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QUEENSLAND DEPARTMENT OF PRIMARY INDUSTRIES 0089004
D
LAND RESOURCES OF THE EINASLEIGH - ATHERTON DRY TROPICS
M. J. Grundy and N. J. Bryde Land Resources Branch
Q Department of Primary Industries Queensland Government,
Queensland Government Technical Report
This report is a scanned copy and some detail may be illegible or lost. Before acting on any
information, readers are strongly advised to ensure that numerals, percentages and details are correct.
This report is intended to provide information only on the subject under review. There are limitations
inherent in land resource studies, such as accuracy in relation to map scale and assumptions regarding
socio-economic factors for land evaluation. Before acting on the information conveyed in this report,
readers should ensure that they have received adequate professional information and advice specific to
their enquiry.
While all care has been taken in the preparation of this report neither the Queensland Government nor
its officers or staff accepts any responsibility for any loss or damage that may result from any
inaccuracy or omission in the information contained herein.
© State of Queensland 1989
For information about this report contact [email protected]
Queensland Department of Primary Industries Project Report QO89004
LAND RESOURCES OF THE E I N A S L E I G H - ATHERTON DRY TROPICS
M. J. Grundy and N. J. Bryde Land Resources Branch
Department of Primary Industries, Queensland Government Brisbane 1989
ISSN 0727-6281
AGDEX 524
This publication was prepared for Queensland Department of Primary Industries officers. It may be distributed to other interested individuals and organisations. Funds provided under the National Soil Conservation Program to partly fund this project are gratefully acknowledged.
© Queensland Government
Queensland Department of Primary Industries GPO Box 46 Brisbane 4001
iii
~NTENTS
LIST OF TABLES LIST OF FIGURES ABSTRACT
I.
.
INTRODUCTION 1.1 Background to the study 1.2 The study area 1.3 Previous resource studies
PHYSICAL RESOURCES 2.1 Climate 2.2 Geology and landform 2.3 Vegetation 2.4 Water resources
.
.
LAND RESOURCE SURVEY METHOD 3.1 Terminology
SOIL LANDSCAPE UNITS AND SOIL ASSOCIATIONS
.
.
LAND USE 5.1 Present land use 5.2 Limitations on agriculture
PRIORITY ORDER OF MAP SHEET AREAS
. CONCLUSIONS
ACKNOWLEDGEMENTS
REFERENCES
Page
iv
iv V
6 6 17 19 21
24 25
27
35 35 37
45
47
49
49
APPENDIX I Symbols used to derive soil association mapping codes.
APPENDIX II Attributes of Great Soil Groups (in alphabetical order).
APPENDIX III Collated soil chemical data from commercial enquiries in drier areas of the Einasleigh-Atherton dry tropics.
52
54
6O
i v
LIST OF TABLES
Table 2.1 Annual rainfall variability index (Vl) for a number of centres.
Table 2.2 Mean rainfall per rain day (mm) for a number of centres.
Table 2.3 Streamflow attributes for major watercourses.
Table 4.1 Soil landscape units and soil associations with major limitations.
Table 4.2 Land limitation factors used to assign land suitability classes.
Table 5.1 Agricultural management units - their limitations and potential.
Table 6.1 Areas of soils in each of the five Land Suitability Classes within I: I00 000 map sheet areas.
Page
11
16
22
28
33
38
46
Figure 1.1
Figure 1.2
Figure 2.1
Figure 2.2
Figure 2.3
Figure 2.4
Figure 2.5
Figure 5.1
LIST OF FIGURES
Dominant land suitability in Queensland and location of the study area (box).
Major geographical features.
Average annual rainfall.
The monthly median rainfall of six centres.
The Waite Index - ~-(r/e 0'') for five centres.
The probability of receiving varying amounts of rain over a four month period commencing on (a) November I, (b) December I and (c) January I for eleven centres.
Average monthly maximum and minimum temperatures for Herberton and Mt Surprise.
Cropped land (1985) in the Einasleigh- Atherton study area.
Page
2
10
12
17
36
ABSTRACT
An exploratory study was undertaken of the land resources of the Atherton and Einasleigh 1:250 000 map sheet areas west of Cairns. The result, an overview of 3.5m ha of the dry tropics, is an aid to the setting of priorities for more intensive resource assessment. The work was funded by the National Soil Conservation Program.
