased the number of tillers, stem elongation and yield
(Needham and Boyd 1976; Kuhn 1980; Grah am et al. 1983; Ga¡cia del Moral et al. 1984)'
25
2.7.I Cereal-legume mixtures
Jepsen (1986) investigâted the possibility of growing peas and barley together as
a grain crop for animal feed. Five different mixtures were sown with ratios of 100:0'
g0:20, 60:40, 40:60, 20:80 and 0:100 barley and peas respectively. The proportion of
peas in the harvested grain was less than the original seed mixtures. In addition the
pefcentage of peas decreased with increased nitrogen fertilizer suggesting that ninogen
fertilizer gave the barley a competitive advantage over the peas.
In another study Moreira (1989a) compared the effects of nitrogen fertilizer and
sowing rate on dry matter yield of pure or mixed stands of oats plus vetch' Forage oats
grown alone showed a high yield response to nitrogen fertihzer. The increased proportion
of vetch had a buffering effect on dry mattef yield. The effect was greatest in nitrogen-
deficient conditions. Dry matter of l2tlha was possible using a high proportion of oats
with good crop nitrogen nutrition, and where vetch made a reduced contribution to total
forage yield and nutritive value as nitrogen levels were increased. similarly, ouknider and
Jacquard (1989) reported greater response to nitrogen by pure stands of oats than oats plus
vetch mixtures. The nitrogen uptake in oats was increased as plant density decreased or
nitrogen rate increased.
Dovydaitis (198S) sowed 200 kg/ha of oats and vetch in25:75,50:50 or 75:25
sowing ratios and applied 0 to 90 kg N/ha. Nitrogen application increased grain yield of
oats but decreased vetch seed yields. Higher yields were attained by the 50:50 seed
mixtures in dry years but an increased proportion of vetch to757o resulted in better yields
in wet years. Kamprath et al. (1958) reported that average dry matter yield of hairy vetch
was slightly depressed from 2,300 to 2,200 kgDMlha by the application of 22 kgN/ha'
Wassermann et al. (1984) reported a positive response of oats plus vetch mixtures to
nitrogen, however, nitrogen depressed the percentage of vetch in the mixture'
Gill and Blacklow (1984) reported early competition for nutrients by weeds in
wheat. Increased growth of annual ryegnss can also reduce the response of wheat to
26
nirrogen (Smith and Levick Ig74). Forcella (19S4) found that after the 3-4 leaf stage
wheat became relatively less competitive for nitrogen than ryegrass.
Despite these results, fesponses to applied nitrogen have not always been as
expected. The response over a na11ow range of nitrogen application is linear (Adeniyi and
Wilson 1960). However, over a fairly wide range the response is generally one of
diminishing returns and there may even be a decline in yield at high levels. Fisher and
caldwell (1g5g) found that for coastal bermuda grass the response to increased nitrogen
decreased gradually. This diminishing response to N is probably a result of increasing
competition for light with the increased production'
2.8 Effect of grass/legume mixtures on protein yield
The intake of digestible nutrients, particularly available energy is the major
nutritional constraint in animal productivity throughout the world (Reid 1982)' For animal
gowrh and lactation, feed quality should exceed the values of 67Vo in digestibility and 13
to l¡Voin crude protein, while with low quality feed,less than65Vo digestibility is suitable
for maintenance only (Raymond 1969; Hughes and Haslemore 1984)' The nitrogen
content of pasture during the late spring and dry summer months varies according to
species and environment (Rossiter 1966). However, mature pastures with a low legume
content ale marginally deficient in nitrogen for the growth of young sheep (Allden 1959)'
several workers (e.g. Meyer et aI. 1957; McDonald and wilson 1980) have
reported a decline in digestibility, crude protein content, carotene, mineral and vitamin
content with plant age, whereas crude hbre and nitrogen-free extracts increased'
However, the yield of both crude protein and digestible dry matter per unit area in crops
tends to increase with advance in maturity until the "milky" grain stage development
(Hughes and Haslemore 1984; Droushiotis and rwilman 1987).
Generally dry matter production, protein and grain yield of cereals respond to
increased nitrogen fertilizer inputs. Mean crude protein contents of barley straw increased
27
from 4.1 to 4.BVo with nitrogen application of 85 kglha (Gately 1916). For seed crops'
generally the higher the nitrogen input the higher the seed protein yield when moisture is
adequate (Hucklesby et at.I97l). Bur crops grown for forage production can accumulate
high levels of free nitrate when given luxury levels of nitrogen fertilizer (Crawfotd et al.
1961). This accumulation of ninate may cause toxicity to farm animals graø,:uirg small-grain
forage crops (Bradley et al. 1940). Nitrate ions are reduced to nitrite within the rumen and
when absorbed this can lead to the toxic condition of methaemoglobinemia in which
ferrous iron is oxidised to ferric, so that the capacity of btood to carry oxygen is reduced
(Raymond 1969). Generally oats, wheat, rye and barley are considered to be nitrate
accumulators (Gul and Kolp 1960). Some workers (e. g. Gul and Kolp 1960; Crawford
et al.l96l:Gordon et al.l962)have reported that nitrate concentration levels decline with
the stage of plant maturity but the nutritive value tends to decrease (Meyer et al.1957).
On the other hand legumes are not only important because of their ability to fix
atmospheric nitrogen by means of Rhizobiun symbiosis but also have a high nitrogen
content, are rich in minerals and highly nutritious @avies et al.1968). Oats plus pea or
vetch mixtures are the most important forages glown on dairy farms in Canada and the
United States (Hodgson and Blackman 1956). Crude protein in oat plants declined from
20 percent to less than 10 percent as the crop matured, while for the same period protein
level in pea plants remained at 15 percent (Brundage and Klebesadel 1970). They
attributed this characteristic of oats and peas to the determinate and indeterminate growth
habits of these species. Oats being determinate in growth habit so the constituent level in
oat herbage during the sampling period changed while pea is indeterminate in growth habit
and the constituent level for the same sampling period remained constant in pea herbage'
A slight decrease in crude protein of oats plus legume (pea, beans, vetch) mixtures at
ripening stage, however, is possible because of a combination of leaf fall and shedding
losses (Henderson and Davies 1955).
Ahlgren et al. (1954) reported highest protein percentages in winter grain sown
alone or with winter vetch during the heading or milk stages, while protein per hectare
from winter grain sown with vetch was highest where harvests were made during the milk
28
or dough stage of development. The most profitable protein production was achieved by
using oats plus pea mixtures with 50 to 65 kilograms of peas and 35 to 50 kilograms of
oats (Hodgson and Blackman 1956).
Similar dry matter digestibilities of wheat, barley, and oats have been reported
when ensiled at rhe same maturity (Cannell and Jobson 1968; Polan et al. 1968)' The
digestibility of these species decreased with increasing maturity.
Jepsen (1936) has shown the effect of nitrogen fertilizer on barley and pea protein
content when grown alone and in mixtures. Crude protein yield increased with increase in
nitrogen rate in barley monocultures and mixtures. In another study Gately (1976) found
higher protein content of barley sown as the first or second crop after pasture in
comparison to when it was Sown as the fourth or later crop. There was a small increase in
protein conrent with each increment in nitrogen fertilization. Anderson (1975) reported
variation in nitrogen concentration within various vetch species where there was
signif,rcantly higher concentrations of plant nitrogen in Vicia sativ¿ than in other vetch
species. He also reported higher concentrations of nitrogen in vetches grown alone than
when grown with oats.
3.1 Experiment 1: The potential productivity of barley' oats'
triticale and vetch cuttivars when sown as forage crops
3.1.1 INTRODUCTION
Annual forage crops, particularly cereals, are used in cool temperate and
Meditenanean environments to increase the supply of green feed during the winter months
(Crofts et a\.1970) and are conserved as hay or silage to supplement pastures during
summer. But the low protein contents of cereals has caused some livestock producers and
dairy farmers to investigate alternative crops as source of protein for feed. Annual legumes,
particularly vetches are productive and have better chemical composition for sheep (Snook
1947;Johanson 1948; Fa:rington lg74). Generally the vetch crop is allowed to mature, left
standing and grazed. The dry residues are palatable and the grain is large enough to be
picked up off the ground by the sheep (Poole 1969). In addition, the practice of utilizing
vetch as a standing crop in summer is economical in comparison to the cost of harvesting
and processing the croP as haY.
A field experiment was designed to study the potential of different cultivars of
barley, oats, triticale and vetch species as forage crops for herbage yield and nutritive value
during 1988 at Waite Agricultural Research Institute farm. The site was sown to barley in
the previous year. For detailed information about the site and soil type see section 1.2,
rainfall data are given in Table 3.1.1.
3.T.2 MATERIALS AND METHODS
Germination Tests: To estimate the proportion of viable seed 100 seeds of all the
species/cultivars included in the experiment were placed on a moist filter paper in petri
dishes in an incubator at 20"C using standard techniques (Myers 1952). The water used for
moistening the filter paper was amended with Thiram@ at the rate of 1'6gÄitre to inhibit
fungal contamination. The number of germinated seeds were counted and removed every
24 hours until germination ceased. Foreign materials (chaff, weed seed' stone and soil)
30
were removed from a subsample of about 4009 of each species and their purity was
estimated. The proportion of viable seeds, sample purity and the mean grain weight were
subsequently used to ensure that the same weight of viable seed was sown' To estimate
mean seed weight 10 subsamples, each of 100 seeds, from each cultiva¡s were weighed and
mean seed weight obtained. In the case of triticale cv. Tiga an extra six subsamples were
weighed and mean seed weight calculated in order to confirm its relatively low mean seed
weight in comparison with cv. Currency.
Design of Experiment: Tlteexperimental design was a randomized complete block
with four replications. The ten treatments comprised two cultivars of barley (Hordeum
vulgare) cvs. Beecher and Forrest, three cultivars of oats (Avena sativa) cvs' coolabah,
N.Z. Cape and (Avena strigosa) cv. Saia, two cultivars of triticale (X Triticosecale) cvs'
Currency and Tiga, one cultivar from each of the vetch species (Vicia sativa) cv'
Languedoc , (Vicia villosa subspecies dasycarpa) cv. Namoi and (Vicia benghnlensis) cv'
Popany. The layout of this experiment is given in Figure 3.1.1' The randomization of the
treatments for all the experiments was performed using the'GENSTAT program'
Seed Inoculation: The seed of vetch species was inoculated with group "E" SU 319
(Rhizobium leguminosarum) of a culture of Rhizobiwn species and the seed of cereals was
pickled with LE-sAN-EL (Fernaminosulf a.i. s0g/kg) to inhibit fungal infections of
seedlings. However barley cv. Beecher was sown without being pickled. A mixture of
superphosphate and lime (approx.226kdha) was drilled at sowing' Urea was broadcast at
the rate of 50kgNlha on the cereal plots 90 days after sowing.
Sowing Details:plots were drilled on 3 June 1988 into a prepared seedbed using a
14-row Connor-Shea drilt with with 15cm row spacings' Plots were l5m long and 2'lm
wide.
31
3.1.2.1 Data Collection
Plant Establishment Counts: To estimate plant density four quadrats each of size 30.0cm x
33.3cm (0.1m2) per plot were cãunted 36 days after sowing.
Harvest Der¿ils: Five harvests were taken through the growing season to estimate
herbage dry matter (DM) yield. Plots were harvested on July 9 (H1), August 7 (H2),
September 4 (H3), October 2 (f14) and October 28 (H5) which were 36, 65,93,121 and
147 days after sowing respectively. At Hl four quadrats per plot each 30'0cm x 33'3cm
were harvested. At H2 four quadrats per plot each 0.25m x 1.00m were harvested. At H3
four quadrats pef plot each 55cm x 60cm were harvested. At H4 and H5 four quadrats per
plot, each 0.5m x 1.0m were harvested.
Dry MatterYield: Plants from each quadrat were harvested with a knife at ground
level and all the samples from each plot were bulked. These samples were dried in a forced-
draught dehydrator at 85oC for approximately 24 hours to determine dry matter (DM)
yields.
Plant Nítrogen: To estimate plant ninogen content, samples were retained at H5.
These samples were dried at 85oC for approximately 24 hours, gtound to pass through a
5mm sieve and then re-ground to pass through a 0.5mm sieve. From these samples a
subsample of 250mg was wrapped in a cigarette paper and put in a labelled container. The
moisture content was measured on approximatety 250mg sample of six sample of each
species. The moisture percentage was calculated from the data and a correction factor for
moisture subsequently used in calculation of nitrogen and protein concentration.
plant nitrogen analyses were made by utilizising the Kjeldahl digestion procedure (Mckenzie
and Wallace 1954) followed by the determination of nitrogen based on a Colorimetric
method using a Technicon Auto-analyser. In this process an emerald colour is formed by
the reaction of ammonia, sodium salicylate, sodium nitroprusside and sodium hypochlorite
(chlorine source) in a buffered alkaline medium at a pH of 12.8. The percentage of protein
was calculated by multiplying the nitrogen percentage by 6.25. Ptotein yield (kg/ha) was
calculated by multiplying percent protein by dry matter yield at the last harvest.
Table 3.1.1. Temperature and Rainfall Data for the Waite Agricultural Research Institute.
(Latitude 3405 8'S Longitude 1 3 8o3 8' Altitude \22 5m)
Temperanre (oC) Mean Rainfall (mm)Months
January
February
March
Aprit
May
June
July
August
September
October
November
December
Max
1988
Min. Mean Max.
1989
Min. Mean
1925-89
Mean 1988 1989 1925-89
29.2
26.2
27.3
22.5
19.2
16.1
r4.9
16.1
19.9
22.2
22.7
21.5
11.4
15.5
17.4
12.9
12.6
10.1
9.1
9.1
13.3
t2.2
12.9
16.0
23.30
20.85
20.35
t7.10
15.90
13.10
12.00
12.60
16.60
r1.20
1,7.50
2t.75
27.6
29.0
26.8
22.2
18.3
13.5
t3.7
13.8
11.9
19.6
25.0
21.2
t7.5
t7.4
18.3
14.0
tr.7
1.6
-at.)
t.3
9.9
10.8
14.3
r6.4
22.55
23.20
22.55
18.10
15.00
. 10.55
10.50
10.55
13.90
15.20
19.6s
21.80
22.17
22.38
20.64
t7.41
r4.43
rt.92
11.04
11.99
13.61
1.5.72
18.40
20.52
32.6
23.4
28.2
15.0
r20.6
i 13.6
t 6.4
60.0
66.4
14.8
44.6
31.0
2.6
1.6
2.8
54.0
97.0
104.8
87.0
88.8
51.8
38.2
33.8
t3.4
23.04
r9.7 4
26.32
52.36
78.63
7 6.17
89.52
76.44
63.06
50.52
34.83
29.51
33N1
Block I
Block II
Blockltr
BlockIV
Figure 3.1.L Plan of experiment 1 and details of treatments:
A= Beecher,
F= Currency,
B= Forrest,
G= Tiga,
C= Coolabah, D= N.Z CaPe, E= Saia,
H= Languedoc, I= Namoi, J= PoPanY
JDGBCEAHFI
DEJGAFBHIC
JHDABEIGCF
JFGEHCAIDB
34
3.I.3 RESULTS
3.1.3.1 Plant Establishment
Seed weights differed markedly (fable 3.1.2) and as a result there were differences
between cultivars in the number of plants established (Iable 3.1.3).
Sowing rates were aimed at 100 kg/ha based on pure germinating seed, however
despite prior calibration of the drill, there were some discrepancies. Actual sowing rates
were calculated by the difference between initial weight of seed and fînal weight of seed
having regard to distance travelled by the tractor beyond the planned area of the plots.
There were significant differences in the number of plants/m2 of barley, oats and
triticale cultivars and vetch species (Table 3.L.4). Significantly higher number of plants was
recorded in the plots of oat cultivars and vetch species cvs. Namoi and Popany. There was
no significant difference in plant number benveen vetch species cvs. Languedoc, Namoi and
Popany or Tiga triticale. Similarly there was no significant difference in plant number
between vetch species cvs. Languedoc, Popany and triticale cvs. Currency and Tiga. The
plant number of barley varieties Beecher and Forrest was significantly lower than oats and
triticale cultivars or vetch species. Also there was no significant difference in plant number
within barley cultivars.
3.1.3.2 Dry Matter Yield
It is obvious from Table 3.1.4, that there were significant differences in DM yield
between cereal cultivars and vetch species at various stages of growth. Vetch species cv.
Languedoc produced consistently higher DM yield throughout the season, except 147 days
after sowing when there was no significant difference between yields of the cereal cultivars
and vetch species. The other species of vetch cvs. Namoi and Popany were not consistent
in DM production during the season but generally were higher in DM production than
cereals.
Among cereal cultivars Coolabah oats and Currency triticale produced similar DM yield to
that of vetch species 36 days after sowing. However, after this stage Coolabah oats
Table 3.1.2. Mean seed weight, purity, germination and number of pure germinating seeds per kilogram of cereals, vetch
and medic cultivars used in the field experiments at Waite Institute.
Year Species Cultivars Mean seed weight PuritY Germination Puregerminatingseeds
1988
1989
B arley (H or deum v uI g ar e)
Oats (Avena sativa)
Oats (Avena strigosa)
Triticale (X Tritico s e cale)
Medic (M edic ago s cutellata)
Vetch (Vicia sativa)
Vetch (Viciavillosa)
Vetch (V i c i a b e ng hale nsis)
Oats (Avena sativa)
Vetch (V icía benghnlensis)
Beecher
Forrest
Coolabah
N.Z cape
Saia
Currency
Tiga
Sava
Languedoc
Namoi
Popany
Coolabah
Dolphin
Popany
Namoi
s2 (11.40)
48 (11.06)
31 (11.35)
22 (t0.72)
19 (t0.63)
51 (r1.33)
20 (tr.26)
21 (10.55)
65 (11.31)
40 (!r.26)
4r (t1.41)
31 (t1.3s)
31 (t1.25)
4r (+1.47)
40 (!1.26)
9s
98
92
82
87
98
92
82
96
89
93
8s
80
92
94
98
98
99
99
99
99
97
91
99
97
98
98
99
98
97
20,600
21,700
35,400
56,000
61,100
20,200
56,000
63,800
16,200
29,000
26,800
38,700
40,700
27,t00
27,400Vetch (Vlciavillosa)
36
Table 3.1.3. Expected and actual plant establishment of barley'
oats, triticale and vetch cultivars when sown as forage crops.
Species/Cultivars Plant establishment (number / m2)
Expected Actual 7o Establishment
Barley
Beecher
Forrest
Oats
Coolabah
N.Z. Cape
Saia
Triticale
Currency
Tiga
Vetch
Languedoc
Namoi
Popanv
173
183
336
36r326
241
256
86
79
96
79
7l
84
76
348
454
468
20r229
284
333
285
362
3r7
86
83
81
247
304
259
and Currency triticale were significantly lower in DM production than Languedoc vetch
during the season. Also Coolabah oas produced high DM yield consistently within cereal
cultivars throughout the season. On the other hand barley (cvs. Beecher, Forrest), oats (cv.
N.Z cape) and triticale (cv. Tiga) consistently produced lower DM yield than other cereal
cultivars during the season.
3.1.3.3 Flowering
The various cultivars of cereals and vetch species differed in time to flowering. In these
species days to flowering were recorded as follows: barley cvs. Beecher and Forrest 110;
triticale cvs. Currency 96, Tiga 135; oats cv. Coolabah 121 and vetch species cvs.
Languedoc 91, Namoi 99 days after sowing respectively. The flowering date of N.Z. Cape,
il{ìt'
J
37
Saia oats and Popany vetch was not recorded. Flowering had not commenced 135 days
after sowing in these three species.
3.1.3.4 Crude Protein Percentage
Significantly higher crude proæin percentage was recorded in vetch species than
cereal cultivars (Table 3.1.4) but there was no significant difference in protein percentage
between vetch species. Similarly there was no significant difference in protein percentage
between cultivars of oats or triticale. There was also no significant difference between
cereal cultivars of barley cv. Forrest oats cvs. Coolabah, N.Z. cape and triticale cv.
Currency or within barley cultivars Beecher and Forrest.
3.1.3.5 Crude Protein Yield
There were significant differences in crude protein yield between cereal cultivars
and vetch species (Table 3.1.4). The crude protein production was significantly higher in
plots sown with vetch species. However there was no significant difference in crude
protein yield between Popany vetch, Coolabah oats or Tiga triticale. Similarly there was no
significant difference in crude protein yield between Forrest barley, oat cultivars Coolabah,
N.Z. cape, Saia and triticale cvs. Cunency and Tiga. There was no significant difference in
crude protein yietd of barley cultivars Beecher and Forrest, oat cv. N.Z. Cape and triticale
cv. Currency.
*
{ ---.æ
Table 3.I.4. Density, yield, crude protein content and crude protein yield of cultivars of barley, oats, triticale and vetch'
transformed data 1n are the means of data, content
matter (kg/ha
Beecher
ForrestOats
Coolabah
N.Z. cape
SaiaTriticale
Currency
Vetch soeciesLanguedoc
Namoi
Popany
(#lnÊ)
s.14(173)
s.19(1 83)
s.87(336)
s.88(361)
s.71(326)
s.47(24r)
s.s3(2s6)
s.s0(241)
s.7 r(304)
5.s5(259)
36
4.36(78)
4.28(73)
4.65(10s)
4.2s(70)
4.r7 (6s)
4.74(177)
4.36(79)
4.86(129)
4.76(116)
4.s4(9s)
65
s.80(330)
s.13(313)
6.33(s74)
6.11(4s3)
6.17(493)
6. rs(495)
s.8 i (339)
6.7s(865)
6.83(e46)
6.51(676)
8.60(s466)
8.63(s706)
8.78(6571)
8.58(s38s)
8.s9(s423)
8.70(6184)
8.s6(s256)
8.7s(63r7)
8.83(6816)
8.97(7863)
8.64(s812)
8.93(7s97)
9.06(8664)
8.e0(738s)
9.16(9674)
8.99(817s)
8.s8(7100)
content
5.48
6.78
9.r4
9.43
10.86
7.70
10.95
26.3r
23.57
25.67
s.84(3s3)
6.11(469)
6.s3(737)
6.24(s61)
6.6e(834)
6.48(676)
6.69(806)
1.82(2s3r)
7.s4(1933)
7.22(1768)
(Days after sowing)93
7.08(1208)
1.r3(r274)
7.41(1678)
7.23(1408)
7.30(1s08)
1 .37 (1599)
6.98(1101)
8.13(3419)
8.20(3680)
8.04(3101)
9. r6(9857)
8.es(7785)
9.20(10031)
2r t41
Tiga
n.s. = not significant; ,(t<t<-p<0.0010.31 0.2
n.s.
3.52 0.68
*J< r< *<* r< {<**Level of ***c
0LSD 0 0.31
:
39
3.1.4 DISCUSSION
Small grains have been used in various regions of the world as a source of forage
for animal production (Stephen et at.1977; Ciha 1983). In general higher forage yield from
cereals is possible in good growing conditions e.g. the use of proper sowing rate, adequate
soil moisture and nutrients. In this Waite Institute study the growth pattern of cereals
suggests that herbage production from cereal cultivars was severely restricted by nitrogen
availability compared to vetch species (Table 3.1.4). With the application of nitrogen
fertilizer to the cereal component of the experiment the differences in DM production
between cereal cultivars and vetch species disappeared. Spurway et al. (1974) reported
more than 50 percent increase in oats DM yield with the application of nitrogen fertilizer'
The higher protein percentage obtained from vetch species compared to cereals is
due to species differences (Ciha 1983). The small differences in the percent crude protein
within cereal cultivars agree with the findings of Brown and Almodares (1976), Stephen er
al. (1977) and Cannell and Jobson (1963). Also the species used in this study were
different in the time to reach heading and maturity. The low protein percentage of barley
cultivars compared to other cereal cultivars may be due to maturity differences. A decrease
of up to 60 percent in the crude protein content of cereal from the flowering up to the dough
stage have been recorded by Gross (1947). On the basis of the evidence available to choose
the best of these cereals and vetch species oats cv. Coolabah and Languedoc vetch produced
consistently higher DM yield during the season.