Twenty-two soil landscape units consisting of 87 soil associations were identified. Of these, 33 soil associations were considered suitable for rainfed summer grain production with few, slight or moderate limitations. They covered an area of 533 000 ha with 2 981 000 ha unsuitable. Of the suitable soils, soil associations dominated by red earths occupied 166 000 ha, non-calcic brown soils and red podzolic soils 70 500 ha, black earths and grey and brown clays 72 000 ha and various suitable soils on alluvium 46 000 ha.
The climate including rainfall which is of moderate reliability is discussed. Research and development needs and degradation hazards are identified. Priorities for further resource survey are assigned based on the twelve 1:100 000 map sheet areas found within the Einasleigh - Atherton dry tropics.
1 • IFfRODUCTION
1 . 1 B a e k ~ o u n d t o t h e s t u d y
Intensive agricultural development in the northern half of Queensland is presently confined to the coastal fringe and adjacent tableland areas• Yet there exists a large area of land in the far north with a significant annual rainfall (greater than 700 ram) which produces store cattle from unimproved pastures•
There has long been a perception that appreciable areas of this land have the potential for more intensive use and this was formally recognised in the 'Assessment of the Agricultural and Pastoral Potential of Queensland' (Weston et al. 1981). Sorghum, maize, and, by inference, similar crops were assessed as well adapted to some 1.3m hectares of the far north with soil type, climate and landform as the assessment criteria•
This assessment was based on small scale soils mapping (Isbell et al. 1968) with input from local officers of the Queensland Department of Primary Industries (QDPI). This data base was insufficient for providing advice on cropping reliability or assessing the potential for degradation• If more detailed resource information could be obtained prior to extensive development then the adoption of sustainable cropping systems could be encouraged on suitable soil types.
Consequently the QDPI sought and received Federal funding through the National Soil Conservation Program (NSCP) for a study into the land resources of the dry tropics• Dry tropics in this study were taken to be tropical areas with a pronounced dry season and consequently a limited growing season•
Much of this land has impediments to more intensive use other than those addressed in the Weston et al. (1981) study• These include:
• access to existing agricultural infrastructure; • type of land tenure; • source of experienced farmers; and • current economics of site.
These are essentially ephemeral criteria but are factors that determine which of the potential cropping areas first comes under development pressure.
The study area chosen was the Einasleigh and Atherton I: 250 000 map sheets which adjoin the established agricultural areas around Mareeba and Atherton and which include a large portion of the potentially arable land (Figure I• I)• These sheets cover some 3.5m ha including wet tropical areas outside the scope of the study• These wetter areas, however, were included in the mapping as detailed studies of the agricultural areas were available and could be incorporated without further work. The mapping of complete map sheet areas also has practical advantages•
The first stage of the project reported here was an overview of the area to identify the major land resources and enable an assessment of priorities for further more intensive work. The results of earlier
F ~ - ~ ~ ~ : : ~,~-,--~_---~-~
~ z ::~: - - _ ~ ~ ~ : i
~ . 7 ~ . ~ , - - ~ - ~ : ~ ~ ~ _~-~_=
. . . . . . .
Q U E E N S L A N D D E P A R T M E N T OF PR IMARY I N D U S T R I E S
A G R I C U L T U R E B R A N C H
Adapted from
DOMINANT LAND SUITABILITY By J. Harbison and E.J. Weston (1980)
D r a w n by M . B . C a r r o l l
R E F E R E N C E
LAND S U I T A B I L I T Y GROUPS
i :i .i!:i : :ii ~ A. P . . . . . . . t arable (crop).
• , ~ ' . ~ . ~ B. Arable wi th s tab ihz ing pasture C a i r n s rotat ion~ (crop . . . . . pasture).
. ~ C. Non -a rab le except for sown pasture ._ ::~ es labl ishment (sown pasture).
~:::i" D. Nat i ve past . . . . . d . . . . agr icu l tura l land.
- - ~ - - ~ , ~ - _ -
-~-~ ~ ~
~ ~ - ~ - - - ~ -<.__,~
- ~ ~
. . . . . ~ _ _ . - - ~ - ~ - ~ - - - . _ _ ~ ~, . . . . , ~ - , ~ - - ~ , . . ~ _ : ~ _ ~ , ~ . - - - _ _ . . . . . . . . ~ - ~ ~ \ ~ . ' . . \ _ _ ~ ~.-- ~ ~ - ' ~
. . . . . . . . . . . . ..,~ . . . . , __,~ ,~ . ~ ~ . - ~ - - ~ ~ - = _ - _ _ _ _ _ : _ ~ , ~ ;::.:.:~ : : . : : ~ , ~ , ~ % : ~ . . . . . . . . . . . . ~ . . . . ~ - - ~ ~_. • ~ . . . . . ~ . .'.~... " ~ - . ~ . _ ' ~ _ ~ : " ~'...~;,2~ ~ ~ - - ~ - - - - - - i - i ~ ~ - : ~ - ~ : : ~ : . ~ - -
~ L ~ _ • ~ ' - ~ i . i ~ i i i !~
_ _ . . . . . . . . . . .- ~ . . . . . . . . . . . . ,-~ i..
- - - - , .-~5 . . . . ;.~ -- -~ !- - - - - ~-:C/." ."
. . . . . . . . . . ~ ~__ --~ ~f.., _ _ --~ - - ~ . ~ . ~
- - ___~,
%
_ - . . . . . . . . . . . ~ ~ : : ~
o c k h a m p t o n
~y
P R E P A R E D BY T H E DIVIS ION OF L A N D U T I L I S A T I O N , D .P . I , , B R I S B A N E 1981.
Figure 1.1 Dominant land suitability in Queensland and location of the study area (box)
3
studies were reviewed and new field work commenced, the intensity of work being dependent on potential agricultural suitability.
1 . 2 The s t u d y a r e a
The major population centres, Mareeba, Atherton, Herberton and Ravenshoe (Figure 1.2) are concentrated in the intensive agricultural areas in the north-east of the study area. The more remote centres generally owe their existence to mining with important industries still centred around Greenvale (nickel), Kidston (gold), Mt Garnet (tin) and Chillagoe (formerly copper, now marble, limestone and tourism)• Mt Surprise and Einasleigh (formerly a copper mining town) are important rail heads. Portions of Mareeba, Herberton, Etheridge, Dalrymple and Atherton Shires are included in the area.
The area is connected to the coastal centres by four sealed highways in the north-east and two unsealed roads further south• The sealed Kennedy Highway connects Mareeba and Atherton with the south of the area through Mt Garnet and Greenvale and thence to Townsville• A sealed highway branches off this to go through Mt Surprise to the western and Gulf centres. Other important connecting roads run from Mareeba to Chillagoe and from the Kennedy Highway at the Lynd Junction to Hughenden south of the study area.
A rail line connects Cairns to Mareeba and branch lines run to Ravenshoe via Atherton and Herberton, to Chillagoe and to Forsayth via Mt Surprise and Einasleigh• Greenvale is connected by rail to Townsville.
Principal industries in the area include intensive agricultural, horticultural and dairy production in the north-east, beef cattle production over the whole area, mining (chiefly tin, gold and nickel) and tourism which is growing in importance.
I.S P r e v i o u s r e s o u r c e s t u d i e s
The whole of the study area has been mapped to soil associations in the Atlas of Australian Soils by Isbell et ai.(1968) at a scale of 1:2 000 000• This mapping has been the basis for a number of other reports looking in more detail at particular resource attributes or highlighting aspects of the original work.
• Isbell and Murtha (1970) published a soils map for the Burdekin-Townsville region which included the southern half of this study ar ea •
• Weston et al. (1981) based their broad assessment of agricultural and pastoral potential on the Atlas units relying for interpretation on local QDPI officers. The study also recommended that cropping in this area should include a pasture rotation•
• Kent and Shields (1984) in a more detailed study of the northern Burdekin region, used the 1970 Isbell and Murtha data as their soils base and collected additional information on slopes, geology, stoniness, land degradation and existing land use. This study included the Einasleigh
Maree
Mungan
~ e
\, Dimbulah
Athertom
T inaroo
Almaden,,]lk /)~'i/~ I_.~.,,x-,~Petford J l ~ (
Mount
?
,nlwa 7a''
#PT u l ly Fa l l s
--."Glen Ruth"
" - " ~ \ ' ~ S u r p r i s e ~ / - ~ " C a s h m e r , ~ , ,
:' Carpentaria ,~ Downs"
b..
¢'Conj
d "
M_ GR
"Valley of Lagoons"
SCALE 1 1 250000 KILOMETRES 10 0 1 0 20 30 40 50 60 70 80 90 100 K ILOMETRES
LEGEND
Atherton tableland ~ Properties •
Evelyn tableland ~ Railway i m i ! I i i
Figure 1.2 Major geographical features
I: 250 000 map sheet area and it resulted in maps of agricultural and pastoral potential. The Einasleigh map sheet area included those zones found to be climatically most suitable within the northern Burdekin region although relatively fe~ soils or landforms were physically suited to agricultural development and of these most were rated as being suitable only for intermittent or irregular seasonal cropping.