T
i,{,|:Í¡
tII
I
l
3.2 Experim ent 2z The effects of sowing rate on yield and
protein content of oats, medic and vetch forage crops
3.2.I INTRODUCTION
In temperate and Mediterranean environments of Australia, animal productivity is
limited in early winrer by the slow growth of improved pastures during establishment and
both low quantity and quality forage of native pastures. McFarlane (1965) reported green
herbage availability was less than 1000 kglhaon well fertilized improved pastures, when
stocked at medium rates and that the gfowth rate of such pastures, on average, was less
than 6 kglhatday during early winter. Both improved and native pastures are ineff,rcient in
producing early winrer herbage and this limits their potential to support high levels of
animal production.
Annual forage crops, particularly oats, are used to increase the supply of green
feed during early winter months in cool temperate environments (Crofts et al.l9l0; I-ewis
l9S8). This evaluation of forage crop potential for winter feed supply has generally been
based on cereals. Little attention has been given to annual forage legumes as an alternative
to cereals. Legume crops have the advantage of maintaining soil fertility (Spurway er a/.
1976) and generally grow better in nitrogen-deficient soils than cereals. In addition,
legumes are superior in feeding value (in terms of animal production response) and
nutritive value (animal production response per unit of intake) to grass species (Campling
1984; Thomson 1984).
On the other hand research has suggested that high sowing rates can increase
early winter productivity of pastures and forage crop species and hence fill the autumn-
winrer feed gap (Crofts 1966a; Robinson and Sykes L973; Kemp 1974; Southwood et al.
lg74). This may permit greater livestock carrying capacity on a farm and possibly more
effective utilization of surplus pasture growth at other times of the year.
I
I
41
The field experiment reported in this section was designed to assess the impact of
density on yield and protein content of oats (Avena sativa) cv. Coolabah and an annual
medic (Medicago scutellata) cv. Sava and vetch (Viciabenghalensls) cv. Popany.
3.2.2 MATERIALS AND METHODS
GermirntíonTests: Similar standard techniques Myers (1952) as mentioned in the
Materials and Methods of Experiment I were used to ensure that the same weight of viable
seed was sown at each of six sowing rates (1, 5, 10, 50, 100 and 500 k/ha). These
sowing rates will be referred to as Dl, D2,D3,D4, D5 and D6 respectively.
Design of Experiment: The experimental design was a split plot with four
replications and plot size was 2.5m x 4.0m with plot-to-plot distance of 50cm. The
species were main plots and sowing rates were sub-plots. The main plots were
randomized within each replicate and the sub-plots within each main plot. Hence a total of
72 plors were sown (Densities (6) x species (3) x Blocks (4)). The data were analysed as
a split plot design. The lay out of the experiment is given in Figure 3.2.1.
Seed Treatment: The seed of medic and vetch was inoculated with group "4" or
WSM (Rhizobium trifolii) and "E" or SU 319 (Rhizobium leguminosarum) cultures
respectively. Oat seed was pickled with LE-SAN-EL (Fenaminosulf a.i 50g/kg) to restrict
fungal infections of seedlings.
Seedbed Preparation: The site at Waite Agricultural Research Institute was sown
to triticale in the previous year. The detailed information about the site/soil type is
presenred in section 1.2 and rainfall data is given in Table 3.1.1. The soil preparation was
done with tractor and sca¡ifier. In addition, plots were hand hoed before sowing to loosen
the soil. A fertilizer mixture of single superphosphate and lime at the rate of 100 kg/ha
each was broadcast by hand in each individual plot before sowing. Urea was broadcast
onto the oat plots on September 1 1988 (stem elongation stage) at the rate of 50 kgN/ha.
42
N
1Block I
Oats
Block IIIVerch
Verch MedicBlock II
Verch
Block IVMedic
Oats Medic
Medic Oats Vetch
Figure 3.2.1 Plan of experiment 2 and details of treatments:
Dl = lkg seed/ha, D2 -- 5kg seed/ha, D3 = 10kg seed/ha,
D4 = 50kg seed/ha, D5 = 1ü)kg seed/ha, D6 = 500kg seedlha.
Oats
D6D1D1D5D4D1
D5D3D+D1D1D+
D2D2D2D4D5D3
ND5D6D2D2D2
D1D4D5D3D6D6
D3D6D3D6D3D5
D1MD2MD4D1
D3D6D3D3D3D5
MD2D4D6D6D3
D6D5D1D5D1D6
D5D3D6D1D5D2
D2D1D5D2D2D4
43
Sowing Details: Plots were sown on June 16, 1988 by hand broadcasting and all
plots were hand-raked uniformly to cover the seed.
Insecticide andWeeding: Larsban was sprayed at the rate of 350rnl per hectare for
the control of sitona weevil (Sitona hwneralis) in medic and vetch plots on July 7, 1988.
The lower density (Dl, D2, D3) plots were hand hoed after the second harvest to remove
weeds in all three species.
3.2.2.1 Data Collection
Plant Establishment Counts: Establishment counts were made 45 days after
sowing. Plants in each of four quadrats per plot were uprooted, and counted in all
treatments except Dl. For this lowest density the number of plants in the entire plots of all
three species were counted. At the time of the second, third and fourth harvests, several
plants (between 2 and 16) were uprooted from the quadrat area of all the densities except
Dl. These plants were counted and dried at 85oC for approximately 24 hours. The dry
weights of these plants were divided by their respective plant number and dry weight per
plant obtained. The samples were added back to the harvested material and total dry
weight measured. The total weight was divided by the respective plant dry weights and
plant number esrimated. AtlHZ dry matter yield of weeds was included in the total dry
weight (Sown species + weeds dry weight) which was divided by plant dry weight in
order to obtain plant number. At H3, H4 the dry weight of sown species only was divided
by plant dry weight. The plant number of Dl was not estimated during H2,H3 and H4-
Harvest Dates: Four harvests were taken throughout the experimental period on
July 31 (H1), August 28 (H2), September 25 (H3) and October 26 (H4), which were 45,
73,IOl and 132 days after sowing respectively.
Quadrat size: Atthe time of the first harvest four quadrats per plot each of size
15.0cm x 33.3cm were used. At the time of the second, third and fourth harvests two
quadrats per plot each of size (55cm x 60cm) were used.
44
Dry MatterYietd: Seedlings from each quadrat (15.0cm x 33.3cm) were han'ested
from each density. The seedlings were washed, dried with tissue paper and kept in the
oven at 85"C for approxima tely 24 hours. Two seedlings from Dl plots of each species
were dried and weighed. The total dry matter per square metre for the Dl plots was
subsequently calculated by multþlying the plant dry weight by the plant number per square
metre of all the three species. Larger quadrats (55cm x 60cm) were used for the second,
third and fourth harvests. Plants from a quadrat in each half of all plots were harvested.
Two to sixteen plants were uprooted at the time of each harvest for single plant dry weight
estimation. The remaining plants within these quadrats were cut to gtound level with a
knife and all the samples from both quadrats within each plot were bulked. At H2 the
entire sample was dried in an forced-draught dehydrator at 85oC for approximately 24
hours and the dry weight subsequently determined. In the case of H3 and H4 the bulked
samples from the field were shaken free of soil and subsampled. These subsamples were
placed in a refrigerator at 2 to 5oC for up to three days, when they were separated into
weeds and sown species and dried as above. The dry weight of the subsamples varied
from 30 to 70g. The dry weight of both separated species was added back to the sample
from which each subsample was taken. The dry weight of each species was calculated in
the following manner.
Weight of harvested material from the field = DMtot
V/eight of subsample = DMss
V/eight of the remainder of sample = DMror- DMss - DMns
Weight of sown species in subsample = DMovv
Weight of weeds in subsamPle = DMw
Hence the total dry weight (DMroJ = DMss + DM¡5 and DM55 = Dl\{e¡ay + DMvv
Now, weight of sown species = DMTorx DMg¡ay + DM55
and the weight of weeds = DMlo¡x DMw + DM55
Plant nitrogen analysis: After the final harvest samples of the sown species were
retained and the total plant nitrogen measured. The procedure for onward processing of
these samples is given in the Materials and Methods section of experiment 1.
45
3.2.3 RESULTS
3.2.3.1 General
Several factors led to irregular plant emergence and yields across the experimental
site. These included in order of importance. (i) the presence of pigeons on the site: some
seed was eaten; (ii) the use of small quadrats at the time of first harvest; (iii) the presence
of weeds on the site and hoeing of the plots; (iv) I-odging occurred in oat plots sown at
higher sowing rates. It is considered that these factors had some effect on the results of
the experiment and will be borne in mind in interpreting the results.
SeedTesting: Germination and purity percentages for Coolabah oats were 92 and
99, for Sava medic 82 and 91, and for Popany vetch 93 and 98 respectively. Grain weight
for oats was 31 (t 1.35)mg, for medic 2l (10.55)mg, and for vetch 41 (f 1.47)mg'
The summary of analysis of variance (ANOVA) of signihcant differences of oats,
vetch and medic for plant number, dry matter (DM) yield (sown species + weeds), percent
crude protein between species, sowing rate and their interaction a¡e given in Table 3-2.1-
Table 3.2.1. Summary of ANOVA, density and total yield of oats, medic
and vetch sown at various sowing rates.
Source of variation Plants/m2
(Days after sowing)
45 73 101 r32
Total YieldA (kgDlvl&a)
(Days after sowing)
45 73 101 132
Species
Sowing rates
Species x.
* * n.s. *
*** *d<* **tl. ***
n.s. n.s. n.s. n.s
*** *,F¡* **¡1. ***
S rates n.s. n.s. n.s. {<
A = Sown species + weeds
n.s. n.s. l'{' n. s.
46
3.2.3.2 Plant Establishment
The number of plants in the entire plot of the lowest density were counted because
of inegular emergence in these plots. There were few plants in these plots and were not at
equal distances which made diffîcult to place quadrat randomly and obtain uniform plant
counts. Also the plant number in these plots were not estimated at subsequent harvests,
hence these figures were not included in the statistical analysis. The number of plants in
the entire plots of the lowest density at Hl was 32 (t 4.1), 36 1+5.4¡ and27 (t3.4) for
oats, medic and vetch respectively.
The mean number of oat plants and medic plants over all densities were not
significantly different from each other 45 and 73 days after sowing (Figure 3.2.2), but
there were significantly fewer plants of vetch at both harvests. By the third harvest there
was no significant difference between species in the overall mean plant number. There
was no significant difference in plant number between oats and vetch or vetch and medic
132 days after sowing.
There was a significantty higher number of plants of oats, vetch and medic per
square metre as the sowing rate increased from 5 to 500 kglha at each of the four harvests
(Figure 3.2.3). The number of plants was similar for sowing rates of 5, 10, 50 and 100
kg/ha between each harvest during the season. However there was a reduction in plant
number with time at the highest sowing rate.
A Sowing rate x Species interaction was observeÅ I32 days after sowing (Table
3.2.2). Plant number of oars were significantly different at different sowing rates. The
plant number of vetch behaved differently. Signifrcantly higher number of plants were
recorded in D6 plots while no significant difference was observed between D4 and D5, or
D2 and D3. There \ryas no signihcant difference in numbers of medic plants at D5 and D6,
while other sowing rates were significantly different from each other. At D4 the number
of oat plants was significantly less than the number of vetch plants. At D5 medic plant
number was significantly higher than vetch plants. Oat plant number did not differ
statistically from plants of both medic and vetch.
500
È ¿1o0
(Ë
È
6 3oo
(A
-oCd
çt)f¡l 2N
**
*
Oats
Medic
Vetch
100
45 73 r01 132
Days after sowingFigure 3.2.2. Overall mean- úlant numbei of oats, medic and vetch at variousitu"æt of growth sown at difïerent rates. The statistical analysis wasp..î*-.don log transformed data. The corresponding data are presented inAppendix Table 5.1.
2000
Sowing raæs(kcita)
'*5+10*so-* 1oo
-.'---..ft 500
045 13 101 r32
Days after sowingFigure 3.2.3. The impact of sowing^rates .on n,l1nt establishment of oats,mõ¿¡c and vetch at várious stages õf growth. The statistical analysis wasp.ito.-"d on log transformed îata. The corresponding data are presentedin Appendix Table 5.2.
NÉØc
-g(¡)tr(r>
-o(Ë(r)
f¡ì
000I
48
3.2.3.3 Dry Matter Yield
Total dry matter yield (Sown species + weeds); There were no significant
differences in the mean total DM production of the three species over all densities
throughout the season (Table 3.2.3).
An increase in the sowing rates resulted in increased DM yield of oats, medic and
vetch 45 and 73 days afrer sowing (Figure 3.2.4). The highest DM yield was produced in
D6 plots. All densities were significantly different from each other except D4 and D5,
which gave similar DM yield 45 days after sowing. There were a number of significant
differences in the mean DM yietd of oats, medic and vetch between sowing rates 101 days
after sowing. Also there was a significant Sowing rate by Species interaction (Table
3.2.4). Maximum DM yield was obtained from D4, D5 and D6 in the case of oats and
vetch while it was minimum in Dl and D2 plots. In medic plots similar total DM yield was
recorded for D1, D2 and D3 while D4, D5 and D6 were significantly different from each
other. By the time of the fourth harvest there was no significant difference in the mean
DM production of oats, medic and vetch between Q2 eD3) or (D4, D5 & D6).
Dry Matter Yield of Sown Species: Table 3.2.5 summarises the ANOVA for
significant differences of sown species DM yield, weeds DM yield and crude protein
percentage between species, sowing rates and Species x Sowing rates interaction. The
mean DM yield of oats, medic and vetch sown at different sowing rates was statistically
similar at both the harvesting stages (Table 3.2.6).
As expected higher sowing rates generally produced significantly greater yields of
oats, medic and vetch. Examples of overall trends are shown in Table 3.2.7. However,
there were some discrepancies in the data resulting from heterogenity of sampling sites for
reasons already given in3.2.3.1.
1 0000Sowing rates
# l(kg/ha)
*5u#10rr*50rrll- r00 'i,
ìt- 500 '!,
6000
4000
2000
040 60 120 140
Figure 3.2.4. The effects of sowing rates on the mean yield of oats,
medic and vetch at various stages of growth. The statistical analysiswas performed on log transformed data. The corresponding data is
presented in Appendix Table 5.3.
8000
6E
=ôEt-v
!!
80 100
Days after sowlng
50
Tabte 3.2.2. The effects of sowing rates on density (plants/m2) of oats,
medic and vetch 132 days after sowing.
transformed data: figures in pa¡enthesis a¡e the means of orieinal data)
Sowing rates
(ks/ha)
Species Mean
Oats Medic Vetch
5
10
50
100
500
2.60(14)
3.2s(2s)
4.7r(1r2)
s.s6(26t)
6.16(503)
2.e3(18)
3.4s(35)
s.18(182)
5.84(3s4)
596ø04\
2.e6(20)
3.38(2e)
s.30(204)
s.33(212)
5.93(380)
2.83(1s)
3.36(2e)
s.06(166)
s.s8(27s)
6.0rø29\
Mean 4.46083\ 4.67(r97\ 4.58(169)
Sowing rate ***
Species *
Sowing rate x Species *
For means within same sowing rate. LSD G=0.05) = 0.38
Tabte 3.2.3. The average effects overall sowing rates on yield of oats,
medic and vetch at various stages of growth.
tran sformed data: figures in parenthesis are the means of original data)
LSD (P=0.05) = 9.39
LSD (P=0.05) = 6.17
LSD (P=0.05) = 9.43
Species Yield (kgDffia)(Days after sowing)
45 73 101 r32
Oats 4.s2(240) 6.21(86s) 2349
Medic 4.6s(312) 6.17(1131) 24s7
Verch 4.43(307) 6.04(1030) 24s3
8244
7651
8078
LSD n.s. n. s. n. s. n.s.
51
Table 3.2.4. The effects of sowing rates on total yield (kgDM/ha) of oats,
medic and vetch 101 days after sowing.
Sowing rates
(kg/ha)
Species Mean
Oats Medic Vetch
1
5
10
50
100
500
1574
1668
2054
2636
2892
3272
1404
1118
1708
2628
3514
437t
t3322004
2208
2677
3r63
3333
1437
t596
r990
2&73190
3658
Mean 2349 2457 2453
Sowing rates '. ***
Species
Sowing rate x Species :Ft<
For means within same sowinrrate
LSD (P=0.05) = 551
n. s.
LSD (P=0.05) =749LSD (P=0.05) = 654
Table 3.2.5. Summary of ANOVA for yield of sown species and weeds in
plots of oats, medic and vetch sown at various rates.
Source of variation Sown species DM yield
(Days after sowing)
101 132
Weeds DM yield
(Days after sowing)
101 132
Species
Sowing rates
n. s.
*rF )k
n.s.
n. s.
***
n.s.
***
n.s.
n.s.
***
n.s.
{.
Species x Sowing rates
52Table 3.2.6. Overatl yield of sown species (oats, medic and vetch) at two
stages of growth when these species were sown at different rates.
(Log transformed data for the fîrst stage, f,rgures in parenthesis are the means of original
data (keDlvÍha))
Days after sowing Species
Medic
LSD (P=O.05)
Oats Verch
101 6.68(1332) 6.81(1738) 6.77(1479) n.s.
n.s.t32 6130 5468 6t34
n.s. = non significant difference between species
Dry Matter Yield of Weeds:Tltere were significant differences in the incidence of
weeds in plots of oats, medic and vetch sown at various rates 101 days after sowing
(Tables 3.2.5 and 3.2.8). Maximum yield of weeds was recorded in the case of oat plots,
but this was statistically different from vetch plots: however, medic plots had a
significantly lower yield of weeds than oats or vetch. No significant differences were
observed in the yield of weeds in plots of all the three species 132 days after sowing.
There were significant differences in the mean yield of weeds in plots of oats,
medic and vetch when these species were sown at various sowing rates 101 days after
sowing (Table 3.2.9). There was no significant difference in the DM yield of weeds
between lower densities (D1, D2, D3, D4). The D6 plots produced significantly lower
yield of weeds from other densities but was similar to D5. Similarly the mean DM yield of
weeds in plots of the three species under different sowing rates behaved significantly
different from each other 132 days after sowing. The DM yield of weeds was inversely
proportional to the sowing rates. Significantly higher weeds DM yield was obtained in
case of Dl and D2 while it was significantly lower in plots of D5 and D6. Also there was
no significant difference between @1 and D2) or (D5 and D6). The other densities were
signihcantly different in the DM yield of weeds from each other.
53
3.2.3.4 Crude Protein Percentage
Significant differences were observed in the mean crude protein percentage
between species, sowing rate and their interaction (Table 3.2.10). The overall mean
protein content of oats, medic and vetch sown at different rates was significantly different
from each other. The protein content of vetch was signiflrcantly higher than the mean
protein percentage of oats or medic. Similarly, the mean protein percentage of medic was
significantly higher than oats. The protein percentage of vetch at all sowing rates was
consistently higher than medic and oats. There was no significant difference in protein
percentage of vetch between different sowing rates. However, the protein percentage of
medic and oats at 1 and 500 kg sowing rates/ha were significantly lower than the protein
percentage of these species at other sowing rates. The protein percentages of both oats and
medic at low sowing rates (i.e. 1, 5 and 10 kg,/ha) were statistically similar, while the
protein percentage of oats was significantly lower than medic at 50, 100 and 500 kg seed
rutelha.
Table 3.2.7. The effects of sowing rates on the overall yield of sown
species (oats, medic and vetch) at two stages of growth.
(Log transformed data for the first stage, figures in parenthesis are the means of
orisinal data)
Sowing rates(kdha)
Yield (kgDlvl/ha)(Days after sowing)
101 t32
1
5
10
50
100
500
s.17(r98)
s.s7(287)
6.36(622)
7.s2(1900)
7.72(2s22)
8.17(3570)
98s
3102
4754
7986
9r52
9487
LSD .05) 0.40 093I
54
Table 3.2.8. Mean yield of weeds in oats, vetch and medic plots at two
stages of growth when these species were sown at different rates.
Days after sowing Species
Medic
LSD (P{.Os)
Oats Verch
(kÐlvf/ha)
101
r32
1017
2rt3
719
2183
974
t943 n.s.
249
Table 3.2.g. The effects of sowing rates (mean of oats, medic and vetch)
on the dry matter yield of weeds at two stages of growth.
Sowing rates(kg/ha)
Yield (kgDlvlha)(Days after sowing)
101 r32
1
5
10
50
100
500
t238
1310
1368
747
668
89
4208
3866
2782
1202
230
19l
LSD (P=0.0 5) 629 10 18
55Table 3.2.L0. The effects of different sowing rates on the crude protein
percentage of oats, medic and vetch 132 days after sowing.
Sowing rates(ke/ha)
Species
Medic
Mean
û¿ts Verch
1
5
10
50
100
500
9.68
8.6r
10.84
7.85
7.81
6.95
7.70
lt.6413.69
11.73
13.10
11.68
24.93
24.15
24.28
24.59
26.88
24.94
14.10
14.80
16.27
t4.72
15.93
r4.52
Mean 8.62 11.59 24.96
Sowing rates n.s,
Species ***
Sowing rates x Species *LSD (P=0.05) = 2.36
LSD (P=0.05) = 3.46
LSD (P=0.05) = 3.08For means within same sowing rate.
3.2.4 DISCUSSION
The significant difference in plant number at different sowing rates is self
explanatory. As the sowing rate increased the density increased: however, the difference
in density of oats, medic and vetch need explanation. The lower density of plants in vetch
plots compared to the plots of medic and oats was due to the larger seed size of vetch.
This resulted in a lower number of plants per squale mere.
The seed weight of oats and medic also differed: oats seed is larger than medic but
in this study both species had the same plant number. The probable reason for the higher
number of seedlings/m2 of medic after emergence may have resulted in higher plant
mortality in early srages. Adem (1977) reported self-thinning in high densities (50G'lmO
kg seed/ha) of Medicago specles as early as seedling establishment. Here the reported
counting was made 45 days after sowing. Furthermore the use of small quadrat at the time
of Hl and irregular emergence of oats, medic and vetch because of broadcasting sowing
may have some effect on the results.
The reduction in plant density with time at high sowing rate is in agreement with
earlier reports (Yoda et al. 1963; V/hite and Harper l97O; Bazzaz and Harper 1976) and
56
the phenomenon has been reported as changes in plant population or self-thinning (Tadaki
and Shidei 1959; Yoda et aI. 1963). Similarly Puclaidge and Donald (1967) found some
mortality among wheat plants at a sowing density of 184 plants/m2. In contrast to this
Harper and Gajic (1961) found no significant density-dependent mortality in population of
Agrostemma githago when they sowed A. gitltago at rates of 0, 1,076, 5,380 and 10,760
seeds per m2 either alone or with 120 or 600 wheat grain or 24 or l2O sugar beet clusters
per m2. However, they found a reduction in the $owth rate of individual plants and a
gfeater proportion failed to ripen seed.
In the 1988 Waite Institute experiment, the higher number of seedlings per unit
area was associated with the maximum dry matter yield from the higher sowing rates in the
early stages of growth. Similar results for increased dry matter production with increased
sowing rates were reported by Crofts (1966b) and Robinson & Sykes (1973) on the
cenrral tablelands of New South Wales. Crofts (1966b) found that sowing rates of 97.5 to
244 kg/ha increased winter dry matter yield more than four fold. Similar dry matter
production from the medium sowing rates towards the end of the season support the
resulrs of Donald (1951, 1954), who found that final dry matter yield was found constant
from moderate to high densities in subteranean clover.
This thesis study has shown that increasing crop density strongly reduced yield of
weeds and this is in agreement with earlier experiences in cereals (Ervio 1972; Barret and
Campbell 1973; O'Donovan and Sharma 1983; Medd et al.1985). These authors reported
reduced effects of some broadleaf weeds, ryegrass and wild oats (Avena spp.) by
increasing cereal crop density.
As expected the mean protein percentage of oats was significantly lower than
medic and vetch. The reported protein contents of oats and medic varies greatly. Some
workers (e.g. Smith 1960; Gardner and rWiggons 1961; Brundage and Klebesadel 1970;
Tingle and Dawley 1974) reported from 9.2 to 10.0 percent crude protein in oats. Others
(e.g. Radcliffe and Cochrane 1970; Launders 1971 and Adem L977) working with annual
medics found crude protein percentâges from 10.5 to 19.8. Ahlgren (1956) and Acikgoz
et at. (1985) recorded crude protein percentage from 13.30 to 22.92 in vetch herbage. Our
57
results for crude protein percentages of oats, medic and vetch are in general agreement
with the results of these workers.
The finding thar sowing rates generally had no significant effect on the crude
protein content of oats, medic and vetch disagrees with the results of Donald (1951) who
reported a decrease in nitrogen content of Wimera ryegrass from 1.84 to 1.03 at plant
densities from 12.5 to 40,500/m2 at 2LO days after sowing. The lower crude protein
content of medic at I kg sowing ratelha than the other sowing rates may be due to the
shattering of pods or leaves in these plants. Similarly, lower crude protein percentage of
oats sown at 500 kglhathan the other sowing rates may be because of lodging which may
have caused leaf senescence and rottening, shattering, or a higher proportion of individual
plants in this population failed to ripen (Harper and Gajic 1961).
ülì
,ì
4
i'
lr
t
3.3 Experiment 3: The effects of different sowing ratios on
herbage yietd and protein content of oats' vetch and medic
3.3.1 INTRODUCTION
Grazing systems throughout temperate regions of the world are characterised by
relatively constant year-round stocking rates (Willoughby 1970). During the summer the
dry pasture in western and southern Australia is of low quality (Arnold et al. 1974), and
supplementation with hay, grain or standing crops is necessary to maintain livestock gain.
Therefore fodder conservation is widely practised in southern Australia (Radcliffe and
Newbery 1968). Investigations designed to evaluate the potential of forage crops for hay
production have generally been based on only one species at any one time. The most
commonly used species has been oats. Unfortunately oats and other cereals after
inflorescence emergence have low protein contents (Nicholson 1957). While rations
containing from 13 to 2OVo crude protein are required for livestock (Walton 1980). The
inclusion of legumes (e.g. lupins, medic and vetch) in a winter small grain crop has
porenrial for the improvement of forage quality @belhar et al.1984; Bowdler and Lowe
1930). An experiment was designed in 1988 to assess the herbage dry matter yield and
nutritive value of oats plus medic and oats plus vetch in various mixtures.
The experiment was sown at Waite Agriculture Research Institute farm. The site
grew to wheat and oats in 1986 and 1987 respectively. For detailed information about the
site and soil type see section 1.2, rainfall data are given in Table 3.1.1.
3.3.2 MATERIALS AND METHODS
Design of Experiment: The experimental design was a split plot with four
replications. There were five sowing ratios of oats (Avena sativa) cv. Coolabah:vetch:
(Vicia benghalensis) cv. Popany and Coolabah oats:medic (Medicago scutellata) cv. Sava
each (0:1ü),25:75,50:50, 75:25,100:0). Plot size was 1.8 m x 18.0 rn with row spacing
of 15 cm. The plan of the layout of the experiment is given in Figure 3.3.1.
.'Irl,l
'':;I
II
i
I
59N1
üI
ECADBJFGH
Block IVIDABECJ
FHI
--
Block IIIGJGFHIDEAB
Block IICJ
GHFIDBCE
Block IA
Figure.3.3.1 Plan of exper¡ment 3 and details of treatments:
tII
I
Oats:vetch sowing mixture:A = oats:vetch = 0:100,C=oats:vetch=50:50,
Oats:medic sowing mixture:F = oats:medic = 0:100,H=oats:medic=50:50,
B = oÍrtslvetch=25:75,D = oats:vetch = 7 5:25, E = oats:vetch = 100:0
G=oats:medic=25:75,I = oats:medic =7 5:25, J = oats:medic = 100:0
T
60
Seed Inoculation: The same strain of Rhízobùttn species were used in inoculation
of medic and vetch as reported in the Materials and Methods Section of Experiment 2-
Sowíng Details:Plots were drilled on 8 June, 1988. Sowing rates were based
on viable seed, which were determined before the experiment from the mean seed weight,
purity and germination percentage of the seed. The information is given in the Materials
and Methods Section of Experiment 1. A basal dose of supherphosphate @ 240kglha was
drilled in all experimental plots. Oats, vetch and medic seed were weighed and mixed
according to the sowing ratios described above. A Connor-Shea drill with disc coulter,
coil tyne and Baker boots was used to sow the experiment. The drill was adjusted for
oats, vetch and medic pure and mixed stands as follows in order to release approximately
lffi kg sowing rate/haof these species (Appendix Table 5.4).
3.3.2.L Data Collection
Plant Establishment Counts: Plant establishment counts were made 33 days after
sowing. The number of plants in eight quadrats each of size 30.0 cm x 33.3 cm were
counted in each plot.
Harvest Dar¿s: To estimate herbage dry matter (DM) yield the plots were sampled
five times throughout the season. Harvests were taken on 11 July (FIl), 9 August (H2)' 6
September (H3),4 October (H4) and 2 November (H5). These harvests were 33, 62,90,
118 and 147 days after sowing respectively.
Quadrat Sizes : At H I and H2 eight quadrats each of size 30.0 cm x 33.3 cm were
used. At H3 four quadrats each of size 55 cm x 60 cm were used, while atH4 and H5
four quadrats each of size 0.5 m x 1.0 m were used.
Dry Matter Yield: Plants within each quadrat were cut at ground level and all the
samples from each plot were bulked at each harvest. These samples were brought to the
laboratory. At the time of Hl and H2 the whole sample and at the time of H3, H4 and H5
subsamples were sepÍrated into oats and vetch or oats and medic following the procedure
as mentioned in the Materials and Methods Section of Experiment2.tI
;
t
61
Plant Nitrogen: Samples from the last harvest were processed for plant nitrogen
estimation and the same procedure as mentioned in the Materials and Methods Section of
experiment 1 was followed fo, nit ogen analysis and protein determination.
3.3.3 RESULTS
3.3.3.1. Plant Establishment
The mean plant density of oats was significantly higher than the mean plant
density of vetch (Table 3.3.1). The density of oats increased significantly as the
percentage of oat seed increased from 25 to 100 in the sowing mixture. Similarly, vetch
plant density increased as vetch percentage increased from 25 to 100 in the sowing
mixture: however, there was no significant difference when vetch seed was 75 or 100
percent in the sowing mixture. Also the mean plant number of oats and vetch at various
sowing ratios varied significantly (Table 3.3.2). The plant density of vetch in the pure
stand was significantly lower than the pure stand of oats or oats plus vetch mixed stands.
There was no significant difference in the plant density of pure stands of oats or oats plus
vetch mixed stands.
There was no significant difference in mean plant number of oats plus medic
sown as pure and mixed stands (Table 3.3.2). The overall mean plant density of oats was
significantly higher than the mean plant density of medic (Table 3.3.3). The plant density
of both oats and medic increased significantly as the proportion of seed of these species
increased from 25 to 100 in the respective sowing mixtures.
I
62Table 3.3.1. Density of oats and vetch sown as pure and mixed stands
when the data was statistically analysed for oats vs vetch species
differences.
Oats or vetch percentage
in the sowing mixture
Species þlants/m2)
Oats Verch
25
50
75
100
93
r54
2r9
299
50
118
t94
2t2
Mean 191 r43
Species
Species
***
*
LSD (P=O.05) = 19
LSD (P{.05) = 33x Sowing ratios
Tabte 3.3.2. Mean plant density of oats:vetch and oats:medic sown as
pure and mixed stands when combined data of oats plus vetch and
oats plus medic was statisticalty analysed for differences at various
sowing ratios.
Sowing ratios Species lplans/m2)
Oats:VetchMedic Oats:Vetch Oas:Medic
0:100
25:75
50:50
75:25
100:0
2t3
287
27r
269
299
260
279
284
302
297
LSD (P=0.05 ) 35 n.s
63
Table 3.3.3. Density of oats and medic sown as pure and mixed stands
when the data was statistically analysed for oats vs medic species
differences.
Oats or medic percentage Species þlants/m2)
in the sowins mixture Oats Medic
25
50
75
100
89
163
246
297
57
121
189
260
Mean r99 r57
Species
Species
***
***LSD (P=0.05) = 14
LSD (P4.05) = 31x Sowing ratios
3.3.3.2. Dry Matter Yield
Comparison of Oats plusVetch: The mean DM yield of oats plus vetch grown in
mixtures and pure stands was not significantly different in the early part of the season
(Table 3.3.4). With the progressive stage of development, (i.e. 118 days and 147 days
after sowing) there were significant differences in DM yield of oats:vetch between different
sowing ratios. The DM yield of oats plus vetch at sowing ratios of 0:100, 25:75 artd
50:50 was significantly higher than the pure stand of oats, while there was no significant
difference in the mean DM production of oats plus vetch between sowing ratios of 50:50
and75:25 or berween 75:25 and 100:0. Similarly, there was no significant difference in
DM production of oats and vetch at sowing ratios of 0:100, 25:7 5 and 50:50 at this stage
of growth. In addition, the DM yield of oats and vetch was significantly higher from plos
sown with 0:100 or 25;75 oats/vetch sowing ratios than the 100:0 sowing ratio 147 days
after sowing. However there was no significant difference in the DM production between
0:1fi) or 25:75,50:50 and75:25 oats and vetch sowing ratios in the sowing mixture.
64
Table 3.3.4. Yield of oats plus vetch sown as pure and mixed stands'
Sowing ratios Yield (kgDlvl/ha)
(Days after sowing)
62 90 118Oats:Vetch 33 t47
0:100
25:75
50:50
75:25
100:0
410
549
517
468
455
254ø.
2075
2202
2024
2043
7r7l7508
6622
5640
5047
7686
8134
7409
7437
5942
70
95
82
85
81
LSD (P=0.05 ) n. s. n.s. n.s t225 1585
The DM yield of oats plus vetch generally increased significantly with an increase
in seed of these species from 25 to 100 percent in the sowing mixture (Table 3.3.5).
However, there was overlapping in DM production of both the species at some sowing
ratios during the season. The yield data for oats, vetch and oats plus vetch are also shown
graphically in Appendix Figure 5.1 to 5.5. However it should be noted that there was one
missing Vetch plot as a result of heavy rain and the missing value estimation in Table 3.3.4
was based on GENSTAT program and varies from the calculated missing value in Table
3.3.5, it was Table 3.3.5 which formed the basis for the figures in the Appendix.
Comparison of oats plus medic: There were significant differences in the mean
DM yield of oats plus medic sown as pure and mixed stands 118 and 147 days after
sowing (Table 3.3.6). In the early part of the season both oats and medic produced similar
DM yield when sown either as pure or mixed stands. The DM yield obtained from oats
plus medic mixed stands was significantly higher than the pure stand of oats 118 days after
sowing, while rhere was no signihcant difference in the DM yield obtained from pure plots
of oats and medic or between pure plots of medic and oats plus medic mixed plots
(Table 3.3.7). The partern of DM production of oats plus medic changed 147 days after
sowing. The DM yield of medic appeared to reach its maximum around I 18 days after
sowing and then declined in all sowing ratios. A significantly higher DM yield was
obtained from the pure stand of oats than the pure stands of medic.
Table 3.3.S. Yield of oats and vetch at various stages of growth when sown at different ratios in the mixture-
Oats orvetch
percentage in
the sowing
mixture
33
Oats Verch
transforrned data: ln
62
Oats Verch
are the means of
Yield (kÐlvf/ha)
(Days after sowing)
90
Oats Verch
118
Oats Verch
147
Oats Vetch
25
50
75
100
3.4(3r) 2.83(16) s.32(2r7) 4.4s(8s) 6.36(613) 6.46(6s2) 7.80(2513) 7.s1(1e41) 7.89(277r) 7.66(2240)
3.81(46) 3.62(36) s.7s(344) s.16(173) 6.s1(973) 7.r0(r229) 8.27(4043) 7.77(2s79) 8.33(M66) 7.90(2943)
4.22(6s) 4.18(64) s.e3(3S3) s.S0(332) 7.22(1372) 7.28(t462) 8.19(36e9) 8.s1(49es) 8.s4(sle7) 8.s8(5363)
4.36(81) 4.32(7s) 6.11(4ss) 6.06(443) 7.62(2043) 7.83(2626) 8.s2(s047) 8.89(722r) 8.6e(s942) 8.97(78t7)
LSD 0.32 0.2L o.46 0.48 0.55
Note: There was one plot of pqre vetch missing and the missing values were estimated by a GENSTAT program. These estimated values for total (oats
+ vetch) and oats vs vetch slightty differ in different statistical analyses.
66
There was also a significantly higher DM yield in the mixed stands of oats plus
medic than the pure stands of medic. There was no significant difference in the DM yield
of oats and medic sowing ratioó of 50:50, 75:25 and 100:0. Similarly, the DM yield was
not statistically different between oats and medic sowing ratios of 25:75,50:50 and75:25
at this stage of gowth.
Table 3.3.6. Yield of oats plus medic sown as pure and mixed stands.
Sowing ratios Yield (kÐlvVha)
(Days after sowing)
90 118Oats:Medic 33 62 r47
0:100
25:75
50:50
75:25
100:0
398
483
494
499
525
90
95
97
97
92
2421
2528
22t32282
1908
526/.
5626
6049
5612
4369
3301
5155
5847
5977
6787
LSD n. s. n.s. n.s tt44 1355
The DM yield of both oats and medic increased with increased seed ratio of these
species from 25 to 100 percent in the sowing mixture for the respective species
(Table 3.3.7). The DM yield obtained from oats was overlapping each other at various
sowing ratios throughout the season. The signifîcant increase in the DM yield of medic
with increase in seed rate from 25 to 100 kg/ha in the sowing mixture was consistent at
various stages of growth except 118 days after sowing when mixtures with 50 and 75
percent medic seed produced similar DM yietds. The yield data for oats, medic and oats
plus medic are also shown graphically in Appendix Figures 5.6 to 5.10. In Figure 5.10 it
is clear that the apparent reduction in medic yield has disturbed the shape of the figure and
is probably due to loss of mature leaf and pod material by the the final han¡est.
Table 3.3.j. yield of oats and medic at various stages of growth when sown at different ratios in the sowing mixture.
transformed data in parenthesis are the means of original data)
Oats or medic
percentage in
the sowing
mixhrre
Yield (kgDNa/ha)
(Days after sowing)
90 r47
25
50
75
100
55 62 118
Oats Medic Oats Medic Oats Medic Oats Medic Oats Medic
3.40(2s) 2.e8(1e) s.3s(zrs) 4.s3(100) 6.se(985) 6.63(7e4) 7.73(2328) 7.06(1172) 8.20(3654) 6.04(436)
4.01(5s) 3.14(4r) s.84(3s0) 4.s4(t44) 7.0s(1157) 6.92(r0s6) 8.01(3188) 7.94(2861) 8.48(4882) 6.80(965)
4.3s(77) 4.20(66) s.sT(3ss) s.s7(267) 1.29(1487) -t.33(rs43) 8.39(4440) 8.10(3298) 8.61(ss40) 7.23(rs0r)
4.s2(s2) 4.s1(e0) 6.23(s2s) 5.97(393) 7.51(1908) 7.18(242r) 8.37(4369) 8.s7(s264) 8.81(6787) 8.08(3301)
LSD 05 0.22 0.28 0.24 0.3s 0.3s
68
Comparison of Total DM Yietd of Oats + Vetch and Oats + Medic Combinatíons:
The DM yield obtained from oa$ plus medic combination was significantly higher than the
DM yield of oats plus vetch combinations 33 days after sowing (Table 3.3.8). There was
no significant difference in DM yield between these species 62 and90 days after sowing.
However, the differences were more obvious 118 and 147 days after sowing. At both the
harvesting stages the oats plus vetch combination produced significantly higher DM yield
than the oats plus medic combination.
Table 3.3.S. Comparison of the total yield oats plus vetch and oats plus
medic combinations sown as pure and mixed stands'
Species Yield (kgDlvf/ha)
(Days after sowing)
62 9033 118 r47
Oats plus vetch
Oats plus medic
82
94
480 2177 6398 7322
480 2270 5384 s4L3
LSD 5 n.s n.s. 822 t674
3.3.3.3.Crude Protein Percentage
The average protein percentage of vetch was significantly higher than the average
protein percentage of oats (Table 3.3.9). The protein percentage of oats was less in the
pure stands compared to the mixed stands of oats plus vetch. However the differences
were not statistically significant. There were significant differences in the protein
percentage of vetch when vetch was so\¡/n as pure or mixed stands with oats. The protein
percentage obtained from plots sown with 25,50 or 75 percent vetch seed in the sowing
mixture was similar. Also there was no signifîcant difference in protein percentage
between plots sown with 50 and 100 percent vetch seed in the sowing mixture.
69
The mean protein percentage of medic was significantly higher than the mean
protein percentage obtained from oats (fable 3.3.10). There \ryas no significant difference
in protein percentage of medic io*n as either pure or mixed stands.
Table 3.3.9. Crude protein percentage of oats and vetch sown at
different ratios.
Oats and vetch soed%oage
in the sowing mixture
Species
Oats Verch
25
50
75
100
6.47
6.6r
7.39
s.39
20.86
22.86
20.73
23.O9
Mean 6.46 21.89
Species
Species x Sowine ratios
***:*
LSD (P=O.05) = 9.37
LSD (P=O.05) = 2.19
Table 3.3.10. Crude protein percentage of oats and medic sown
different ratios.
Oats-medic sæ-dVoage
in ttre sowing mixture
Species
Oats Medic
7.97
6.r7
7.25
7.81
6.72
5.94
5.19
4.73
25
50
75
100
Mean 7.30
Species x Sowine ratios
5.64
,1. {<*
n.s.
Species LSD (P=0.05) = 1.33
70
3.3.4 DISCUSSION
The plant density of oats and vetch followed a similar pattern to that reported in
the previous experiments for these species. Some of variation in the plant density of oats
and medic may be due to the differences in seed numb erlm2 of these species due to the
inaccuracies of machine sowing or caused by or to the presence of hard or dormant seed in
the medic seed lot.
The similar overall mean DM yields of oats and vetch at this particular site agree
with the previous findings of Moreira (19S9a). He concluded that in conditions of soil
nitrogen deficiency inclusion of vetch in the sowing mixture increased the DM production
because soil nitrogen deficiency restricts productivity of oats. The low DM of meÅlc L47
days after sowing may be due to the early-maturing habit of this species (Bowdler and
Lowe 1980) or rhe extremely dry spring may have reduced the potential yield. At this
stage of harvest most plant tissue (leaves, pods) were dried and shattered and were
difficult to collect during sampling. Other investigators (e.g. Litav andZeligman L977)
reported strong competition pressure in favour of oats rather than medic when they
compared Medicago polymorpha and oats grown in mixed culture. Also Arnold et al.
(1935) reported lower percentage of leaves in the lower part of the canopy of lupin grown
mixed with ryegrass because of less light being received.
It is obvious from Table 3.3.8, that an oats plus vetch combination was superior
in DM production than to an oats plus medic combination in the later part of the season
because of the early maturity of snail medic cv. Sava. Thus thoughts must be given to the
selection of vetch tather than snail medic for inclusion in seed mixtures with oats especially
where a mixed hay is desirable. However, in some districts snail medic (also other
legumes) are self-regenerating. Thus oat:medic mixtures are realistic for forage and hay
and could well be cost effective.
The herbage quality of pasture and forage crop species depends on the species
present and their relative stages of growth at harvest (Frame 1985). The protein
percentage of oats, vetch and medic obtained in this study are in close conformity with the
previous workers ( Ahlgren 1956; Smith 1960; Gardner 1961; Radcliffe and Cochrane
71
I
I
I
J
I
I
1970, Launders 1971; Tingle and Dawley 1974;Acikgoz et al.1985). A smalt decrease in
the protein percentage of medic is probably due to plant tissuc like leaves because plant
materials for protein were analysed at last han'est. At the time of last harvest the decline
in dry matter yield of medic reflects the loss of plant tissue due to the early-maturing habit
of this variety.
72
3.4 Experiment 4 The effects of sowing rates and nitrogen
fertilizer on forage . production, grain yietd and quality of
oats-vetch mixtures
3.4.I INTRODUCTION
The results obtained during 1988 from Experiment 3 on the mixed stands of
oats/medic and oats/vetch clearly demonstrated that oats/vetch mixed stands were more
productive than oats/medic mixtures in the later part of the season. Therefore additional
studies in 1989 were designed to further examine oats/vetch mixed stands. The aim of the
present study was to assess the importance of sowing rate and nitrogen fertilizer as factors
affecting the herbage and grain yield and nutritive value of oats/vetch mixtures at
successive stages of growth.
-. The experiment site was located at Urrbrae Agricultural High School, near the V/aite
Agricultural Research Institute. The fîeld had been sown with subterranean clover and
annual ryegrass three years previously but was cultivated fallow prior to sowing of
Experiment 4. Volunteer wild oats (Avena fatua) and soursob (Oxalis pes-caprae) grew
throughout the experiment atea. For detailed information about the site/soil type (see
Section 1,.2 of Table of contents) and climate (rainfall, temperature) is given in the Table
3.1.1.
3.4.2 MATERIALS AND METHODS
Design of Experiment: The experimental design was a randomised complete block
with four replications. There were three sowing rates (D1, D2, D3) of oats (Avena sativa)
cv. Coolabah and vetch (Vícia benghalensis) cv. Popany as follows D1=50 kg seed,/ha,
D2=100 kg seed/ha, D3=200 kg seed/ha. Two nitrogen rates (NO=OkgN/ha, N1=50
kgN/ha) and five sowing fatios of oats to vetch (0:100, 25l75,50:50, 75:25,1ü):0) were
used. Plot size was 1.5 m x 10.0 m comprising 10 rows spaced at 15 cm. Thus there
were a total of 120 plots (Fig. 3.a.1).
73
PLAN OIr EXPERIMIiN't 4
D3 Block I I>2 DI
D2 Block II Dl D3
D3 Block III D2 DI
DI Block IV D3 D2
Figure 3.4.1 showing the plan of the experiment and details of the treatrnents:
Dl = 50kg seeclflra, I)2 = l(X)kg seed/ra, I)3 :200k9 seecl/ha
N = Nitrogen treatnterrt a¡rpliecl to half of the plot.
Sorvingralios: A=oats:vetch=():100,8=oals:vetch=25:75,C=oÍìts:vetclr=-50:50,D =oafs: vctch =75:25,Í:= oats: vetch = l(X):0.
N
1
;N
E
N
DN
A
N
C
N
NBC
N^
N
NED
N^
N
DN
E
N
B
N
¿lN
AN
C
N
D
N
ENN
BA
N
B
N
ENN̂
C
N
D
N
CN
B
N
E
N
tN
B
N
ENN̂
E
N
C
N
;N
BN
D
N
BN
C
N
N̂EN
t,N
AN
C
N
A
N
NBC
N
EN
E
N
(l
N
NB
NDA
N
EN
DN^
N
C
N
BNN
;
74
Fertilizer application: A basal dose of superphosphate at the rate of 110 kÚha was drilled in
all experimental plots and nitrogen fertilizer (urea) at the rate of 50 kgN/ha was drilled in
the nitrogen-treated plots on lst June, 1989.
Sowing details: Sowing rates were based on pure viable seed. This was determined
before the experiment from the mean seed weight, purity and germination percentage of the
seed. Purity and germination of Popany vetch \ryere measured using standa¡d techniques
(Myers 1952) given in the Materials and Methods Section of Experiment 1. while the
information provided with the certified seed of oats were used for the calculations. Seed of
oats and vetch for each plot were weighed and mixed according to the appropriate sowing
ratios. Vetch seed was inoculated with a culture of group "8" Rhízobium immediately
prior to sowing. Seed was sown through a 10-row cone seeder on2 June, 1989 at a depth
of 6-7cm.
3.4.2.1 Data Collection
Plant Establishment Counts: At28 to 29 days after sowing four quadrats each of size
278 mm x 900 mm with long axis across the plots were placed in each plot and plant
density counted.
Harvests: Five harvests (hereafter designated Hl, H2,}J3, H4, H5) were taken
through the season to estimate forage dry matter (DM) production and the sixth harvest
(H6) used to estimate grain yield. Harvests were taken on 20 July (H1), 17 August (H2),
14 September (H3), 11 October (H4), 8 November (H5), 4 December (H6), which were
48,76,104, 131,159 and 185 days after sowing, respectively.
At H1 two quadrats each of size 278 mm x 450 mm and at subsequent ha.rvests two
quadrats each of size278 mm x 900 mm per plot were used to estimate forage yield. At
Hl two quadrats each from each end of the plot and at}Jz two quadrats side by side in
each plot were harvested but there after samples were taken randomly from within the plot.
Samples were shaken free of soil and those from H3, H4 and H5 subsampled. The
samples from Hl and H2 and the subsamples from H3, H4, and H5 were held in a cold-
room at 2-5oC for up to 7 days while awaiting processing. After subsampling, the bulk
¿l
75
sample of harvested material were dried in a forced draught dehydrator at 85oC for
approximately 24 hours and DM yield obtained. The cold-room samples and subsamples
were hand-separated into their respective species before drying except for weeds (Avena
species) which were difficult to distinguish from the sown oats. The dry weight of
subsamples varied from 60 to 300 g with advancing stages of crop growth. The dry
weights of oats and vetch and weeds at the time of H3, H4 and H5 were calculated using
similar procedure mentioned in the Materials and Methods Section of Experiment2.
Number of Tíllers: The tiller number of oats was counted at H5 when the ha¡vested
material was brought to the laboratory. It was difficult to count oats tillers in samples
where oats was only 25 percent of the sowing mixture because of lodging in these plots.
GrainYield: At H6 plants from two quadrats each of size 500 mm x 900 mm per plot
were cut at ground level with a knife. Care was taken to collect all fallen grain or pods of
oats and vetch on the soil surface. The samples were dried at 85oC in a forced draught
oven for approximately 12 hours. Oats and vetch from each plot were threshed and grain
yield calculated.
GrainWeight:: Grain samples from each treatment of oats and vetch were randomly
taken and 100-grain weight obtained.
Plant Nitrogen Analysis: At Hl the whole sample and at H2, H4 and H6,
subsamples from the 0:100, 50:50 and 100:0 sowing ratios for all three sowing rates under
both control and nitrogen-applied treatments were retained for plant nitrogen analysis.
These subsamples were dried at 85oC for approximately 24 hours. For grain protein
estimation, samples were taken from D2 under both control and nitrogen-treated plots at
sowing ratios of 0:100, 50:50, and 100:0. The herbage samples for nitrogen analysis were
ground and passed through a I mm sieve. The samples for grain protein estimation were
ground and passed through a 0.9 mm sieve. In the case of Hl the amount of sample was
insufficient to weigh 1 g for plant nitrogen estimation hence subsamples of 250 mg were
used. In the case of H2, H4 and H6 (herbage protein and grain protein analysis) I g
samples were weighed. These samples were wrapped in a cigarette paper and put in a
.'IIt{
i
I
76
L
r.f
"ì¡
labelled container. The moisture content was measured on approximately 250 mg
subsample of six samples of each species at the time of each harvest. The moisture
percentage was calculated from the data and a corection factor for moisture subsequently
used in calculation of nitrogen and protein concenEation.
Similar procedure for plant nitrogen analysis was followed as mentioned in the
Materials and Methods of Experiment 1. In case of Hl the determination of nitrogen was
based on a colorimetric method using a Technicn auto-analyser methd. For the larger
samples (H2,H4,H6 and grain) an automated distillation and titration apparatus (Tecator
Kjeltec Auto 1030 Analyser) was used for quantitative release of ammonia from digested
samples and titration with 0.1 M hydrochloric acid. Hence percent crude protein was
obtained.
The protein percentage was calculated by multiplying the nitrogen percentage by 6.25
in case of Hl. Protein yield (kg/ha) was calculated by multiplying percent protein by d.y
matter yield (kg/ha) of the respective harvests (i.e. Hl, H2,H4) with one exception. The
protein percentage obtained at the time of H6 was multiplied by the dry matter yield
recorded at the time of H5 as separate dry matter yield of oats and vetch at the time of H6
was not measured because of excessive tangling and leaf fall.
3.4.3 RESULTS
3.4.3.1 Plant Establishment
Species Dffirences: Table 3.4.1 shows the summary of ANOVA for significant
differences between species, sowing ratios, sowing rates, nitrogen and their interaction for
number of plants/m2 and yield (kgDMlha) of oats and vetch when the data was statistically
analysed for species differences.
Oats + Vetch Combined: Table 3.4.2 summarizes the significant differences for
plants/m2 and yield (kgDM/ha) of oats and vetch between sowing ratios, sowing rates,
nitrogen and their interaction when the data was statistically analysed for total number of
plants and yield of oats and vetch at various sowing ratios.
I
I
77
500
400
300
200
100
0
c\¡Éa,É:(d
-ghat)É(l)A
(a)
-¿r--*{l-
5Okg/ha
1 O0kg/ha
200k9/ha
0 25 50 75Percent oat seed in the mixture
100
illtI
500
400
300
200
100
C\ìÉØ
F-9>.at)É(l)a
(b)
-+-ts---#
50kg/ha
1 OOkg/ha
200k9/ha
025 50 75
Percent vetch seed in the mixture100
Figure 3.4.2. Density of (a) oats and (b) vetch at various sowing
rates and sowing mixtures. The corresponding data are presented in
Appendix Table 5.7
0
I
i
I
I
!
78
,'Iä{L ri
"i
There were signif,rcant differences in plant emergence/establishment of oats and vetch
between species, sowing ratios, sowing rates and their interactions (Tables 3.4.1, 3.4.2)
while the use of nitrogen fertilizer had no signifrcant effect on plant establishment.
The mean plant density of oats in pure stands was signif,rcantly higher than the number of
vetch plants in pure stands of vetch (Table 3.4.3). There was no significant difference in
the mean plant density between sowing ratios of 25:75,75:25 and 100:0 of oats and vetch.
Plant density of oats and vetch at sowing ratio of 50:50 was signihcantly lower than the
plant density of oats and vetch at sowing ratios o175:25 and 100:0 while plant density of
oats and vetch at sowing ratios of 50:50 was not statistically different from that of 25:75
and 0:100 oats and vetch sowing ratios. The mean plant density of oats and vetch
increased significantly as sowing rate increased from 50 to 200 kg/ha. Similarly, density
of oats and vetch significantly increased as the seed percentage of these species increased
from 25 to 100 in the sowing mixture at various sowing rates with one exception (Figure
3.4.2 and Appendix Table 5.7). The correlation between observed and expected
establishment gave the following 12 values: oats=O.983; vetch=0.993.
3.4.3.2 Dry Matter Yield
Effects of Sowing Ratios; significant differences were observed in the mean DM yield of
oats and vetch sown as mixtures of 0:1(X), 25:75,50:50, 75'25 and 100:0 throughout the
growing season (Tables 3.4.1,3.4.2 and Appendix Table 5.7). At all stages of maturity,
the DM yield of pure oats or mixed stands of oats and vetch was significantly higher than
the pure stands of vetch except 48 days after sowing when yields of both species in pure
stands and in 50:50 mixed stands had similar yields. The trend in herbage DM yield
obtained from the mixed plots of oats and vetch was not consistent at various stages of
$owth except DM production at a sowing ratio of 75:25 oats and vetch was consistent
throughout the season. Similarly, pure plots of oats produced consistently high DM yield
at all stages of growth. The DM production of the 15.,25 oats, vetch mixture was similar to
the pure stands of oats throughout the season.
II
;
þ
79
Table 3.4.2. Summary of ANOVA of ptant density and yield of oats and
vetch sown at various sowing rates, sowing ratios and nitrogen
treatments. The data of oats and vetch combined were statistically
analysed for plants and DM yietd at various sowing ratios.
Sou¡ce of variation Plants/m2 Yield (kÐM/ha)
(Days after sowing)
48 76 r04 r3l 159
Sowing ratios
Sowing rates
Nitrogen
Sowing ratios xSowing rates
Sowing ratios xNitrogen
Sowing rate xNitrogen
**.d<
**'È
n.s
n. s.
n. s.
n. s.
n. s.
**i( tl.d<*
,l.d< * {<*.*
n.s *** *dr{<
n.s. n.s
n. s. n.s *
n. s. n. s. n. s.
{. {<
n. s. n. s.
*** *{<{.
*** **{< n. S.
** **.
n. s. n.s. n.s.
Sowing ratios x Sowingrates x Nirogen n.s. n.s
{r*
n.s
n. s.
n.s
n.s
l
I
i
i
I
i
80
Table 3.4.1. Summary of ANOVA of plant density yield of oats and vetch
sown at various. sowing rates, sowing ratios and nitrogen
treatments. The data was statistically analysed for species
differences.
Source of variation Plants/m2 Yield (kÐlvl/ha)
(Days after sowing)
48 76 LO4 131 159
Species
Sowing ratios
Sowing rates
Nitrogen
Species x Sowing ratios
Species x Sowing rates
Sowing ratios x
Sowing rates
Species x Nitrogen
Sowing ratios x Nitrogen
Sowing rates x Nitrogen
Species x Sowing ratios xSowing rates
Species x Sowing ratios xNitrogen
Species x Sowingrates x Nifogen
Sowing ratios x Sowingrates x Nirogen
Species x Sowing ratios x
***
***
*.**
n.s
t< {< d<
***
n. s.
n.s.
n.s
*{<*
n.s
n.s
n.s
**,ß
,k**
{<{<*
*d<*
**
**(*
n.s
t(**
n. s.
n. s.
n. s.
d<
*rk{< *** **,È
*** **(* *,ß*
*rk:1. {<t<:* t<rk
*** *** ***
,È l. rl. ,È*rl. ***
n. s. n.s. n.s
n. s. n.s. n.s. n.s
t< {< r< {<,ß* *{<* ***
n.s n.s. n.s n.s.
n.s n.s. n.s. n. s.
***
***
n. s.
**
***
d<
n. s.
*
*
*
x**
n. s. n.s. **
n. s.
n.s. n.s. *
n.s. n.s. n.s.
n. s. n.s. n.s. n.s
Sowing rates x Nitroeen n. s. n.s n. s. n.s. n.s n.s.
81
Table 3.4.3. The effects of different sowing rates and sowing ratios on the
number of plants/m2 of oats plus vetch.
(I-og transformed data: hgures in pa¡enthesis are the means of original data)
Sowing ratios
Oats:Vetch
Sowing rates (kg/ha)
100
Mean
50 200
0:100
25:75
50:50
75:25
100:0
4.87(t32)
5.04(1ss)
s.01(1s0)
s.0s(1s6)
5.1 8(178)
5.34(208)
s.s4(2s4)
s.4s(236)
s.s6(260)
s.48(242)
6.0s(427)
6.06(431)
6.00(403)
6.12(461)
6.rs(482)
s.42(2s6)
s.s5(280)
s.4e(263)
s.s8(292)
s.61(30r)
1 5.47
Sowing ratios
Sowing rates
Sowing ratios x Sowing rates
LSD (P=0.05):0.08
LSD (P=0.05) = 6.66
n.s.
*,k*
***
The DM yield of oats and vetch mixture at 50:50 was similar to that of pure stands of oats
harvested 48,76,104 and 131 days after sowing, while 159 days after sowing it was
significantly lower than the pure stand of oats.
Effects of Sov'ing Rates: The mean DM yield of oats and vetch when sown at
various sowing rates increased significantly as the seed rate increased from 50 to 200
kg/ha in the early part of the season i.e. 48, 76,I04 days after sowing (Appendix Table
5.8). The effects of sowing rates on DM production declined during the season and at 131
days after sowing the herbage DM yield was significantly higher at 100 and 200 kg than
50kg seed rate/ha, while the herbage DM yield at 100 kg was similar to that for a 200
kg/ha sowing rate. There was no significant difference between sowing rates in the mean
herbage DM yield of oats and vetch 159 days after sowing.
82
Generally the DM yield of oats and vetch increased as the ratios of these species
increased from 25 to 100 percent in the sowing mixture at the various sowing rates (Tables
3.4.4,3.4.5, 3.4.6): however, the increase in the DM yield of these species was not
consistently significant.
Table 3.4.4. The effects of sowing rates and sowing ratios on yield of oats
and vetch sown as pure and mixed stands 48 days after sowing.
Species percentage Sowing rates (kg/ha) and yields (kgDlvl/ha)
rn sowlng 50 100 200
mixture Oats Vetch Oats Vetch Oats Verch
25
50
75
100
4364 23
75 4r
111 67
113 106
7t
101
189
172
106 6L
69 181 t20
130 327 209
161 404 285
Species x Sowins ratio s x Sowins rates *** LSD (P=0.05)= 48
83
Table 3.4.5. The effects of sowing rates and sowing ratios on yield of oats
and vetch sown as p.ure and mixed stands 76 days after sowing.
Species p€rcentage Sowing rates (kg/ha) and yields (kgDlvl/ha)
rn sowrng 50 r00 200
rmxtufe Oats Vetch Oats Verch Oats Verch
673
43225
50
75
100
135
503 227
811 3ss
1176 590
524 223
789 370
Lt07
tL75 9r7
690 311
1168 607
1665 1032
1831 1375
Species x Sowing ratios x Sowing rates *** LSD (P=0.05)= 210
Table 3.4.6. The effects of sowing rates and sowing ratios on yield of
oats and vetch sown as pure and mixed stands 159 days after
sowing.
Species percentage Sowing rates (kg/ha) and yields (kgDlvliha)
in sowing
mixture
50
Oats Verch
100
Oats Verch
200
Oats Vetch
25
50
75
100
4980 1675
8s77 3428
10811 4653
12760 879r
3771 2576
7994 454r
10640 6591
13704 9388
4340 2546
6991 4881
10511 7115
13892 7878
Species x Sowing ratios x Sowing rates d< LSD (P=0.05)= 1524
84
Effects of Nitrogen FerÍilizer: There were significant differences in the mean DM
yield of oars 48, 76 anð 104 days after sowing with the application of nitrogen fertilizer
(Table 3.4.7). However, these differences were only significant 48, 76 and 104 days after
sowing. On the other hand mean DM yield of vetch was significantly depressed with the
application of fertilizer 159 days after sowing. The effect of nitrogen fertilizer on the mean
DM yietd of verch was not significant at other stages of growth but there was a Species x
Sowing ratios x Nitrogen interaction 131 days after sowing (Table 3.4.8). Oats grown at
100 percent seed in the sowing mixture produced significantly higher DM yield with the
application of nitrogen fertilizer except 75Vo oats seed in the sowing mixture from nitrogen
treated plots was similar in DM production. Similarly, oats DM yield was significantly
higher in nitrogen treated plots at all sowing ratios with exception that 25Vo oat seed in the
sowing mixture was similar in DM production. There was no significant difference in the
DMyield obtained from vetch at various sowing ratios.
Table 3.4.7. The effects of nitrogen on the mean yield of oats and vetch
so\iln as pure and mixed stands at various sowing rates.
Days after sowing Nitrogen treatments (k/ha) and yields (kgDM/ha)
LSD (P=0.05)0Oas Verch
50Oats Verch
20
86
303
604
622
48
t6
104
131
L4r 109 177 109
819 556 1160 580
2915 2088 4075 1977
6345 403r 7946 3907
159 8094 5662 10068 5015
85
Table 3.4.8. The effects of nitrogen fertilizer on yield of oats and vetch
sown as pure and m.ixed stands at various sowing rates 131 days
after sowing.
Sowing ratios Nitrogen treatments (kg/ha) and yields (kÐlvVha)
0
Oats Verch
50
Oas Vetch
25
50
75
100
Species x Sowing ratios x Nitrogen
3240 2017 3377 1672
5288 3348 7202 3160
7497 4490 10078 5467
9356 6269 rtr26 5329
LSD (P=0.05) = 1208*. {<
There were signihcant differences in the overall mean DM yield of oats plus vetch
sown as pure and mixed stands with and without nitrogen 76,lO4,131 and 159 days after
sowing (Appendix Table 5.9). At all these stages of growth, nitrogen fertilizer
significantly increased the mean DM yield of oats plus vetch. The effects of nitrogen
fertilizer on DM production was not significant 48 days after sowing.
There were also significant interactions between sowing ratios and nitrogen 104
and 131 days after sowing. However, such interactions were not observed at other stages
of growth. The mean DM yield of oats and vetch mixture of 50:50, 75:25 and 100:0
increased signihcantly 104 days after sowing in nirogen treated plots (Table 3.4.9). There
was no significant difference in DM yield between nitrogen treatments when vetch seed
was sown as pure or 75 percent in the sowing mixture.
It is obvious from Table 3.4.10, that at the progressive stage of maturity (i.e. 131
days after sowing) the use of nitrogen fertilizer increased significantly the herbage DM
yield of oats and vetch at sowing ratios of 100:0 and,75;25, whereas the DM yield of
86
0:100, 25:7 5 and 50:50 oats and vetch mixture was statistically similar between control and
nitrogen treated plots.
Tabte 3.4.9. The effects of nitrogen fertilizer on yield (kgDM/ha) of oats
and vetch sown as pure and mixed stands 104 days after sowing.
O-oe transformed data: fisures in parenthesis are the means of original data)
Sowing ratios
Oats:Vetch
Nitrogen treatments (kg/ha) Mean
0 50
0:100
25:75
50:50
75:25
100:0
8.O9(3327)
8.37(4407)
8.29(4049)
8.33(4248)
8.37(4338)
8.06(32s1)
8.52(s076)
8.s4(sl8s)
8.60(s5s6)
8.s3(s143)
8.07(3289)
8.44(2742)
8.41(4617)
8.47(4902)
8.4s(4740)
Mean 8.29ø074\ 8.45(4842\
Sowing ratios
Nitrogen
Sowing ratios x Nitrogen
*** LSD (P=0.05) = 9.16
*rß* LSD (P=0.05) = 6.67
LSD (P=0.05) = 0.15*(
87
Table 3.4.10. The effects of nitrogen fertilizer on yield (kgDM/ha) of oats
and vetch sown as pure and mixed stands 131 days after sowing.
(I-og transformed data: figures in parenthesis are the means of original daø)
Sowing ratios Nitrogen treaÍnents (kg/ha) Mean
Oats:Vetch 0 50
0:100
25:75
50:50
75:25
100:0
8.tt(6269)
e.01(8354)
e.05(8637)
9.r4(9sr4)
e.13(93s6)
8.s4(s32e)
9.06(8844)
9.22(10362)
9.36(117s0)
9.31(11126)
8.63(s79e)
9.04(8499)
9.14(9499)
9.2s(r0632)
9.22(t024t)
Mean 9.0r(8426\ 9.10(.9482\
Sowing ratios *** LSD (P=0.05) = 9.12
Nitrogen ** LSD (P{.05) = 9.93
Sowing ratios x Nitrogen ¡<* LSD (P:0.05) = 9.17
Yield of Weeds: The summary of signifìcant differences in DM yield of weeds
between sowing ratios, sowing rates and nitrogen treatments and their interactions are
given in Table 3.4.11.
There were significant differences in DM yield of weeds in plots of oats and vetch
sown as pure and mixed stands at various stages of growth (Table 3.4.12). The DM yield
of weeds was significantly higher from plots sown as a pure stand of vetch 104, 131 and
159 days after sowing. At other sowing ratios, DM yield of weeds was either similar or
overlapping each other 104, 131 and 159 days after sowing. There was no significant
difference in DM yield of weeds between plots sown with 0:1O0,25:75,50:50 and75:25
oats and vetch sowing ratios 48 days after sowing. Similarly no significant difference in
DM yield of weeds was observed between 100:0, 25:75 and 50:50 oats and vetch sowing
88
ratios while DM yield of weeds in pure plots of oats was significantly lower than the pure
stand of vetch or 75:25 oats and vetch mixture.
Table 3.4.11. Summary of ANOVA on yield of weeds at various stages of
srowth also tillers/m2 of oats
Source of variation
(tillers/m2)
Yield of weeds (kgDlvf¡ha)
(Days after sowing)
76 104 131
Oats
48 159
Sowing ratios
Sowing rates
Nitrogen
Sowing ratios xSowing rates
Sowing ratios xNitrogen
Sowing rate xNitrogen
Sowing ratios x Sowingrates x Nitrogen
n.s. n.s
n.s. n. s.
n.s n.s.
n.s. n. s.
*
n. s.
n. s.
n. s.
n. s.
n. s.
n.s
n.s.
n.s.*
*¡ft,1.
n.s.{<
*,1.*
*:*
n. s.
n. s.
n. s.
n. s.
n. s.
******
n.s.
n.s.
n.s.
n.s.
n.s.
*r.*
******
,l. rk:1.
n.s.
n. s.
n. s.
89
Table 3.4.12. Mean yield of weeds at various stages of growth from plots
of oats and vetch sown as pure and mixed stands.
(I-os transformed data: fisures in parenthesis are the means of original data)
Sowing ratios Yield of weeds (kgDlvf/ha)
(Days after sowing)
104 131Oats:Vetch 48 76 159
0:100 s.62(342) 6.4e(es3) 7.29(1681) 6.9s(re67) s.71(859)
25:75 s.20(2t8) 6.24(6Oe) 6.2s(627) 4.3s(307) 1.38(14)
50:50 s.2e(244) s.ez(s7s) 6.23(6s9) s.s7(382) r.t3(46)
75:25 s.34(286) 6.18(s83) 6.03(576) s.11(333) r.63(34)
100:0 4.86(227) 6.2s(622) s.70(449) s.23(320) 2.24(177)
LSD (P=0.05) 0.46 n.s o.49 0.90 1.15
There was no significant difference in yield of weeds between sowing rates of oats
and vetch sown as pure and mixed stands in the early part of the season (Table 3.4.13).
However the effect of sowing tates \¡/as significant in the later part of the season i.e. 131
and 159 days after sowing. At 131 days after sowing DM yield of weeds was
significantly lower in plots of oats and vetch sown at 200 kg seedlha while there was no
significant difference in yield of weeds between plots sown at 50 or 100kg seed,/ha.
Similarly DM yield of weeds was significantly lower from plots sown at 200kg than 50kg
seed/ha of oats and vetch 159 days after sowing. There was no significant difference in
yield of weeds between 100 and 2ffikg seed/ha.
90
Table 3.4.13. Yield of weeds at different stages of growth from plots of
oats and vetch sown at various rates in pure and mixed stands.
(I-og transformed data: figures in parenthesis are the means of original data)
Sowing rates
(kg/ha)
Days after sowing and yields (kgDlvllha)
76 104 13l48 159
50
200
100
s.t2(247> 6.18(674) 6.4r(797) s.94(962) 3.62(2sO)
s.4s(28S) 6.31(743) 6.32(842) s.s7(s98) 2.33(289)
s.2t(2ss) 6.16(sss) 6.18(7s6) 4.82(426) r.67(139)
LSD (P=0.05) n.s n. s. n.s 0.57 0.89
The mean DM yield of weeds increased with the application of nitrogen fertilizer in
plots sown at various sowing ratios and rates of oats and vetch at various stages of growth
(Table 3.4.14). However, these differences were only statistically significant at 76 and
104 days after sowing.
Table 3.4.L4. The effects of nitrogen fertilizer on yield of weeds
(kgDM/ha) at various stages of growth from plots of oats and
vetch sown as pure and mixed stands.
(I-og transformed data: figures in parenthesis are the means of original data)
Days after sowing Nitrogen treatments (kg/ha)
050
LSD (P=0.05)
48 s.2s(2s8)
6.Oz(st2)
6.14(67 4)
5.33(541)
s.27(269)
6.41(76s)
6.46(923)
s.s6(782)
n.s
0.38
0.31
n. s.
76
104
131
159 2.41(r42\ 2.66(3 10) n. s.
9t
3.4.3.3 Number of Tillers
Table 3.4.11lists the summary of significant differences in the number of tillers/m2
of oats between sowing ratios, sowing rates, nitrogen and the Sowing ratios x Sowing
rates interaction.
Oats tiller number increased significantly as the concentration of oat seed increased
from 25 to 100 percent in the sowing mixture of oats and vetch (Table 3.4.15).
Significantly higher mean numbers of tillers were recorded at 200 kg than 50 or 1(X) kg
sowing rate/ha,while there was no significant difference in oats tiller number/mz between
50 and 100 kg sowing rate/ha.
Table 3.4.15. The effects of different sowing rates on tiller number in oats
grown with vetch as pure and mixed stands.
Sowing ratios Sowing rates (kg/ha) and tillers (#h#) Mean
Oats:Vetch 50 100 200
181
334
256
406
t76
270
409
s09
250249
t74
317
39r
25:75
50:50
75:25
100:0
t94
217
319
Mean 260 283 34r
Sowing ratios
Sowing rates
** {<
**d<
*{<{<
LSD (P=0.05) = 27
LSD (P=0.05) = 23
LSD (P=0.05) = 46Sowing ratios x Sowing rates
It is obvious from the Sowing ratios x Sowing rates interaction (Table 3.4.15) that a
significantly higher number of tillers/m2 was recorded in plots of pure oats, sown at
200kg/ha. The number of tillers was significantly lower from 75 percent oats seed in the
92
sowing mixture sown at 50, 100 and 200kg seed,/ha. The number of tillers increased
significantly as oats seed concentration in the sowing mixture increased from 25 to LOOTo
in the case of all sowing rates except there was no significant difference in the number of
oats tillers between (50:50) and (75:25) or (75:25) and (100:0) oats and vetch sowing
ratios at the 50kg seed/ha. The oat tiller number increased significantly in the pure stands
of oats as the seed rate increased from 50 to 200 kúha. The number of oat tillers/m2 was
significantly higher at oats and vetch sowing ratios of 75:25 when sown at 200kg than 50
or 100kg rate/hawhile there was no significant difference between 50 and 100kg rate/ha at
this sowing ratio. Also no significant difference was observed in the number of tillers
be¡ween 50, 100 or 200kg rate/haat25:75 and 50:50 oats and vetch sowing ratios.
There were significant differences in tillers/m2 of oats between nitrogen treatments
(Table 3.4.16). The mean number of tillers/m2 increased signifîcantly with the application
of nitrogen fertilizer.
Table 3.4.16. The effects of nitrogen fertilizer on tiller number in oats
sown with vetch in pure and mixed stands.
Sowing ratios Nirogen treatrnents (kdha) and tillers (#tr#) Mean
Oats:Vetch 500
181
334
256
406
198
280
368
435
232
25:75
50:50
75:25
lü):0
16s
301
378
Mean
Sowing ratios x Nitrogen
269
,k**
320
n.s.
Sowing ratios
Nitrogen
d<*{< LSD (P:0.05) :27
LSD (P=0.05) = 19
93
3.4.3.4 Herbage Crude Protein Percentage
Data on crude protein percentages for species, sowing ratios, sowing rates and
their interaction at va¡ious stages of growth are summarized in Table 3.4.17 .
The mean crude protein percentage obtained from vetch was signif,rcantly higher
than from oats on days 76, 131 and 185 after sowing (Table 3.4.18 ). In the early part of
the season (i.e. 48 days after sowing), protein percentage from oats was significantly
higher than that from vetch.
There were significant interactions in protein percentage between species and
sowing ratios 131 and 185 days after sowing (Tables 3.4.19,3.4.20). At both stages of
maturity the protein percentage obtained from oats and vetch herbage in pure and mixed
stands followed the same pattern. The protein percentage obtained from pure and mixed
stands of vetch was significantly higher than that obtained from pure or mixed stands of
oats. A significantly higher protein percentage was obtained from pure stands of vetch
than mixed stands of oats and vetch. On the other hand, oats produced significantly lower
protein percentage in pure stands compared to mixed stand with vetch.
94
Table 3.4.17. Summary of ANOVA of oats and vetch crude protein
percentages at various stages of maturity.
Source of variation Herbage crude protein percentage
(Days after sowing)
48 76 131 185
Species
Sowing ratios n. s.
Sowing rates
Nitrogen
Species x Sowing ratios n.s
Species x Sowing rates n. s.
Sowing ratios x Sowing rates n. s.
Species x Nitrogen n. s.
Sowing ratios x Nitrogen n. s.
Sowing rates x Nitrogen n. s.
Species x Sowing ratios x Sowing rates n. s.
Species x Sowing ratios x Nitrogen n.s
Species x Sowing rates x Niuogen n. s.
*
n.s
n. s.
***
n. s.
n.s.
n. s.
n.s.
n.s
n. s.
n.s.
n.s
n.s.
n. s.
n.s.
n. s.
n. s.
n.s
***
*{<
n. s.
***
n. s.
n.s
n.s
n. s.
n.s
n. s.
n.s.
n. s.
n. s.
n.s
,1.**
n. s.
n. s.
n. s.
*d<*
n. s.
n. s.
n. s.
n. s.
n.s
n.s
n. s.
n.s
n. s.
*,È
*
Sowing ratios x Sowing rates xnitrogen
Species x Sowing ratios x Sowingrates x Nitrogen
,Ê
95
Table 3.4.18. Mean crude protein percentages of oats and vetch sown as
pure and mixed stands at various stages of growth.
Days after sowing
(P=0.05)
Species LSD
Oats Verch
48 36.46
t5.44
7.5r
5.51
34.93
24.85
20.27
13.23
1.22
r.22
0.48
0.31
76
131
185
Table 3.4.19. Crude protein percentages of oats and vetch sown as pure
and mixed stands 131 davs after sowing.
Sowing ratios Species Mean
Oats Verch
Pure stand (I00Vo) 6.43
8.58
20.65
19.89
13.54
14.24Mixed stand
Mean 7.5t 20.27
Species
Sowing ratios
***
*r<
:ft t< d<
LSD (P=0.05) = 6.43
LSD (P=0.05) = 9.43
LSD (P=0.05) = 9.63Species x Sowing ratios
96
Table 3.4.20. Crude protein percentages of oats and vetch sown as pure
and mixed stands 185 days after sowing.
Sowing ratios Species Mean
Oats Vetch
Pure stand (l00%o)
Mixed stands (50:50)
4.93
6.09
t3.73
12.74
9.33
9.41
Mean 5.51 13.23
Species
Sowing ratios
*{.*
n.s
**rk
LSD (P=0.05) = 9.37
LSD (P=0.05) = 9.53
,'lru
';Species x Sowing ratios
II
lI
Table 3.4.2', describes significant differences in protein percentage between
sowing rates at various stages of maturity. The percentage protein obøined from oats and
vetch sown as pure and mixed stands at rates of 50kgiha was signif,rcantly higher than for a
200kg ratelha.43 days after sowing. There was no significant difference in protein
percentage of oats and vetch between sowing rates of (50 & 100) and (100 & 200) kg
seed/ha. Similarly, the protein percentage of oats and vetch at sowing rates of 50kg was
significantly higher than 100 kg seed/ha 131 days after sowing. The mean protein
percentages of oats and vetch between sowing rates of (50 & 200) or (100 & 200) kg/ha
were similar: at other stages of maturity there was no significant differences in the protein
percentâges for different sowing rates.
!
I
97
Table 3.4.2L. The effects of different sowing rates on mean crude protein
percentage of oats and vetch at various stages of growth.
Sowing rates (kg/ha) I-SDDays after sowing
(P=0.05)
50 100 200
48 36.79 35.40 34.90 1.50
76 19.85 20.02 20.55 n.s.
131 14.33 13.51 13.83 0.59
185 9.57 9.38 9.r7 n.s
Nitrogen fertilizer increased mean protein percentage of oats and vetch sown as
pure stands and in mixtures 48 days after sowing (Table 3.4.22). However, nitrogen has
no effect on protein percentage at other stages of growth.
Table 3.4.22. The effects of nitrogen fertilizer on the mean crude protein
percentage of oats and vetch at various stages of harvest.
Days after sowing Nitrogen treatments (kglha) LSD (P=0.05)
ilr;j
500
48 35.0s 36.34 1.22
76 20.32 19.96 n. s.
131 13.92 13.85 n. s.
185 9.25 9.49 n. s.
There was also a significant interaction between Sowing ratios x Sowing rates x
Nitrogen for the percent protein of oats and vetch observed 185 days after sowing (Table
3.4.23). The differences in protein percentage between nitrogen treatments and sowing
rates were not consistent. The protein percentage obtained from mixed plots, with nitrogen
I
I
_t _ __--r{=
Table 3.4.23. The effects of sowing rates and nitrogen fertilizer on crude protein percentages of oats and vetch
sown as pure and mixed stands 185 days after sowing.
Sowing ratios
50
Nitrogen treatments (kg/ha)
050
Sowing rates (kg/ha)
100
Nitrogen treatments (kg/ha)
0s0
9.45 8.66
9.11 r0.22
9.31 9.44
200
Nitrogen treatments (kg/ha)
0s0
Pure stand (l00Vo) 9.s9
Mixed stand (50:50) tì.99
Mean 9.29
Sowing ratios
Sowing rates
9.93
9.19
9.86
8.91
9.39
9.r5
9.45
8.92
9.18
Mean
9.33
9.41
n.s
n. s.
ratios x Sowi rates x Ni LSD 5 = 0.91
\ooo
99
jli
i
and 100kg/ha sowing rare, was significantly higher than from a mixed stands of oats and
vetch at 50kg and 100kg sowing rute/ha without nitrogen and also from pure stands
without nitrogen at 200kg sowing ratelha. Similarly, the protein percentage in this
treatment was significantly higher than the nitrogen-treated pure stands at 100kg sowing
ratelhaand also from nitrogen-treated mixed stands at 200kg sowing ratelha. This table
will not be discussed further because the interactions between these treatments was small
and there was no such interaction at other stages of growth.
3.4.3.5 Herbage Crude Protein Yield
It is obvious from the summary of ANOVA that there were significant differences
in herbage crude protein yield of oats and vetch between sowing ratios, sowing rates,
nitrogen and interaction between sowing ratios and sowing rates also sowing ratios and
nitrogen at various stages of growth (Table 3.4.24).
Table 3.4.24. Summary of ANOVA for crude protein yield of oats and
vetch when sown as pure and mixed stands.
Source of variation Herbage crude protein yield (kg/ha)(Days after sowing)
48 76 131 185
Sowing ratios n. s.
Sowing rates ***
Nitrogen n.s
Sowing ratios x Sowing rates n.s
Sowing ratios x Nitrogen n.s
Sowing rates x Nitrogen n. s.
n. s.
***
*x*
n. s.
n. s.
***
n. s.
n. s.
n.s
***
n. s.
n.s.
n.s.
n.s
n.s
rF
{<
*<
I
Sowing ratios x Sowingrates x Nitrogen
!
n. s. n. s. n. s. n. s.
100
There was no significant difference in protein yield between pure and mixed
stands of oats and vetch up to 76 days after sowing (Figure 3.4.3 and Appendix Table
5.11). Pure stands of vetch and mixed stands of oats and vetch produced significantly
higher protein than pure stand of oats, while pure stands of vetch and mixed stands of oats
and vetch were similar in protein yield at this stage of maturity. Harvesting at a late stage
of maturity (185 days after sowing) resulted in significantly higher protein yields in pure
stands of vetch than either mixed stands of oats and verch or pure stands of oats.
In the early part of the season (i.e. 48 and76 days after sowing), the mean protein
yield increased significantly with an increase in the sowing rate from 50 to 200 kg/ha
(Figure 3.4.4). The trend in protein production changed 131 and 185 days after sowing.
The higher sowing rate (200 kdha) was significantly higher in protein yield than the
lowest sowing rate (50kg/ha) 131 days after sowing, while the medium sowing rate (100
kg/ha) at this stage of maturity was similar in protein yield to both of the sowing rates (i.e.
50 and 200 kg sowing ratelha). There was no significant difference in the mean protein
yield of oats and vetch at various sowing rates 185 days after sowing.
Table 3.4.25, demonstrates the interaction between sowing ratios and sowing
rates 76 days after sowing. The protein yield obtained from pure and mixed stands of oats
and vetch increased significantly as sowing rate increased from 50 to 200 kglha except
similar protein was obtained from oats and vetch sowing ratios of 100:0 and 50:50 at
sowing rates of (50 & 100) and (100 & 200) kg/ha respectively. The protein yield
obtained from pure stands of vetch did not differ from treatments sown at the 50 and
lOOkg/rate. There were significant differences in protein yield of pure and mixed stands of
oats and vetch at200 kg seed,/ha. A significantly higher protein yield was obtained from
pure stands of vetch than from the mixed stands of oats and vetch. At this sowing rate
there was no significant difference in protein yield between sowing ratios of oats and vetch
(0:100 & 1ü):0) and (50:50 & 100:0).
WAFc l,!ti01¡iJï.Ë
tER¡nY
cg
bvÉ(l)
ot<Þc)€É()
(Ho€c)
6U)
500
400
300
200
r00
6(x)
su)
4(X)
300
2fi)
r(x)
O¡tts-Vetc:h
{- o-1oo
-t]- 50_50
--i\- 1oo-o
048 76 l3l 1tì5
Days alter sowing
Figure 3.4.3 Crude protein yietd of oats plus vetch s_own as pure andmfxed stands at varioul stages- of growth. The statistical analysis wasperformed on log transformed data. - The corresponding data is presentedin Appendix Table 5.11.
(d
bJ¿
0.)
o¡rÈc)
5L(-)i+{
t6)
04ll 7(t I 3l I tl5
Dltys after sorving
Figure 3.4.4 The effects of sowing rates on !!e crude protein yiel.dof"oats plus vetch at various stages oi growth. The statistical analysiswas per-formed on log transformed data. The corresponding data ispresented in Appendix Table 5.12.
¡I
toz
Table 3.4.25. The effects of different sowing ratios and sowing rates on
crude protein yield from oats and vetch 76 days after sowing.
(I¡ transformed data: figures in oa¡enthesis are the means of orisinal data)
Sowing fatios Sowing rates (kg/ha) and crude protein (kg/ha) Mean
Oats:Vetch 50 100 2m
0:100
50:50
100:0
4.27(73.4) 4.63(111.7) s.L4(17s.4) 4.70(120.1)
4.28(73.s) 4.67(rI1.D s.L3(r7O.2) 4.69(118.2)
4.4s(s1.4) 4.44(eO.4) 4.87(r37.7) 4.6O(106.s)
Mean 4.3s09.4) 4.60(104.4\ 5.05(161.1)
Sowing ratios n. s.
Sowing rates LSD (P=0.05) = 9.16
Sowing ratios x Sowing rates LSD (P{.05\ = 0.27
The effect of nitrogen fertilizer on the mean protein yield of oats and vetch sown
as pure and mixed stands is shown in Table 3.4.26. The protein yield increased with the
applicaúon of nitrogen fertilizer at all stages of maturity. However, these differences were
statistically significant only at 76 days after sowing.
Table 3.4.26. The effects of nitrogen fertilizer on total crude protein yield
of oats and vetch at various stages of growth.
(I-og transformed data: figures in parenthesis are the means of original data)
{<{<*
*
Nitogen treatments Days after sowing and crude protein (kdha)
(k/ha)
48 76 131 185
0
50
2.63(r6.1) 4.s6(104.0) 6.14(502.0) 6.0e(467.0)
2.7s(1s.3) 4.17(rzs.9) 6.17(505.0) 6.17(49s.O)
LSD (P= 0.0s) n. s. 0.13 n. s. n.s.
103
The interaction between sowing ratios and nitrogen presented in Table 3.4.27
shows that no significant difference was observed in protein yield between pure vetch, or
oats and vetch mixed stands, grown in control plots or 50 kgN/ha applied. The protein
yield from the pure oats stand was significantly lower than the pure stand of vetch or oats
and vetch mixed stands from both control and nitrogen-treated plots. There was no
significant difference in the mean protein yield of oats and vetch when sown at various
sowing ratios. These interactions (Sowing ratios x Sowing rates, Sowing ratios x
Nitrogen) will not be considered in the subsequent discussion, since they were consistently
small and, with few exceptions, statistically non-signihcant.
Table 3.4.27. The effects of different sowing ratios and nitrogen fertilizer
on crude protein yietd (kg/ha) of oats and vetch 131 days after
sowing.
transformed data: figures in parenthesis are the means of original data)
Sowing ratios Nirogen treaünents (kg/ha)
100
Mean
Oats:Vetch 0
0:100
50:50
100:0
6.44(6s2.0)
6.30(5s7.0)
s.68(2e7.0)
6.24(s36.0)
6.40(615.0)
s.88(364.0)
6.34(s94.O)
6.3s(s86.0)
s.78(330.0)
Mean 6.14(502.0) 6.17(sOs.0)
Sowing ratios
Nitrogen
*{<*
n. s.
LSD (P=0.05) -- 0.14
LSD æ=0.05) = 0.20Sowins ratios x Nitroeen *
3.4.3.6 Grain Yield
There were significant differences in the mean grain yield of oats and vetch between
various sowing ratios, sowing rates and nitrogen fertilizer treatments. Also significant
104
differences were observed between species and interactions between species and sowing
rates and species, sowing ratios and nitrogen (Table 3-4.28).
The mean grain yield of oats and vetch increased significantly as the percentage of
oats in the sowing mixture increased from 25 to 100 percent in the sowing mixture (Iable
3.4.29). The mean grain yietd of oats and vetch sown at various sowing rates was
significantly lower at 50kg than 100kg and 200kg sowing rates/Ïa, while there was no
signif,rcant difference in the mean grain yield of oats and vetch at the 100 and 200 kg
sowing rate/ht.
Table 3.4.28. Summary of ANOVA of grain yield and grain crude protein
percentage of oats and vetch.
Source of variation Grain yielda Grain Grain weight Grain crude
(ø100) protein(%o)(ke/ha) fts/ha)
Species
Sowing ratios
Sowing rates
Nitrogen
Species x Sowing ratios
Species x Sowing rates
Sowing ratios x Sowing rates
Species x Nitrogen
Sowing ratios x Nitrogen
Sowing rate x Nitrogen
Species x Sowing ratios xSowing rates
Species x Sowing ratios xNitrogen
Species x Sowing rates xNitrogen
Sowing ratios x Sowingrates x Nitrogen
Species x Sowing ratios xSowing rates x Nitrogen
*
*
***
n. s.
****¡ft:*
,ß
*{<**
*
n. s.
,lr{. *
n. s.
n.s.
n.s.
n. s.
n.s.
n.s
:ßì.*
,F {<
n. s.
n. s.
**,È
n. s.
n. s.
n. s.
n. s.
n.s.
*t<*
***
n.s**
n.s.
n. s.
n. s.
*
**
n. s.
n. s.
n. s.
n.s
n. s.
n.s.
plus vetch was statistically analysed ata. Represents when mean grain yield of oatsyield of oats plus vetch was statistically
105
Table 3.4.29. The effects of different sowing ratios and sowing rates on
grain yield of oats and vetch.
Sowing ratios Sowing rates (kg/ha) and grain yield (kg/ha) Mean
Oats:Verch r00 20050
0:100
25:75
50:50
75:25
100:0
1020
t693
2839
3902
4323
1001
1209
3111
4803
5240
1097
1679
32t3
456/'
5349
1039
1527
3054
4423
4971
Mean 2755 3073 3180
Sowing ratios
Sowing rates *
*{.d<
n. s.
LSD (P{.05) = 375
LSD (P{.O5) = 291
Sowing ratios x Sowing rates
The application of nitrogen fertilizer increased grain yield of oats at 50 and 75 percent
oar seed in the sowing mixture (Table 3.4.30). The increase in grain yield at 25 and 100
percent oats seed in the sowing mixture was not statistically significant. The grain yield of
oats increased significantly as oat seed increased from 25 to 100 in the sowing mixture in
both conrol and nitrogen treatments. There was no significant difference in grain yield of
vetch when vetch seed was 50, 75 or 100 percent in the sowing mixture both in control
and nitrogen-treated plots. Similarly, there was no significant difference in vetch grain
yield between (25,50, 75) and (25, 50) percent vetch seed in the sowing mixture in both
control and nitrogen treated plots respectively.
106
Tabte 3.4.30. The effects of nitrogen fertilizer on grain yietd (kg/ha) of
oats and vetch sown at various sowing ratios.
Oat seed in the
sowing mixture
(Vo)
Nirogen trearnents (kg/ha) Mean
500
63472225
50
75
100
547
1792
3431
495r
2781
MM
4990
2286
3938
497t
Mean 2680 3234
Vetch seed in the
sowing mixture
(vo)
48s
893
768
1039
3s6
602
850
r02t
934
615
935
1057
25
50
75
100
Mean 88s 707
Species x Sowing ratios
Nirogen
*** LSD (P=0.05) = 293
LSD (P{.5) = 149
LSD (P=0.05) = 421
,k
Species x Sowing ratios x Nitrogen *'ß
3.4.3.7 Grain Weight
The summary of ANOVA for significant differences of 100-grain weight between
species, sowing ratios, sowing rates, nitrogen and their interactions is given in Table
107
3.4.28 when the data was statistically analysed for species differences. Table 3-4.3L
shows that mean 100-grain weight of vetch was significantly higher than the mean l0O
grain weight of oats. There *ui no significant difference in the mean 100-grain weight of
vetch sown at various sowing ratios with oats in the sowing mixture. On the other hand
100-grain weight of oats was significantly higher when oats seed was 100 percent in the
sowing mixture. There was no significant difference in the 100-grain weight of oats sown
at a sowing rate of 50 or 75 percent in the sowing mixture. The 100-gfain weight of oats
sown as 25 percent seed in the sowing mixture was significantly 1o\4'er.
Table 3.4.31. Mean grain weight of oats and vetch sown as pure and
mixed stands at various sowing rates.
Sowing ratios Species and 100 grain weight (g)
Oats Vetch
4.s3
4.51
4.49
4.39
2.81
3.00
2.96
3.29
25
50
75
100
Mean 3.02 4.48
Species *** LSD (P{.05) = 6.67
LSD lP=0.05) = 0.14Species x Sowins ratios ***
3.4.3.8 Grain Crude Protein Percentage
Significant differences in grain crude protein percentage of oats and vetch were
observed between species and sowing ratios. The interactions of species and sowing
ratios also species and nitrogen were significant (Table 3.4.28).
108
The mean grain crude protein percentage of vetch was significantly higher than
oats (Table 3.4.32). Similarly mean grain crude protein percentage was significantly
higher in mixed stands of oats and vetch than in pure stands of oats.
Tabte 3.4.32. Grain crude protein percentages of oats and vetch sown as
pure and mixed stands.
Sowing ratios Species Mean
Oats Vetch
Pure stand (l007o)
Mixed stands (50:50)
10.90
t2.76
28.05
28.33
19.48
20.55
Mean 11.83 28.r9
Species
Sowing ratios
:l.rßX
*,F*
*:k
LSD (P=0.05) = 9.56
LSD (P=0.05) = 9.56
LSD (P=0.05) = 0.70Species x Sowins ratios
The interaction between species x sowing ratios (Table 3.4.32) shows that a
significantly higher protein percentage was obtained from vetch seed sown as pure or
mixed stands than the pure or mixed stands of oat seed. There was no significant
difference in grain protein percentage of vetch when sown as pure or mixed stands. On the
other hand, significantly higher oats grain protein percentage was obtained from mixed
stand of oats than from the pure stand of oats. There was no signihcant difference in the
mean crude protein percentage of oats or vetch sown as pure or mixed stands due to
nitrogen fertilizer application (Table 3.4.33).
109
Table 3.4.33. The effects of nitrogen fertilizer on percent grain protein of
oats and vetch.
Species Nitnogen treaünents (kglha) Mean
0 50
Oatst
Vetcht
r 1.55
28 00
t2.ll
28.39
11.83
28.19
Mean 19.77 20.25
Species
Nitrogen
***
n. s.
n. s.
LSD (P=0.05) = g.5g
Species x NitrogenT Mean derived from pure stands and mixture.
3.4.4 DISCUSSION
Differences in plant density between oats and vetch were due to the differences in
seed size between the two species. The plant density of oats and vetch in mixtures was
equivalent to their expected plant population i.e mixing the species did not interfere with
establishment. The differences in plant populations could have resulted in the differences
in early DM production observed in the various treaünents as at this time there would have
been relatively little inter-plant competition.
The pure stand of oats produced signifîcantly higher average DM yield than the pure
stand of vetch throughout the growing season except 48 days after sowing. This
difference in herbage DM yield of both the species may be due to species differences in
gowth rate. Generally legumes produce less DM yield than glasses in most favourable
conditions (Moreira 1989).
The consistently-higher DM yield of oats sown alone was similar or higher than
those obtained from the comparable oats and vetch mixtures, suggesting that oats was the
r10
high-yielding component of the mixture at this site. Harper (1977) cited from van den
Bergh's (1953) stated that when two species of glasses were grown in mixtures, total yield
was similar to that of the highêr yielding pure stands. Donald (1963) concluded, from
reviewing earlier literature, that there \rras no advantage in sowing a mixture of grass
species to maximize DM production under ideal and constant conditions. However
Snaydon (1976) cited by (Harper 1977) pointed out that in uncertain conditions the mixture
will give on average higher yields than a pure stand. On the other hand many workers
(frenbath 1974;Willey 1979;Rao and Willey 1980; Osman and Osman 1982; Osman and
Nersoyan 1986) have reported maximum yield from mixed population of species rather
from pure stands. They attributed the yield advantage from mixed cropping to the degree
of complementarity between the component crops of a mixture.
The results reported by Osman and Nersoyan (1986) from experiments ca¡ried out
on cereal and legume mixed cropping in a Mediterranean type of climate contradicts our
results. Osman and Nersoyan (1986) found increased yield with the increase in the
proportion of legumes when they compared cereals (triticale, oats, barley) and legumes
(peas, vetches) at various sowing ratios. However they conducted their study in a f,reld
with low organic matter (IVo), with an annual rainfall of 32O mm; and without fertilizer
nifogen. In comparison our experimental site had been under a pasture of subterranean
clover and ryegrass for three years prior to the experiment, which would have increased
the fertility of soil. Furthermore, in our experiment nitrogen Eeatnents of 50 kgN/ha were
used.
The results under discussion comparing the average DM yield of various sowing
ratios of oats and vetch are based on the mean value obtained from conüol and nitrogen
treafinents. In another study on oats-vetch mixtures calried out in the Meditenanean-type
environment, Moreira (1939) concluded that the increased use of vetch seed in the sowing
mixture increased herbage DM yield where available soil nitrogen was low, and
consequently where the oat crop was not very productive. On the other hand, under the
most favourable conditions DM production was greater from oats than vetch.
111
In our 1989 studies the increase in winter forage yield with increase in sowing rates
of oats and vetch agree with the previous findings of Crofts (1966b); Robinson and Sykes
(1973). Similarly, the increased in the mean herbage DM production with the application
of nitrogen fertilizer in our study confirms the previous findings of several workers (Crofts
1966a;1966b; Brown 1975l' Lowe et al. l98O; Moreira 1989). Lowe et al. (198O) found
significant response of oats to nitnogen fertilizer under both irrigated and rainfed conditions
on extremely fertile soils. On the other hand nitrogen fertilizer depressed vetch DM yield
(Kamprath et at. 1958;'Wassermann et al.1984). In our study the reported yield is the
overall mean herbage DM yield of oats and verch.
The experimental site was infested by weeds mainly soursob and wild oats. In the
early part of the season (48 days after sowing) samptes were taken from the ends of the
plots, the variable emergence and more weeds may have contributed to the higher DM yield
of weeds at this stage of harvest. The increased in yield of weeds in the pure stands of
vetch by comparison to the oats and vetch mixture or pure stand of oats 104, 131 and 159
days after sowing was most probably because of the presence of wild oats on the
experimental site. At the time of separation of sown species and weeds the weed
component in case of pure vetch plots consisted of wild oats while in case of oats and
vetch mixed plots it was not possible to recognize wild oats and separate them from the
sown oats. The significant effects of high sowing rates in the later part of the season on
DM yield of weeds agree with the previous findings of (Bteasdale 1960; Ervio 1972).
These workers has reported depressed DM yield of weeds with an increase in the sowing
rates of crops. The response of weeds to nitrogen fertilizer in the early stages of growth
support the previous findings of Gill and Blacklow (1984); Smith and Levick (L97Ði'
Forcella (1934). Gill and Blacklow (1984) reported early competition for nutrients by
weeds in wheat.
The higher number of tillers at high sowing rates support the previous findings of
Kirby (1967). The increase in the number of tillers with the application of nitrogen
fertilizer has been previously reported by many workers (e.g. Needham and Boyd 1976;
tt2
Gralram et at.1983; Garcia del Moral et at.1984). They have reported increased number
of tillers, stem elongation and herbage yield in cereal crops with the early application of
nitrogen fertilizer.
The higher grain yield of oats than vetch agree with the previous reported grain yield
of oats by Hansen (1988) and for vetch by Covarelli (1974) and Antsiferov (1975). The
increase in grain yield of oats and vetch at various sowing rates are comparable with the
resultsof Marshalletal.(1987). Theycomparedsowingrates of 67,101 and l34kglha
of oats and found maximum yield from l01kg ratelha. The reason for an increase in grain
yield of oats and a decrease in grain yield of vetch with the application of nitrogen fertilizer
may be that nitrogen fertilizer increased growth of weeds and allowed benefit to oats in
nitrogen-treated plots to compete better with vetch comparatively to oats in control plots at
similar sowing ratios. This phenomenon is evident in this study from Table 3.4.30 and
has been reported by several workers (e.g. Kamprath et al. 1958: Wassermann et a\.1984;
Jepsen 1986 and Dovydaitis 1988) in grass-legume mixtures.
Generally, forage quality is strongly dependent on protein level. Thus the practical
exploitation of forage crops involves a compromise between yield and quality. The higher
protein percentages of oats and vetch in the early part of the season and a decline with the
progressive stage of maturity support the previous findings of several workers (e.g.
Klebesadel 1969; Burgess et at.1972). Klebesadel (1969) reported that percent protein in
oats decreased rapidly from the 6-leaf stage to late anthesis. Thereafter percent protein
declined very slowly reaching 8 percent 115 days after sowing. In comparison percent
protein in peas declined more slowly than in oats during the sampling intervals. A similar
trend of declining percent protein of oats and vetch was recorded in this study (Figure
3.4.S). Klebesadel (1969) also reported higher percent protein in oats than peas 36 and M
days after sowing. Our results showing higher percent protein in oats than vetch 48 days
after sowing are in agteement with Klebesadel's results. The probable reason for higher
protein in oats than vetch may be that oats seedlings consists of leaves while generally
leaves have higher protein than stem. In the case of vetch or peas, plants at this stage
consist of stem and leaves which may affect the proportion of leaves in these plants
113
compared to oats. At the stage of maturity (approximately 131 days after sowing) when
the oats and vetch mixture was harvested a wide disparity in percent protein existed
between the two species (Figure 3.4.S). This higher protein content of vetch herbage
shows the importance of vetch mixed with oats for nutritious forage production or for
fodder conservation.
The decrease in protein percentage in pure stands of oats below that of the mixed
stands of oats in the oats/vetch mixture 131 and 185 days after sowing may be due to the
lesser number of plants/m2 of oats in the mixed plots than the number of oats plants in the
pure stand. The lower in protein percentage for vetch plants in mixed versus pure stands
may be due to the loss of leaves which may have occurred during the process of species
separation. Another reason may be the complex factors controlling the growth of cereal
and legumes in the mixture may have encouraged the growth of oats. This may have
caused reduced growth and vigour of vetch by competition and smothering by the
generally taller growing oats plants.
Although the low sowing rate (50kglha) led to higher mean protein percentages of
oats and vetch at some stages of maturity the overall trend in herbage percent protein was
not consistent. Moreira (1989) reported that there was no significant effect on protein
percentage of oats and vetch at various sowing rates. The effect of nitrogen fertilizer
significantly affected the mean percent herbage protein in the early stage of growth.
However, it had no effect in the later part of the season. The protein percentage reported
here is the mean of oats and vetch at various sowing ratios.
The mean grain crude protein percentage of oats was significantly higher in the
mixed stands of oats than in the pure stands of oats while there was no significant
difference in the crude protein percentage of vetch between plots sown as pure stands or
mixed with oats. In contrast Anderson (1975) reported higher protein concentration in
vetch grown alone than grown with oats. The application of nitrogen fertilizer did not
increase the mean grain crude protein of either oats or vetch.
3.5 Experiment. 5: The effects of nitrogen fertilizer on
forage and grain yietd of different oat cultivars and
vetch species in pure stands and mixtures
3.5.1 INTRODUCTION
Following the 1988 studies on oat:vetch and oat:medic mixtures, this
experiment was established in 1989: it involved all combinations of a semidwarf and a
tall oat cultivar and two vetch species in pure stands or 50:50 mixture. The objective of
the experiment was to show the impact of nitrogen fertilizer and plant height on dry
matter and grain yield of oats and vetch. Also the effects of oats and vetch in pure stands
and mixtures on soil total mineral nitrogen and moisture contents were studied during the
season.
3.5.2 MATERIALS AND METHODS
Design of Experiment: and Sowing Details: The experimental design was a
randomised complete block with a factorial treatment structure with four replications.
There were two cultivars of oats (Avena sativa) cvs. Coolabah and Dolphin and two
vetch species (Viciabenglnlensis) cv. Popany and(Viciavillosa subspp. dasycarpa) cv.
Namoi, three sowing ratios of oats:vetch (0:100, 50:50 and 100:0) and two nitrogen
rates (NO=OkgN/ha, N1=50 kgN/ha). Plot size was 1.5 m x 10.0 m with row spacing
of 15 cm.
The information about experimental site, seedbed preparation, methods of
sowing and fertilizer application are given in the Materials and Methods section of
Experiment 4. The adjustment of the d¡ill setting for sowing depth was at 5-6 cm.
There was a total of 96 plots. Figure 3.5.1 shows the layout of the Experiment.
I
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116
3.5.2.1 Data Collection
Plant Estabtishnent: After emergence of sown species four galwanized wi¡e
quadrats 278 mmx 900 mm were placed in each plot across the line of rows to sample 6
rows. The number of oat and vetch seedlings were counted 3l days after sowing.
Yield: To estimate forage dry matter (DM) production and grain yield five
harvests were taken throughout the growing season. These harvests were on 27 luly
(Hl),z4August (H2\,28 September (H3), 25 October (H4) and ll December (H5)'
which were 55, 83, 118, 145 and 193 days after sowing respectively. At the last harvest
(II5) g¡ain yield was estimated rather than herbage DM yield. At Hl two quadrats each
of size 278 mmx 450 mm were used and at subsequent harvests DM production was
estimated from two quadrats each of size278 rnm x 900 mm per plot. Plants within the
quadrats \¡/ere cut at ground level with a knife and the two samples from each plot were
bulked. At Hl two quadmts one from each end of the ploS were harvested but thereafter
samples were taken randomly within the plos. The same procedure used for Experiment
4 was followed for further processing of these samples.
Plant Height:The height of oat cultivars and vetch species both in pure and
mixed stands was measured on 23 October i.e.143 days after sowing: plant height was
measured from the ground level to the top of the canopy at 10 different spots in each
plot. In the mixtures plant height of oats and vetch at each sampling point were recorded
separately.
Number of Tillers: At H4 the number of tillers \¡/as counted on each of the
samples of oats in pure stands and mixed stands.
Grain Yietd: At H5, two quadrats were harvested for estimating grain yield.
Any oat grain or vetch pods on the soil surface were collected and put in bags with the
harvested material: these bags was dried at 85oC in a forced draught oven for
approximate\y 12 hours. Oats and vetch from each plot were threshed, the grain
117
weighed and grain yield calculated.
Grain Weight: Random grain samples were taken from each treatment to
determine 100-grain weight and 100 grain weight.
Soil Moisture.' Gravimetric water content of the soil was estimated during the
season in plots of pure Coolabah oats, pure Dolphin oats, pure Popany vetch and pure
Namoi vetch, and from CoolabahÆopany and DolphinÂ.[amoi mixtures. Only plots
receiving no nitrogen were sampled. One soil sample each at depths of 0-30 and 30-60
cm from each plot was taken with Jarret auger of diameter of about 82mm on 17
October, 30 October, 22 November and 17 December, which were L37,150, 173 and
198 days after sowing respectively. Representative soil sub-samples were sealed in tins,
weighed, oven-dried in open tins at 105oC for approximately 24 hours, reweighed and
the moisture contents calculated as a percentage of the weight of the oven dried soil using
the following formula
Percent soil moisture = Wet soil weight - Dry soil weight x 100
Dry soil weight
SoilTotal Mineral Nitrogeni To estimate soil total mineral nitrogen, (ammonium
plus nitrate plus nitrite), soil samples were taken on 6 July (S1), ll August (S2)' 11
September (S3), 8 October (S4), and 16 December (S5) 34,70,101, 128 and 197 days
after sowing respectively.from plots that received no nitrogen fertilizer. Four soil
samples (82 mm diameter x 0-15cm and 15-30cm depth) per plot were taken with a soil
auger at 51 and three soil samples (same dimensions) taken on subsequent sampling
occasions. The soil samples were taken from each plot of pure Coolabah oats, pure
Popany vetch and 50:50 mixture of Coolabah oats and Popany vetch. The soil samples
were dried at 40oC for about 24 hours ground and passed through a 2 mm sieve.
Samples (20 g) were extracted with 100 mt 2M KCL and kept at2-5rc until required for
analysis. Total soil nitrogen was determined by the steam distillation method (Bremner
1965; Keeney and Nelson 1982). The mineral nitrogen concentration (ppm) was
calculated on the basis of (nitrate + ammonia + nitrite).
118
3.5.3 RESULTS
Two analysis were conducted on the data: the oat and vetch data were combined to
examine the effects of sowing ratios and nitrogen on the crops and data was re-analysed
with the oats and vetch data kept separate to examine the influence of species and
cultivars on growth and yield.
3.5.3.1 Plant Establishment and Yield
Species effects separately and. combíned:Table 3.5.1 summa¡izes the ANOVA
for plant density and yield data when the data was analysed statistically for cultivars and
species differences, while Table 3.5.2 summarizes the differences in plant density and
yields of oats and vetch when the data was statistically analysed for total number of
plants of oats plus vetch at various sowing ratios.
The number of oat plants was significantly greater than the number of vetch
plants in both pure and mixed stands (Tables 3.5.1 and 3.5.3). There was no significant
difference in the number of plants within oat cultivars or within vetch species. The total
number of plants (i.e. oats + vetch) was significantly higher in pure stands of oats and
oars-vetch mixtures than the pure stand of vetch (Tables 3.5.1 and 3-5.4) while thcre
was no significant difference in plant density between pure stands of oats or oats-vetch
mixed stands. Similarly nitrogen fertilizer had no significant effect on plant
establishment (Table 3.5.1 and 3.5.2).
119
Table 3.5.1. Summary of ANOVA on ptant establishment and yield of
different oat cultivars and vetch species when plant establishment
and yield was statistically analysed for cultivar and species
differences.
Source of variation Plants/m2 Yield (kgDltf/ha)
(Days after sowing)
55 83 118 145
Species
Sowing ratios
Nitrogen
Species x Sowing ratios
Species x Nitrogen
Sowing ratios x Nitrogen
***
***
n. s.
n.s
n.s
n. s.
n.s.
***
***
***
*
n. s.
n.s
n.s.
**,ft
*{<*
*{<*
***
***
n.s.
n.s.
***
***
***
n.s.
***
n.s.
n. s.
***
**rt
***
***
n. s.
n. s.
,F
Species x Sowing ratios x
Nitrogen
Table 3.5.2. Summary of ANOVA on plant estabtishment and yield of
different oat cultivars and vetch species when data for
estabtishment and total yield of oats and vetch was statistically
analysed.
Sou¡ce of variation Plants/m2 Yield (kgDlvVha)
(Days after sowing)
83 118 14555
Sowing ratios
Nitrogen
Sowing ratios x
Nitrogen
*,k {<
n. s. *dc*
**,****
***:1.*
******
n.s. n. s. :l.d<* ,l.r<* ¡1. {.
120
Table 3.5.3. Density (plants/m2¡ of oat cultivars and vetch species sown
as pure and mixed stands.
Species Sowing ratios Mean
Pure stand (1 Mixed stand (50:50)
Coolabah oats
Dolphin oats
Nanroi vetch
203
r32258
265
220
2t8
140
113
110
195
t66
t&Popany vetch
Species
Sowing ratios
*** LSD (P=O.05) = 11
LSD (P{.05) = 3*,$*
Species x Sowine ratios n.s.
121
Table 3.5.4. Density of oat cultivars and vetch species at various sowing
ratios sown with and without nitrogen fertilizer.
(IÆ transformed data: fi gures in oarenthesis are the means of orieinal data)
Sowing ratios Nitrogen treatments (kg/ha)
0 50
Mean
Oats:Verch
Plants/m2
0:100
50:50
100:0
s.42(226)
s.s0(24s)
s.ss(2se)
s.36(212) s.39(2r9)
s.s2(249) s.5r(247)
s.s7(264) s.s6(262)
Mean 5.49 (243\ 5 .48(.242\
Sowing ratios
Nitrogen
***
n.s
n. s.
LSD (P=0.05) = g.g5
Sowing mtios x Nitrogen
Table 3.5.1. presenrs a summary of the data when statistically analysed for
differences between oat cultivars and vetch species during the growing season. Table
3.5.2 summarizes of significant differences between sowing ratios when the data was
statistically analysed for total mean yield (oats + verch).
The mean DM accumulation is shown for all harvests of oat cultivars and vetch
species in Table 3.5.5 and Appendix Figure 5.12. The DM yield of of both oat cultivars
was significanrly higher than the DM yield of both vetch species throughout the season
except 55 days after sowing when the DM of Coolabah oats was similar to that of Namoi
vetch. Oats cv. Dolphin produced significantly more DM yield than Coolabah oats at all
stages of growth. The mean DM yield obtained from Namoi vetch was significantly
higher than Popany vetch in the early part of the season (i.e. 55 and 83 days after
sowing). However in the later part of the season there was no significant difference in
DM production between vetch species.
122
Table 3.5.5. Totat yield of oat cultivars and vetch species sown as pure
and mixed stands with and without nitrogen fertilizer at various
stages of growth. '
Species Yield (kÐlt¡Ilha)
(Days after sowing)
55 83 118 145
Coolabah oats
Dolphin oats
Namoi vetch
Popany vetch
293
377
295
209
r524
2204
rt79
943
5947
736r
3745
3465
10139
10918
5409
5423
LSD (P=0.05 43) 131 469 675
Table 3.5.6 shows the mean DM yield of oat cultivars and vetch species sown as
pure stands and mixtures at different stages of maturity during the season. The DM yield
obtained from the pure stand of oats or oats-vetch mixed stand was significantly higher
than the pure stand of vetch at all stages of growth. There was no significant difference
in the DM yield of the pure stand of oats or the oats-vetch mixed stand throughout the
season except 83 days after sowing, when the DM production from the pure stand of
oats was significantly higher than the mixed stand of oats and vetch.
There were significant interactions between species and sowing ratios in DM
production of oat cultivars and vetch species 55, 83 and 145 days after sowing (fables
3.5.1, 3.5.7, 3.5.8, 3.5.9). Both the oat cultivars and vetch species produced
significantty higher DM yield in pure stands than the DM yield produced by these
cultivars and species in the mixed stands 55, 83 and 145 days after sowing. At 55 days
after sowing, significantly higher DM yield was obtained from the pure stands of
Dolphin oars and Namoi vetch followed by Cootabah oats, while the lowest DM
production occurred with Popany vetch. In the oats-vetch mixed stand there was no
signihcant difference in DM yield within oat cultiv¿ìrs or between Coolabah oats and
123
Namoi vetch or within vetch species. The trend in DM yield in the pure stand of oats
and vetch changed at between 83 and 145 days after sowing. Oats cv. Dolphin out-
yielded Coolabah oats and boih vetch species in a pure stand 83 days after sowing.
There was no significant difference in the pure stand of Coolabah oats or pufe stand of
Namoi vetch at this stage of maturity. At 145 days after sowing, the DM yield of both
oat cultivars in pure stands was significantly higher than that of the pure stand of vetch.
There \ryas no significant difference in DM production between oat cultivars or between
vetch species in the pure stands. However, DM yield obtained from oats Dolphin in the
mixed stand was significantly higher than Coolabah oats or vetch species 83 and 145
days after sowing. The DM production of Coolabah oats in the mixed stand was
significantly higher than the vetch species 83 and 145 days after sowing.
Table 3.5.6. Total yietd at various stages of growth of oat cultivars and
vetch species sown as pure stands and mixed stands.
Sowing ratios Yield (kÐlvl¡ha)
(Days after sowing)
Oats:Vetch 55 83 118 t45
0:100
50:50
100:0
343
428
404
1489
2039
2296
4953
7501
8063
7239
lr74l
12478
LSD (P=0 .05) 46 220 570 975
124
Table 3.5.7. Yield, 55 days after sowing of oats cultivar and vetch
species sown as pure stands and mixed stands.
Species Sowing ratios and Yield (kgDlvfha) Mean
Pure stand (lû07o\ Mixed stand (50:50)
293
377
295
209
240
292
180
t4l
346
462
409
278
Coolabah oats
Dolphin oats
Namoi vetch
Popany vetch
Mean 374 213
Species
Sowing ratios
***
{.* r*
LSD (P=0.05) = 43
LSD (P=0.05) = 39
LSD (P=0.05) = 61Species x Sowing ratios *
125
Table 3.5.8. Yield, 83 days after sowing of oat cultivars and vetch
species sown as pure stands and mixed stands'
Species Sowing ratios and Mean
Pure stand ( lffiVo\ Mixed st¿nd
Coolabah oats
Dolphin oats
Namoi vetch
Popany vetch
1852
2771
1676
1303
tt96
1637
583
1524
220/i
tr79682
943
Mean 1900 1024
Species
Sowing ratios ***
***
***
LSD (P=0.05) = 131
LSD (P=0.05) = 93
LSD = 185Species x Sowing ratios
126
Table 3.5.9. Yield, l.4S days after sowing of oat cultivars and vetch
species sown as pure stands and mixed stands.
Species Sowing sowing ratios and Yield (kgDlvf/ha) Mean
Pure stand (lOO7o\ Mixed stand (50:50)
Coolabah oats
Dolphin oats
Namoivetch
Popany vetch
t2t94
13347
7323
7176
7483
8489
3494
3671
10139
10918
5409
5423
Mean 10160 5784
Species ***
***
LSD (P=0.05) = 675
LSD (P=0.05) = 477Sowing ratios
Species x Sowing ratios LSD (P=0.05) = 955
The use of nitrogen fertilizer significantly increased the mean DM yield of oats
and vetch species at all stagcs of unturity (Table 3.5.10 and Figurc 3.5.3). There was
also a species x nitrogen interaction at various stages of growth. At 83 days after
sowing the DM yield of oat cultivars was significantly increased by adding nitrogen
whereas the DM yield of vetch was affected by nitrogen (Table 3.5.11). Oats cv.
Dolphin produced significantly higher DM yield than cv. Coolabah both in control and
nitrogen-üeated plots and the DM yield of Namoi vetch was greater than that of Popany
{<
vetch
127
Table 3.5.10. The effects of nitrogen fertilizer on the mean yield
(kgDM/ha) at various stages of growth of oat cultivars and vetch
species sown as puie and mixed stands.
Days after sowing
(P=0.05)
Nitrogen treaÍnents (kg¡ha) I-SD
500
30
93
332
477
33425355
83 t2ll tt13
118 4851 5408
145 7370 8575
Tabte 3.5.11. The effects of nitrogen fertilizer on the yield 83 days after
sowing of oat cultivars and vetch species.
Species Nitrogen treatrnents (kglha) Mean
500
Coolabah oats
Dolphin oats
Namoi vetch
Popany vetch
1096
t776
tt25
848
t952
263r
1233
1037
t524
2204
rt79
943
Mean r2ll t7t3
Species
Nitrogen
*,ß*
***
LSD (P=O.05) = 131
LSD (P=0.05) = 93
Species x Nitrosen {.:t*€ LSD æ=0.05) = 185
128
Similarly, the use of nitrogen fertilizer significantly increased the DM yield of oat
cultivars but there was no significant difference in DM yield of vetch species 118 days
after sowing (Table 3.5.12). The DM yield of Dolphin oats both in control and nitrogen
treated-plots \¡/as significantly higher than Coolabah oats, while there was no significant
difference in DM yield of vetch species. Both oat cultiva¡s produced signifrcantly higher
DM yield than vetch species in control and nitrogen-üeated plots.
Table 3.5.L2. The effects of nitrogen fertilizer on the yield (kgDM/ha)
of oat cultivars and vetch species 118 days after sowing.
Species Nitrogen treatments (kg/ha) Mean
500
Coolabah oats
Dolphin oats
Namoi vetch
Popany vetch
5594
6352
3954
3506
6300
8370
3536
3425
5947
736r
3745
3465
Mean 4851 5408
Species
Nitrogen
***
***
*{<*
LSD (P=0.05) = 469
LSD (P=0.05) =332
LSD (P=0.05) = 664Species x Nitrogen
At the next sampling date nitrogen fertilizer signihcantly increased DM yield of
both oat cultivars (Table 3.5.13); while the use of nitrogen fertilizer significantly
129
depressed DM yield of Namoi vetch and had no effect on Popany. There was also no
significant difference in DM production within oats cultivars in nitrogen-treated plots.
However, the DM yield of Doþhin oats was signifrcantly higher in control plots than
Coolabah oats. There was no significant difference in DM production within vetch
species between control and nitrogen treated ploß.
Table 3.5.13. The effects of nitrogen fertilizer on the yield (kgDM/ha)
of oat cultivars and vetch species 145 days after sowing.
Species Nirogen treafrnents (kglha) Mean
500
Coolabah oats
Doþhin oats
Namoivetch
Popany vetch
8323
9901
5920
5335
r1954 10139
I 1935 10918
4898 5409
5512 5423
Mean 7370 8575
Species
Nitrogen
*{<*
*:1.*
***€
LSD (P=0.05) = 675
LSD (P=O.05) = 477
LSD (P=0.05) = 955Species x Nitrogen
Yietd of We¿ds: Weeds, mainly wild oats (Avenafatua) and soursob (Oxalis pes-
caprae),were present in many of the plots. Their growth and the effect of the different
treatments were assessed by separating the weeds from the oats and vetch in pure and
mixed stands. Table 3.5.14 summarizes the significant differences in weed DM yield
between sowing ratios, nitrogen and the interaction between sowing ratios and nitrogen.
There was no significant effect of sowing ratios on weed DM yield 55 days after sowing
(Tables 3.5.74,3.5.15). However weed DM yield was significantly higher in the pure
130
stands of vetch 83, 118 and 145 days after sowing. There was no difference in the
amount of weed gowth in the stands of oats or oats/vetch except 118 days after sowing.
Nitrogen fertilizer had no sigéificant effect on weed DM yield throughout the season
(Table 3.5.14).
Table 3.5.14. Summary of ANOVA of weeds yield from plots of oat
cultivars and vetch species sown as pure and mixed stands.
Source ofva¡iance Yield (kgDlvl/ha)
(Days after sowing)
83 11855 r45
***t<* {(**Sowing ratios
Nitrogen
n.s.
n.s n. s. n. s.
n.s
n.s.
n.s.Sowing ratios x
Nitrogen n.s. n. s.
Table 3.5.15. Mean weed yield at various stages of growth from plots of
oat cultivars and vetch species when sown as pure and mixed
stands.
Q-og transformed data: figures in parenthesis are the means of original dat4
Data averaeed for niuosen
Sowing ratios V/eeds yield (kgDlvllha)
(Days after sowing)
118Oats:Vetch 55 83 145
0:100
50:50
1ü):0
4.6e(1S3) 6.02(ss0) 6.08(723) 4.84(584)
4.s2(15s) s.r7(272) s.09(2s3) 2.s6(ss)
4.58(159) s.o4(274) 4.3s(19e) 2.78(ss)
LSD n.s. 0.60 0.66 0.98
131
3.5.3.2 Plant Height
It is evident from the éummary of the ANOVA in Table 3.5.16 that there were
significant effects on plant height of species, sowing ratios, nitrogen and the interaction
between these treatments. The mean plant height of oats cultivars and vetch species
varied significantly within the cultiva¡s and species (Table 3.5.17). Both the oats
cultivars were significantly taller than the vetch species. The mean plant height of oats
cv. Coolabah was significantly greater than that of Dolphin oats. Similarly Popany vetch
was significantly taller than Namoi.
The Species x Sowing ratios interaction shows that Coolabah oats was
significantly taller in pure stand than the oats-vetch mixed stand, while there was no
significant difference in plant height of Dolphin oats between pure or oats/vetch mixed
stand. On the other hand, plant height of vetch species was significantly higher in the
oats/vetch mixed stand than the pure stands of these species. The mean plant height of
oats cultivars and vetch species increased significantly with the application of nitrogen
fertilizer (Tables 3.5. 16, 3.5. 18).
3.5.3.3 Number of Tillers
The summary of significant differences for oat tiller number is given in Table
3.5.16. There was no significant difference in the mean tiller number within oats
cultivars both sown as pure or mixed stands with vetch. However, the mean tiller
number of oats in pure stand was significantly higher than the tiller number of oats in the
mixed stand (Table 3.5.16). Also the nitrogen fertilizer significantly increased the mean
tiller number of oats (Table 3.5.19).
132
Tabte 3.5.f6. Summary pf ANOVA of plant height, number of tillers'
grain yield and grain weight of different oats cultivars and vetch
species.
Source of variation Plant height Tillers Grain yielda Grain yietdb Grain
weight(mm) (*trû\ (kg/ha) (kgha) (s,/100)
Species/Cultiva¡s
Sowing ratios
Nitrogen
Species x Sowing ratios
Species x Nitrogen
Sowing ratios x Nitrogen
Species x Sowing ratios x
Nirogen
*{<
*** n. s.
*** ***
***
*** n. s.
n. s. n.s
n. s. n. s.
n.s n.s.
***
n.s
n.s.
**rt
***
n. s.
n.s.
n.s.
n.s
***
n.s.
n.s.
***
n.s.
n.s.
n. s.
*
'¡ill,fiirI
a. Total mean grain yield (oats + vetch) when the data was statistically analysed for total
yield at different sowing ratios.
b. Mean grain yield (kg¡ha) of oats and vetch when the data was statistically analysed for
cultivars and species differences.
tïI
I
3
133
al
Table 3.5.17. Plant height of oats and vetch sown as pure stands and
mixtures.
Species Sowing mixture Mean
Pure stand (1007o) Mixed stand (50:50)
Coolabah oats
Dolphin oats
Namoi vetch
Popany vetch
927908
1226
946
520
s80
Height (mm)
1047
827
919
tt37
673
750
Mean 818 925
Species
Sowing ratios
Species x Sowing ratios
*** LSD (P=0.05) = 35
:*tk* LSD (P=0.05) = 25
¡t** LSD (P=0.05) = 49üi
I
r
134
II
I,i, .þl
il
l
Table 3.5.18. The effects of nitrogen fertilizer on plant height of oats
and vetch.
Species Nitrogen trsatments (kglha) Mean
0 50
Height (mm)
tt37
9n
673
750
1168
945
682
763
889
1105
909
66s
736
854
Coolabah oats
Doþhinoats
Narnoi vetch
Popany vetch
Mean
Species
Nitrogen
LSD (P=0.05) = 35
LSD (P=0.05) = 25
:***
**
n. s.Species x Nitrogen
I
ilTif
I
I
I
i
I
It
I
r
I
135
Table 3.5.19. The effects of nitrogen fertilizer on the mean tillers
number of oat cultivars sown as pure and mixed stands with vetch
species with and without nitrogen fertilizer.
Species Nitrogen treatments (kdha) Mean
500
TillerVm2
303
309
334
324
321
343
344
347
285
276
323
300
Coolabah+Namoi
Coolabah+Popany
Dolphin+Namoi
Dolphin+Popany
Mean 296 339
,I
Species
Nitrogen
n. s.
:ß{.*
n.s
LSD(P=0.05) =20
Species x Nitrogen
I
3.5.3.4 Grain Yield
The summary of the main effects of the treatments on the grain yield of oat
cultivars and vetch species are shown in Table 3.5.16. It is apparent from Table 3.5-20
that mean total grain yield from pure stand of oats was signifrcantly higher than the pure
vetch or oats-vetch mixed stand. The mean grain yield obtained from the mixed stand of
oats-vetch was significantly higher than the grain yield obtained from pure vetch stand.
!Both oats cultivars and vetch species produced significantly higher grain yield in
136
pure stand than the grain yield of these cultivars and species in the mixed starid (Table
3.5.21). The grain yield of oat cultivars Coolabah and Dolphin was significantly higher
than the grain yield of the two vetch species when gtown either as pure stands or mixed
stands. There was no significant difference in grain yield between vetch species in pure
stand, but in the mixture, the grain yield of Namoi vetch was significantly lower than that
of Popany.
Table 3.5.20. The effects of different sowing ratios on the total grain
yield (oats + vetch) of two oat cultivars and vetch spec¡es with and
without nitrogen fertilizer.
Sowing ratios Nitrogen treatments (kg/ha) Mean
Oats:Vetch 500
0:100
50:50
1ü):0
1048
3759
6212
Grain yield (kg/ha)
1046
4559
6lM
r047
4t59
6178
Mean 3673 3916
Sowing ratios
Nitrogen
*** LSD çt=6.05) = 634
n.s.
Sowins ratios x Nitroeen n.s.
137
Table 3.5.21. Mean grain yietd of different oat cultivars and vetch
species sown as pure stands and mixed stands'
Species Sowing mixture Mean
Pure stand (lÙOVo) Mixed stand (50:50)
Coolabah oats
Dolphin oats
Namoivetch
Popany vetch
Grain yield (kg/ha)
6.31(ss20) s.74(3350) 6.03(4440)
6.s2(6790) s.s7(3820) 6.1e(s300)
4.s7(980) 3.61(3e0) 4.0e(e40)
4.72(rr20) 4.23(7s0) 4.48(940)
Mean 5.s3(3600) 4.86(2080)
Species
Sowing ratios
*{<*
,1.**
* {<rk LSD
LSD (P=0.05) = 9.17
LSD (P=0.05) = 6.12
= 0.24Species x Sowing ratios
3.5.3.5 Grain Weight
Table 3.5.16 summarizes the differences in the mean 100-grain weight between
species sowing ratios, nitrogen and their interaction. There was no significant difference
in the mean grain weight between the two vetch species. The mean 100 gnin weight of
vetch species was significantly higher than the mean grain weight of oats cultivars (Table
3.5.22). The mean grain weight of Coolabah oats was signifîcantly higher than the
mean grain weight of Dolphin oats in both pure and mixed stands. It is evident from the
Species x Sowing ratios interaction that there was no signif,rcant difference in the mean
138
grain weight of oats cv. Coolabah between the pure and mixed stands. On the other
hand the mean grain weight of Dolphin oats was significantly depressed in the mixed
stand compared to the pure stand. Similarly the mean grain weight of Popany vetch was
similar for the pure and mixed, stand while the mean grain weight of Namoi vetch was
significantly higher in the mixed stand compa¡ed to the pure stand. Nitrogen fetilíznr
had no effect on the mean grain weight of either oats cultivars or vetch species (Table
3.s.16).
Table 3.5.22. Mean grain weight of different oat cultivars and vetch
species sown as pure and mixed stands.
Species Sowing mixture Mean
Pure stand 000Vo) Mixed stand (50:50)
Coolabah oats
Dolphin oats
Namoi vetch
Popany vetch
3.r3
2.86
4.29
4.48
Grain weight (9100)
3.O7
2.46
4.55
4.50
3.10
2.66
4.42
4.49
Mean 3.69 3.65
Species
Sowing ratios
***
***
LSD (P=0.05) = 9.17
LSD (P{.05) = 9.12
Species x Sowing ratios *** LSD (P=0.05 \ = 0.24
139
3.5.3.6 Soil Moisture
The gravimetric water content of the soil was estimated by taking soil samples at
two depths during the the later part of the season. The summary of significant
differences in soil moisture percentage between species, depths and species x depths
interaction is given in Table 3.5.23. There were significant differences in soil moisture
between species at all sampling dates except 137 days after sowing (Table 3.5.24). T\e
soil moisture contents was significantly higher in pure plots of Popany and Namoi than
mixed plots of oats-vetch or pure oats 150 days after sowing. There was no significant
difference in soil moisture percentage between mixed plots of Coolabah and Popany or
pure Coolabah and Dolphin oats. The soil moisture content was significantly lower in
the mixed plots of Dolphin and Namoi but was similar to the pure stand of Coolabah
oats. There was no signifrcant difference in soil moisture contents between plos of pure
stand of Popany, Namoi, Dolphin and mixed stand of Coolabah and Popany 173 dayi
after sowing. The soil moisture percentage was signifrcantly lower in plots sown with
pure Coolabah oats and mixed plots of Dolphin and Namoi. In addition, the soil
moisture percentage was not significantly different between pure stand of Coolabah oats
or mixed plots of Dolphin and Namoi. Similarly there was no signihcant difference in
soil moisture content between plots of pure Popany, Coolabah, Namoi, Dolphin and
mixed stands of Coolabah and Popany 198 days after sowing. The soil rnoisture content
was significantly lower in plots sown with a mixture of Dolphin and Namoi but similar
to pure stand of Coolabah and Dolphin oats.
There were also significant differences in soil moisture contents between depths
at all sampling stages (Table 3.5.25>. The soil moisture percentage was significantly
higher at a depth of 30-60 cm than 0-30 cm.
140
Table 3.5.23. Summary of ANOVA of soil moisture percentage in oats,
vetch pure and mixed plots at late stages of maturity'
Source of variation Soil moisture ToaSe
(Days after sowing)
t37 r50 173 198
n.s rk** ,t**
*** *** *** ***
Species x Depths n.s. n.s n.s. n.s.
Table 3.5.24. The effects of different oat cultivars and vetch species
sown as pure stands and mixed stands on the mean soil moisture
percentage at late stages of maturity (Average of two depths).
*Species
Depths
Species Soil moistureVoage
(Days after sowing
r37 150 173 198
Ccnlabah (Pure)
Coolabah + Popany (Mixed) 15.09 t5.64
Popany (Pure) 14.05
t2.74 t4.96 r0.24 t5.49
13.43 16.97
18.14 t3.97 16.78
t3.9r 15.60 13.16 1s.89
11.03 14.39
16.51 19.18 13.32 t6.44
Dolphin (Pure)
Dolphin +Namoi (Mixed) 13.22 13.83
Namoi (Pure)
LSD n. s. 1.54 1.89 r.62
141
Table 3.5.25. The mean soil moisture content at two depths at late stages
of maturity (Average overall species and mixtures).
Days after sowing Sampling depths
G30 cm 30-60 cm
LSD (P=0.05)
r37
150
173
9.94
10.08
7.36
Soil moisture (7o)
18.56
22.37
t7.69
22.02
3.6r
0.90
1.09
0.94198 9.96
3.5.3.7 Soil Mineral Nitrogen
Table 3.5.26 summarizes the significant differences in soil total mineral nitrogen
between species, depths and species x depths interaction at various stages of growth.
There were significant differences in the mean soil total mineral nitrogen between plots
of oats and vetch sown as pure and mixed stands 70, 128 and 197 days after sowing
(Table 3.5.27 and Appendix Figure 5.11). However, the difference in the mean total
mineral nitrogen between these plots were not significant 34 and 101 days after sowing.
The soil total mineral nitrogen concentration was significantly higher in pure vetch plots
than pure oats or oars-vetch mixed plots at sampling dates of 70, L28 and 197 days after
sowing. During these sampling stages, there was no significant difference in the mean
soil total mineral nitrogen between pure oats plots or oats-vetch mixed plots.
142
Table 3.5.26. Summary of ANOVA of soil total mineral nitrogen (ppm)
in oats and vetch pure stands and mixtures.
Source of variation Days after sowing,)
34 70 101 128 r97
Sowing ratio
Species
Depttrs
n.s.
n.s: **,F
n.s.
n.s ***
*¡ttt
***
***
***Sowine ratio x Deoths n.s. n.s.
Table 3.5.27. The effects of oats and vetch in pure stands and mixed
stands at various stages of growth on soil total mineral nitrogen
(ppm).
Days after sowing
(P=0.05)
Sowing ratios LSD
Pure vetch
stand
Oats-vetch
mixed stand
Pure oats
stand
34
70
101
t28
17.4
6.r6
4.25
5.7 5
20.9
s.03
4.O9
3.64
15.3
5.23
3.71
2.68
n.s.
0.81
n.s.
r.62
r97 t3.r2 7.51 3.43 4.36
143
Simitarly there was no significant difference in the mean soil total mineral
nitrogen berween depth of 0-15 cm or 15-30 cm at 34 and 101 days after sowing (Iable
3.5.26 and 3.5.28 and Appendix Figure 5.12). The concentration of soil total mineral
nitrogen was significantly higher in the G15 cm layer than ttre 15-30 cm layer at 70,128
and 197 days after sowing.
There were significant Species x Depths interaction in the case of soil total
mineral nitrogen during the sampling dates. The concentration of soil total mineral
nitrogen at 0-15cm was significantly higher in pure vetch plots at a depth of 0-15 cm
than in oats either pure or the oats-vetch mixed stands The concentration of soil total
mineral nitrogen was similar in plots of pure oats or oats-vetch mixed stand at 0-15 cm
depth. At a depth of 15-30cm however, there was no significant difference in soil total
mineral nitrogen between plots of pure oats, pure vetch and oats-vetch mixed stands.
Table 3.5.28. Soil total mineral nitrogen (ppm) at various stages ofgrowth two depths in plots of õats ánd vetch sown as pure standsand mixtures.
Days after sowlng Sampling depths
15-30 cm
LSD
0-15 cm
34
70
101
r28
197
18.7
6.80
3.84
5.72
t3.17
t7.l
4.t5
4.20
2.32
2.87
n.s
0.66
n.s
r.33
3.56
144
Table. 3.5 29. The effects of oats and vetch in pure stands and mixed
stands on so¡l total mineral nitrogen (ppm) at two depths' 70
days after sowirig.
SamplingSowing ratiodepths (cm) Mean
0-15 15-30
Pure oats
Oats-verch mixture
Pure vetch
5.88
6.6s
7.88
4.59
3.42
4.45
5.23
5.03
6.16
Mean 6.80 4 15
Sowing ratios
Depths *¡**
*
:*
LSD 1t=9.05) = 9.31
LSD (P=0.05) = 9.66
LSD (P=0.05) = 1.15Sowing ratio x Depths
Tables 3.5.30 and 3.5.31 illustrate significant Species x Depth interaction in soil
total mineral nitrogen between pure oats, vetch or mixed plots of oats-vetch 128 and t97
days after sowing respectively. In both sampling stages significantly higher soil total
mineral nitrogen was recorded in plots of pure vetch or mixed oats-vetch stands at a
depth of 0-15 cm than at 15-30 cm in pure stands of vetch or oats-vetch mixed plots.
There was no significant difference in the soil total mineral nitrogen between 0-15 and
15-30 cm depths in pure stands of oats, both 128 and 197 days after sowing. The soil
total mineral nitrogen concentration at a depth of 0-l5cm was significantly greater under
pure stands of vetch than the pure starids of oats or oats-vetch mixed stand at Gl5 cm or
pure stand of oats, vetch and mixed stands However, at 15-30cm there was no effect of
sowing ratios on mineral nitrogen concentration.
145
Tabte. 3.5.30. The effects of oats and vetch in pure stands and mixed
stands on soil total mineral nitrogen (ppm) at two depths 128
days after sowiúg.
SamplingSowing ratiodepths (cm) Mean
0-15 15-30
Pure oats
Oats-vetch mixture
Pure vetch
3.43
4.90
8.84
t.93
2.38
2.66
2.68
3.64
5.75
Mean 5.72 2.32
Species
Depths
Sowing
:F*
rß
***
LSD (P=0.05) = 1.62
LSD (P{.05) = 1.33
LSD (P=0.05) = 2.29ratio x Depths
Table. 3.5.31. The effects of oats and vetch in pure stands and mixed
stands on soil total mineral nitrogen (ppm) at two depths' 197
days after sowing.
Sowing ratio Sampling depths (cm)
0-15 15-30
Pure oats
Oats-vetch mixture
Pure vetch
5.42
13.72
20.37
t.43
r.29
5.88
3.43
7.5r
13.12
Mean 73.r7 2.87
Species
Depths
Sowins
***
**(*
LSD (P=0.05) = 4.36
LSD (P=0.05) = 3.56
LSD (P=0.0Ð = 6.17*ratio x Deoths
1 45a
Plate 3.5.1 Illustration of the heights of the two oat cutivars,
Coolabah (left) and Dolphin (right) at stem elongation (above)
and panicle emergence (below).
\
\l\'
146
7.4. DISCUSSION
Dolphin generally produced more DM yield than Coolabah whether as a pure
stand or a mixture. It also produced more DM when nitrogen was added but its response
to nitrogen was not greater than that of Coolabah. The reason for similar DM yield of
both cultivars of oats in the pure stand in the later part of the season Clable 3.5.9) is due
to the height differences of the two. Coolabah oats is taller than Dolphin oats (fable
3.5.17 and Plate 3.5.1) although no attempt was made to estimate plant height before the
booting stage of the crop, it was observed that difference in ptant height between
Coolabah and Dolphin oats were only obvious after the booting stage (Plate 3.5.1).
Hence the height of Coolabah oats in the later part of the season may have contributed to
the observed DM differences between these cultivars at the later stages of growth.
Nitrogen fertilizer increased total DM yield, number of tillers and plant height in
oats. A strong effect of nitrogen fertilizer on tillering has been recognised in cereals
(Langer 1966) and similar results have been shown in pot culture by other workers
(Thorne 1962; Bremner 1969). Similarly, increased nitrogen supply has caused wheat
to grow taller. This has been demonstrated in both pot experiments (V/atson 1963) and
field experiments (Russell and Rohde 1963). The early g¡owth of both species of vetch
was increased with the addition of nitrogen. Low soil temperatures during winter not
only reduce the rate of fixation of atmospheric nitrogen by legumes (Gibson 1963) but
also reduce the rate of mineralisation of organic nitrogen to available forms @lackman
1936). Hence the vetch species may have responded to the applied nitrogen fertilizer in
the early stage of gowth (Crofts 1966) when the supply of nitrogen from symbiotic
fixation was low. The decrease in DM yield of vetch species with added nitrogen is due
to the increased competition from the oat cultivars. Nitrogen fertilizer favoured the
growth of oat cultivars much more than the vetches and may have affected the DM yield
of vetch species. These results are in agreement with the previous findings of Kamprath
et at. (1958) and WasseÍnann et al. (1984).
The variation in weed DM yield in plots of oats and vetch sown as pure and
147
mixed stands is mainly because of the prcsence of wild oats on the site. The separation
of wild oats from pure vetch stand was possible while it was difficult from mixed
oats/vetch or stands of pure oat;. So the results may reflect this rather than show greater
suppression of weed gfowth when oat was grown either as a pure stands or in mixturc'
The greater DM production of Dolphin oats throughout the season was expected
to be seen in greater grain yield as well (Salman and Brinkman 1990) but both cultivars
produced similar grain yield. No attempt was made in the present experiment to measr¡ne
grain yield components e.g. grain per panicle or grain per pod, number of fertile florets
or number of fertile tillers/m2: however mean 100-grain weight was lower in cv. Dolphin
than Coolabah. This may have contributed to the low grain yield of Dolphin oats and led
to the similar grain yield of Coolabah oats. Even et al. (1975) reported that cultivar
differences in grain size are associated with differences in grain yield. The low mean
grain yield of Namoi vetch compared to Popany vetch in the mixed stand may be due to
the height differences between the species. Popany vetch was taller than Namoi and this
may have favoured Popany vetch to compete better than Namoi in the mixed stand
during the later part of the season.
In general, plants with a low production rate usually have a low uptake demand
(reported by Cole (1931) and cited by Haynes et at. (1986), although it is not clea¡ that a
low production rate limits nitrogen uptake or a low uptake limits production. Thc higher
concentration of soil total mineral nitrogen in plots of pure vetch compared to pure oats
or oats/vetch mixed plots may be due to their lower productivity as well as to species
differences. Mengel (1983) reported variable absorption, translocation and utilization of
soil and fertilizer nitrogen by different species and genotypes of plants. Vetch being a
legume,; gets some of its nitrogen from N2-f,rxation and some of the nitrogen which is
not mineralised from the organic matter is not used by the vetch and can accumulate
during the season. The increase in mineral nitrogen later in the season is probably due to
mineralization of organic matter as soil temperatures rise in spring . Most of the organic
matter is located in the surface leyer of soil (0-15cm) and the increases occurred mainly
in this layer; 15-30cm, soil mineral nitrogen levels declined throughout the season
148
(Table 3.5.28).
The soil moisture readings showed that the soil tended to be moister under pure
vetch, but apart from this there were few consistent trends. This experiment showed that
the DM production of an oats:vetch mixture can be substantially greater than that after
pure vetch crop and equal to a pure oat crop. Both the choice of oat cultiva¡ and of veæh
species can affect DM production throughout ttre growing season, although the choice of
oat appears to be more important. The experiment also showed that there may be greater
residual nitrogen following a vetch crop, but this benefit declines when an oat is grown
with verch.
4. GENERAL DISCUSSION
The series of field eiperiments described in this thesis were undertaken to
evaluate cultural factors that may affect the quality and quantity of cereal and legume forage
production. Five experiments were carried out at the rü/aite Agricultural Research Institute
during the 1988 and 1989 growing seasons. Three field experiments were conducted in
the first season (1988) as follows:
(1) a quantitarive and qualitative evaluation of different cereal cultivars and vetch
species for forage production;
(2) an evaluation of the dry matter production and nutritive value of oats medic
and verch sown at various densities;
(3) a comparison of the dry matter yield and nutritive value of oats, medic and
vetch in pure stands and mixtures.
In the second growing season, 1989, two major field experiments were
conducted as follows:
(4) an extended study of oats and vetch sown at various sowing ratios, sowing
rates and nitrogen treatments: the influence of these fteatments on oats and vetch forage
yield, forage quality at successive stages of growth, grain yield and quality was
investigated;
(5) an experiment designed to examine the effect of differences in plant height of
oat cultivars and vetch species, grown alone or as mixtures with or without nitrogen
fertilizer on DM and grain yield. Also the effects of oats and vetch in pure stands and
mixtures on soil total mineral nitogen and moisture status were Studied.
In the separate discussions of these experiments the results of each experiment
and some of their relationships were discussed. This general discussion seeks to interpret
the findings.
150
Intensive cropping systems as alternatives to pasture have received increased
attention to increase forage production and hence potential animal production,(Crowder et
at.1954; Ciha 1983; Sæphen et al.1977} Some workers (e.g. Oplinger and Young 1975;
Brown and Almodares 1976; Stephen et at.1977; Morey 1979; Dann 1980; Cherney and
Marten 1982; Ciha 1983; Graham et al. 1983; Hughes and Haslemofe 1984) have
compared a range of winter cereals for dry matter production and nutritive value a¡round
the world, while others (e.g. Ahlgern et al.1954: Spurway et al. 1975; Bowdler and Lowe
1980; Rao and Willey 1980; Dahmane and Graham 1981; Osman and Osman 1982; Osman
and Nersoyan 1986; Moreira 1989; Robert et al. 1989) have investigated the dry matter
production of cereaVgrass and legume, either alone or in mixtures.
The winter forage production obtained in both growing seasons was found to be
dependant on sowing rates. In the first gfowing season the mean dry matter yield of oats,
medic and vetch 45 and 73 days after sowing ,was approximately 4 and 2 fold greater at a
sowing rate of 500 compared with 100 kglha, 45 and 73 days after sowing. Similarly, in
the second growing season the mean dry matter yield of oats and vetch sown at 50' 100
and 200 kg sowing rates/ha was 2.8 (oats),2 (vetch) and 1.8 (oats), 1.5 (vetch) greater at
the higher sowing rate of 2}}kglha than at 5Okglha and 100 kg/ha, 48 and 76 days after
sowing respectively. The dependance of early winter forage production on higher sowing
rates of several plant species was noted earlier by Donald (1951, 1954), Crofts (1966b)
and Robinson and Sykes (1973). The higher dry matter yield from high sowing rates in
the earlier stages of growth is because of higher numbers of seedlings per unit area. In the
later part of the season the forage production at higher sowing rates is similar to that at
moderate sowing rates because of plant mortatity/self+hinning due to competition- Donald
(1951) has shown that intra-specific competition among annual pasture plants increased
with density at advancing stages of growth and with decreased soil nutrient status- If the
emphasis is on early forage production from forage crops, the higher sowing rates will
give maximum dry matter yield per unit area while moderate sowing rates will give similar
dry matter yield to that of higher sowing rates by the end of the season.
i,jr,È
¡
I
r
151
The higher sowing rates of oats, medic and vetch süongly depressed the dry
matter yield of weeds. For example, at the end of the first growing season the weed dry
matrer yield was 6.2 and 1.2 fold greater at 50 and 100 than 500 kg sowing rates/ha of
oats, medic and vetch rcspectively (Table 3.2.9). Similarly in the second growing season
weed dry marter yield was 1.8 and 2.1 greater at 50 and 100 than 2OOkglha sowing rates
of oats and vetch respectively (Table 3.4.13). These results support the findings of other
workers (e.g. Ervio 1972;Barret and Campbelt 1973; O'Donovan and Sharma 1983).
The effects of sowing rates on herbage crude protein percentage was not
significant in the first season. This may be due to the presence of weeds on the site which
may have competed with the sown species and hence reduced the effects of sowing rates
of oats, medic and vetch on crude protein percentage of these species. In the second
growing season there was a trend to higher herbage crude protein percentage at low
sowing rates compared to high sowing rates. However, the trend was not consistently
signif,rcant throughout the growing season. Donald (1951) recorded a decrease in niuogen
percentage of V/immera ryegrass sown at high sowing rates. Other workers (e.g.
Henderson and Davies 1955; Harper and Gajic 1961) reported that variation in crude
protein contents of crops is possible because of leaf fall, shedding losses or the failure of
individual plants in high population to mature.
The responses in yield of cereal crops to nitrogen fertilizer depends on soil type
and available soil nitrogen (Moreira 1989) also seasonal rainfall. In cereal crops the use of
nitrogen fertilizer has increased dry matter yield, number of tillers, number of spikelets,
number of grain per spikelet and grain yield (Single 1964; Halse et al.1969; Cook l97l;
Langer and Liew 1973; Donald and Puckridge 1975). In our studies the growth of cereal
crops u/as restricted to the application of nitrogen fertilizer compared to legume species. In
Experiment I the legume component of the experiment produced higher dry matter yield
than cereals but when nitrogen fertilizer was applied the differences in the yield of these
crops disappeared. It was obvious that the cereals were nitrogen-deficient following
prolonged waterlogging of the soil : however, the vetches were well-nodulated and grew
drl
r
I
r
152
ill,i:
I
well.
Nitrogen fertilizer incr.eased mean dry matter yield of oats and vetch from 10 to
27Vo inExperiment 4 and ll to 4lEo in Experiment 5 during the season. The effect of
nitrogen fertilizer in both the experiments was greater in the early part of the season
compared to the latter part of the season.
The data reported in the literature by some workers (e.g. Kamparath et al.1958;
Wassermann et at. 1984; Jepsen 1986) suggest that the use of nitrogen fertilizer in
oats/peas or oats/vetch mixtures adversely affects the yield of legumes. In our studies
nitrogen fertilizer increased number of tillers, plant height and grain yield of oats.
However, the increase in grain yield seems to be due to the depressed growth of vetch in
nitrogen treared plots. Moreira (1989) reported that the effect of nitrogen fertilizer was
more obvious in oats and the increased proportion of vetch was having a buffering effect
on the dry matter yield especially in nitrogen-deficient conditions.
The dry matter yield obtained from the mixed stand of oats and vetch was greater
than from a pure stand of oats in the 1988 growing season in the later part of the season.
Similarly, the dry mauer yield obøined from the pure vetch stand was 297o lngher than the
dry matter yield of pure oats. In the later part of the season as vetch seed ratios in the
mixed stand increased, the mean dry matter yield of oaß and vetch increased. On the other
hand the pattern of dry matter production of oats and medic at various sowing mixture was
different in the later part of the season. The dry matter yield of medic reached its
maximum around 118 days after sowing and then declined. This was due to the early
maturity of the snail medic used in this study and probably some loss of dry residues at
time of sampling. Bowdler and Lowe (1930) reported that snail medic reached its
maximum growth in late winter, about a month earlier than Jemalong medic. The dry
mauer yield of oats/medic in mixed stands was higher than from the pure stand of oats 118
days after sowing. Similarly dry matter yield of the pure medic stand was 23Vo greater
than from pure stands of oats at this stage of glowth. Our results from this experiment
suggesr that the dry matter yield potential of oats is low when grown in low-fertility soil
tI
;
r
153
II
I
conditions. Of course, the potential productivity of oats is greatly increased with N
fertilizer. On the other hand, the dry matter potential of vetch is low compared to oats
when grown on fertile soil or when nitrogen fertilizer is applied. For example, in
Experiments 4 and 5 the dry matterpotential of oats was higher thanverch. The dry matter
yield of oats and vetch increased from 2l%o to 557o as oat seed in the sowing mixture
increased from 25 to 100 percent in the sowing mixture of oats and vetch compared to the
dry matter yield of vetch in the pure stand. Both experiments were on fallowed land of
good fertility.
In Experiment 5 the dry matter yield from the oats/vetch mixed stand and pure
oats was 627o and,727o higher than the dry matter yield from the pure stand of vetch.
Several workers (e.g. Hodgson 1956; Robinson 1960; Moreira 1989) reported that the
inclusion of vetch with oats in mixtures has potential to increase dry matter yield in cases
of low nitrogen inputs and deficient soil nitrogen conditions. Also mixtures of vetch with
cereals grown for forage production under dryland (rain-fed) farming and low nitrogen
inputs should include a high proportion of vetch to maximize forage yield and quality.
Apart from increasing the forage production another advantage of growing a mixture is that
they safeguard against a total crop loss in event of unfavourable conditions (Trenbath
1974). The results also suggest that a high proportion of legumes included in a mixture in
conditions of low soil nirogen is not only desirable to increase herbage yield or improve
quality of feed but also for maximising biological nitrogen fixation which is one of the
main arguments for including forage legumes in the crop rotation.
On the other hand a high dry matter yield of an oats/vetch mixture can only be
obtained with a higher proportion of oats in the sowing mixture in conjunction with
adequate nitrogen fertilizer. A further advantage of an oats/vetch mixed crop observed
during this study and reported previously in oatsfiegume mixed crops (Hodgson 1956;
Robinson 1960; Klebsadel 1969) is the physical support by oat plants preventing lodging
of the vetch plant. The height of vetch reported in this thesis was about O.92m in the
mixed stand compared to 0.58m in the pure stand of vetch. This improves light
penetration into the forage stand and thereby increases potential dry maner pnrduction.
154
Another argument for the use of the legume in association with a cereal as forage
crops is to increase levels of crude protein. The crude protein contents of oats is low
which may affect the growth of all classes of animals. Robinson (1969) reported that
mixtures of oats and peas, horsebean or vetch did not produce grcater forage or seed yields
than oats alone but their protein yield and percentages were higher. Furthermore Brundage
and Klebesadel (1970) reproted that crude protein percentage declined continuously in the
oat plant from2ÙVo initiatly to less than lÙVo at maturity. In our study the crude protein
percentage of oats 48 days after sowing was 36.5Vo and declined to 5.5 7o 185 days after
sowing. In contrast, the crude protein percentage of vetch was 34.97o at 48 days after
sowing and declined to 13.27o 185 days after sowing. At the stage of growth when
oats/vetch mixtures are usually harvested, a wide gap in percent protein existed between
the two species. Some workers (e.g. Hodgson 1956; Robinson 1960) stressed that the
higher protein level in legume herbage highlights the importance of a grass4egume mixed
forage at a conventional harvesting stage (eg haymaking), and hence the quality of the
mixed forage crop will be influenced by the proportion of legumes included in the mixture.
Though these thesis studies have made contributions to knowledge on the subject
of cereaUlegume mixtures as forage crops, much research remains to be done:
Firstly, the potential for maximizing yield and quality of green forage (and hay )
needs to be further examined by manipulating the combinations of oats and vetch in terms
of species and cultivars (which determine height, maturity and quality), sowing rates,
sowing mixtures, and also the potential for strategic use of nitrogen fertilizer.
Secondly, the potential for cereavvetch mixtures for maintaining and fattening
sheep and cattle needs to be examined under field conditions.
Fínally, research along both of the above lines needs to replicated in time and
space to generate a range of options for farmers and graziers to incorporate into their
farming systems.
5. APPENDICES
Tabte 5.1. Experiment 2; Mean density at different stages of growth of
oats, medic and vetch sown at various sowing rates.
transformed data: figures in oarenthesis are the means of orieinal data)
Sowing rates
(kg,/ha)
Plants/m2
(Days after sowing)
10145 73 r32
Oats
Medic
Vetch
4.86(M9) 4.67(302) 4.48(267) 4.46(183)
4.89(Mr) 4.76(344) 4.ss(2s7) 4.67(197)
4.74(377) 4.42(224) s.s4(238) 4.s8(169)
LSD (P=0 05) 0.10 0.24 n.s o.l7
Table 5.2. Experiment 2. The effects of sowing rates on mean density of
(oats + medic + vetch) at various stages of growth.
(I-og transformed data: flgures in parenthesis are the means of original data)
Sowing rates
(ke/ha)
Plants/m2
(Days after sowing)
45 73 101 t32
5 2.7s(rs) 2.65(1s) 2.2r(e) 2.83(15)
3.23(2s) 3.17(24) 3.20(2s) 3.36(29)
s.l3(173) 4.33(134) 4.t9(r28) s.06(166)
s.66(2e2) s.ss(z7t) s.84(3s4) s.s8(27s)
7.37(1603) 6.89(1006) 6.ss(7s3) 6.0r(429)
10
100
50
s00
LSD æ=0.05) 0.21 0.26 o.34 0.39
156
Table 5.3. Experiment 2. The effects of sowing rates on total mean yield
of (oats + medic + vetch) at various stages of growth.
(I-og transformed data: figures in parenthesis are the rneans of orieinal data)
Sowing rates
(ke/ha)
Yield (kgDlvllha)
(Days after sowing)
45 73 101 t32
1
5
r.71(5) 4.1s(68) 1437 5193
3.64(38) 4.97(166) rs97 6968
4.r3(&) s.s2(262) 1990 7536
s.20(1s7) 69r(1062) 2647 9188
s.49(274) 7.3r(1s32) 3190 9382
7.03(11s0) 7.96(2962) 36s9 9678
10
100
50
500
LSD æ=O.05) 0.37 o.29 551 tzffi
Table 5.4. Experiment 3. Total mean yietd of oats and vetch at various
stages of growth when sown às pure and mixed stands.
(Loe transformed data: figures in parenthesis are the means of original data)
Species Yield (kgDlvl/ha)
(Days after sowing)
62 90 11833 r47
Oats
Vetch
3.96(s6) 5.78(350) 7.07(r3r3) 8.19(3826) 8.36(4594)
3.74(48) s.3s(2s3) 7.16(LMs) 8.17(4184) 8.28(4s91)
LSD (P{.0s) n. s. 0.36 n. s. n.s. n. s.
157
Table 5.5. Experiment 3. Total mean yield of oats and medic at various
stages of growth when sown as pure and mixed stands'
(I-og transformed data: figures in parenthesis a¡e the means of original data)
Species Yield (kÐlvl/ha)
(Days after sowing)
33 62 90 118 t47
Oats
Medic
4.O7(64) s.8s(372) 7.18(1384) 8.12(3sSl) 8.s2(s2r6)
3.86(s4) s.2s(227) 7.r7(t4s4) 7.92(3149) 7.04(1ssl)
LSD (P=0.0s) 0.15 0.21 n.s. n.s. 0.2r
Table 5.6. Experiment 4. The effects of sowing rates and sowing ratios
on number of plants/m2 of oats and vetch.
(Square root transformed data: figures in parenthesis are the means of orieinal data)
Sowing ratios Sowing rates
100 20050
oats vetch oats vetch oats vetch
25
50
75
100
8.s(72) 5.3(28) e.2(8s) 7.1(s0) 11.s(134) 10.0(100)
s.6(s2) 7.6(s9) 11.7(13e) e.7(e7) 14.s(20e) 13.9(194)
11.3(12S) e.1(83) 14.s(210) 13.0(16e) 1S.e(361) 17 -2(297)
13.3(178) I 1.s(132) rs.s(242) r4.4(2O8) 2r.8(482) 20.7 (427)
Species x Sowins ratios x rates {< tl. {< LSD (P=0.05) = 1.1
158
Table 5.7. Experiment 4. Mean yield at various stages of growth of oats
and vetch sown as; pure stands and mixtures.
transformed data: figures in parenthesis a¡e the means of original data)
Sowing ratios
Oas:Verch 48
Yield (kgDlvllha)
(Days after sowing)
to476 13l 159
0:100 s.10(184) 6.7S(e61) 8.07(3289) 8.63(5799) 9.05(8686)
25:75 s.2s(2ls) 7.Os(rz3s) 8.44(4742) 9.04(8599) 9.2s(10483)
50:50 5.17(19s) 7.O7(1260) 8.4r(4617) 9.14(9499) 9.40(t2t37)
75:25 s.40(2sr) 7.18(t4r7) 8.47(4902) 9.25(10632) 9-4s(t2919)
100:0 s.24(229) 7.18(1394) 8.4s(47 40) 9.22(t024r) 950(t34s2)
LSD (P=0 05) o.L1 o.L2 0.10 o.L2 0.09
Tabte 5.8. Experiment 4. The effects of different sowing rates on mean
yield at various stages of growth of oats and vetch grown as pure
stands and mixtures.
transformed data: ln are the means ofrates
(ke/ha) (Days after sowing)
76 104 131 159
S
48
50
2AO
100
4.74(120) 6.72(869) 8.2s(3893) 8.e6(8131) e.30(1113s)
s.19(187) 7.01(11s5) 8.3s(442s) 9.08(9137) 9.36(11841)
5.77(33S) 7 .43(1736) 8.s0(s057) e.r3(es94) e.33(11631)
LSD 0.13 0.10 0.08 0.09 n.s.
159
Table 5.9. Experiment 4. The effects of nitrogen fertilizer on mean yietd
at various stages of growth of oats and vetch sown as pure
stands and mixture.
transformed data: ln are the means ofDays sowmg Nitrogen treatments (kg/ha) LSD
0 50
48 5.19(200) s.28(229) n.s.
76 6.94(1100) 7.r7(1407) 0.08
t04 8.29(4074) 8.4s(4842) 0.07
131 9.01(8426) 9.10(9482) 0.08
159 9.29(1 1005) 9.37( 12067\ 0.06
Table 5.10. Experiment 4. The effects of different sowing ratios on crude
protein yield of oats and vetch at various stages of growth
transformed data: 1n are the means ofSowing protern yield
(Days after sowing)
Oats:Verch 48 76 t3t 185
0:100
50:50
100:0
2.64(15.8) 4.70(120.r) 6.34(s94.0) 6.37(s97.0)
2.7s(r7.s) 4.6e(1r8.2) 6.35(s86.0) 6.22(509.0)
2.82(re.8) 4.60(106.s) 5.78(330.0) 5.81(337.0)
LSD (P= 0.0s) n. s. n.s. 0.14 0.11
160
Tabte 5.11. Experiment 4. The effects of different sowing rates on total
crude protein yield. of oats and vetch at various stages of growth
transformed data: a¡e the means ofrates (kglha) Crude (kg¡ha)
(Days after sowing)
ln
48 76 131 185
100
50
200
2.29(rO.3) 4.35(79.4\ 6.0s(,146.0) 6.13(480.0)
2.63(14.6) 4.60(104.4) 6.17(s06.0) 6.19(s09.0)
3.2s(28.2) s.0s(161.1\ 6.2s(ss8.0) 6.ß7(4s4.0)
LSD (P= 0.05) 0.19 0.16 0.14 n.s.
161
80e€¿Afi)v€.9
tu)
(fx)
500
4(X)
3U)
200
lfi)
-{---_|---¿a-
Oals
Vetch
Tolal
20
0100-0 25-15 50--50 7 5-25 0- l(x)
Sorvi rrg ratio (oat:vetch)Figure 5.1. Ex¡reritnelrf 3. Dry mnfler yield ()f oafs and vcfcltsorvn as prrrc nntl nlixed sfalrtls 33 days nffer sorving.
(Ú
€oÞf)v!c)
--Û-.r-
-!+
Oats
Vetch
Tolal
l(x)-0 25-1s 50-50 7 5-25 0- I (X)
Sowirrg ratio (ont:vetch)
Iìigure 5.2. lÌx¡rerintcnf 3. Dry nrnller yicltl of 0îls nll(l vclcltsolvrt Írs pure în(t nr¡xcd sla¡ltls 62 tlays affcr srlrving.
0
162
esàobo
J4
g,9
3UX)
20(x)
r000
-{---t--__{-
Oals
Vetch
Total
0I (n-0 25-7 5 -50--50 7 5-25 0- I (x)
Sorvirr g ratio (oat:vetch)
Figure 5.3. Iìxperintetrt 3. Dry llìîlfcr yieltl of oÍìls alrd l'cfchs()wn as pure and nrixe<l sfantls 90 days aftcr stlrvittg'
6ú
âbf)
J¿
'õC)
fJ(XX)
6fiX)
4(XX)
2fiX)
-{}-
-l---*-
Oats
Vetch
Total
0l(x)-0 25-7 5 50-50 7 5-25 0- l(x)
Sorving ratio (oat:vctclt)
I,-igure 5.4. Iixpcrilncrrt 3. Dry lllaltcr yieltl_0[ oîls illld vctcl¡solvn as pUre fln(l lll¡xctl stalttls I lll tlays affcr s(tlv¡llg.
163
(d€àâbn
J¿
'õc)
IüXX)
rì000
6(XX)
4fiX)
--fl----*--_----t-
Oals
Vetch
Tolal
20u)
0100-0 25-7s -50-50 7s-25 0- lu)
Sowing ralio (oat:vctch)
Figure 5.5. Experinrent 3. Dry nrâtler yielcl- of 0ats plus vctchsorvn as pure and nlixed stands 147 days after sorvittg.
164
80
€
^ ()o
bt)J4
õí.)
F40
l(x)
íx)
-|-*
Oats
Medic
Tolal
20
0I (Xl-O 25-7 5 -50-.50 7 5-25 0- 100
.Sorvi n g rît¡o (oíìt:lìle<Jic)
Figurc 5.6. Experinrelrt 3. l)ry nlaf ter yicld^ of oats Ρrd lned¡csorvn Írs prtre r¡n(l nl¡xecl stands 33 days after solv¡ng'
.s(x)
A 4(x)
àogl 3n)I.9
l(x)
-_ü-
---|-..#
Oals
Medic
Total
0
I (X)-0 25-7 5 .50-50 7 5-25 0- 100
.Sowing r¡tt io (oÍtt: tìrcdic)
Figurc 5.7. IÌxperirnerrt 3. l)ry lnâtler yieltl rlf (lîts alld llled¡csorvrr as pln'c arrtl ntixetl slnntls 62 tlnys aflcr sttrvittg.
165
30(x)
2(XX)
(É-É,
obf)
J¿
!c) __I-
--+-
Oals
Medic
Totalt000
lfi)-O 25-75 50-50 75-25 0-100
Sorving ratio (ort:rlcdic)
Figure 5.t1. Ex¡rerintctrt 3. Dry matter yield tlf oafs âll(l nrc<licsolv¡l as l)lrre a¡ldnlixed stands 90 clays after sorvittg.
8(XX)
6(XX)
4(X)0
2(XX)
*
-t--!-
0
e
ob,J
59.9 Oats
Medic
Tolal
0r (x)-0 25-7 5
SowiFigure 5.9. lìxperirrrcnt
50-50 1s-25 0- 100
ratio (oat:rììc(lic)Dry nrattcr yield of oîls and ¡ltctlic
llg3.
sou'n :rs pure anrl rnixed slnnds ll8 tlays afler sou'ing.
166
8000
6UX)
4(XX)
2(XX)
+{-
-f,-
Oals
Medic
Total(d
¿oòov!C)
0100-0 25-7 5 -50-50 7 5-25 0- 100
Sowing ratio (oât:nredic)
Figrrre 5.10. Experinrent 3. Dry matter yield of oafs and metlicsorvn as pure andmixed sfands 147 days after sowing.
167
ÊÞ.ec1
g' 20HãcJ
bcË
El0Io
U)
10
0
20
14
14
70 l0lI)nys after sorving
70 tOI
lhys nfter sorvirrg
Oals-velch
---O- o-1oo
50-50
_-_*- l oo-o
l2Í1 t97
l2ll t97
Figure 5.ll Soil lotal nrineral nilrogen (ppm) concenfrnti<ln atvarior¡s stages of nralurity in plols of oafs plus vetch sown as pureantl nrixetl staltds.
0
EÊo.ÉrL)bt)
bÉ<dt<c)ÉË
Eo
o(t',
0- l-5c:lrt
l-5--l0crn
o
Figure 5._12 Soil lotal rnineral nitrogcn (pprn) at various sfagesof nralurify al lu'o rle¡rfhs irr pklls of oãls piris vetch sorvlr as pilrcarrd nlixetl stantls.
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