The established agricultural areas of Atherton and Mareeba in the Atherton map sheet area have been mapped in some detail. The Mareeba-Dimbulah Irrigation Area was mapped at very large scale and published at 1:50 000 scale by van Wijk (1975). These mapping data have since been collated and an agricultural land suitability map of the Irrigation Area prepared (Capelin 1985). The agricultural areas south to Ravenshoe have also been recently surveyed (M. Laffan unpublished data in preparation). Kent and Tanzer (1983) have published land resource and land suitability maps of Atherton Shire.
The areas further south and west have had less coverage. Apart from an unpublished 1:23 760 scale map of a small area north of Ravenshoe (C. van Wijk), there was a reconnaissance study of the Mt Garnet area (Skerman 1951) which more recently has been mapped into soil associations (Verster unpublished data). An agricultural land suitability map for Herberton Shire was also prepared during the early stages of the study reported here (Grundy and Reid 1986).
More recently the suitability of riparian lands for irrigation (Grundy and Bryde, 1988) has been assessed along the Millstream and the Herbert River and Blunder Creek as part of an investigation into the feasibility of d~mming some of the tributaries of the Herbert River to power new hydro-electricity stations.
Because of the interest in mining, the geology of the area received early study and much data are available. The current knowledge is summarised in Henderson and Stephenson (1980) and 1:250 000 scale mapping is available. More detailed mapping is currently being undertaken by the Queensland Department of Mines.
. PHYSICAL RESOURCES
2.1 Cl imate
The term 'dry tropics' has been used to distinguish the study area from the high rainfall areas adjacent to the east and to highlight the major climatic feature, the occurrence of an annual dry season• The term 'semiarid' is a frequently used alternative but has a range of meanings depending on context. One of the most widely accepted definitions is that of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) which considers that the semiarid tropics include wet-dry
tropical climates and tropical dry climates with 2 to 7 months of the year when rainfall exceeds potential evapotranspiration (Williams et al. 1985)• Such a definition includes virtually all of the study area.
Consequently, the supply of water is the chief constraint to biological activity in such a climatic zone and particularly where some form of agriculture is envisaged. The amount of water available to biological systems is determined by:
• amount of precipitation in a given time • reliability of that precipitation over time . amount lost through evaporation • distribution of rainfall over seasons . amount stored in soil or lakes • amount lost through run-off and percolation.
The last two factors are site specific and dependent on soil type and landform which are discussed in later sections•
2.1.1 Rainfall
Rainfall in the region occurs due to four main influences:
• the monsoonal trough from the north-west which affects the whole area
• trade winds from the north-east which affect the eastern part • an early winter anti-cyclonic front which brings light rain to the
east
• tropical cyclones which are sporadic but important•
The geographical distribution of rainfall is illustrated in Figure 2.1. Average annual rainfall is highest in the agricultural and dairying areas of the Atherton and Evelyn Tablelands on the eastern edge of the study area. To the north and more notably to the south and west there is a rapid decrease in annual rainfall which then levels off over most of the study area to range between 650 and 850 mm•
This decreasing gradient to the west is due to the abrupt effect of the coastal mountain barrier on the tropical air streams• The reduction
in average annual rainfall from Cairns to Mareeba or from Tully to Mt Garnet is about 35 mm/km (Gentilli 1971).
in u i i
914/0 845 M.~eet ~ "~I'"
• Chillagoe / ~ ~ 0~72
• 8 5 5 I I \\x%]
/°9141. C "~/ II
g \ " 117i2 "l \ Ravenshoe o'~
Mount Garriet" ~ \ %08 \ ~
o752 832o • -"-"~' 8°3 ~ o75~.
- - 8 0 0 Mount Surprise o787040~ ::239
• 761 ~ 8 0 0 759
/ Vo3 ~ , o o ~ \ • 650 ~ 700 ~ ' - e663
~ J,'o'o" ~ k x , x
• 622 700 Greenvale
\
Figure 2.1 Average annual rainfall
Annual distribution of rain has a more pronounced seasonality as annual rainfall decreases. Figure 2.2 compares the monthly median rainfall of six centres widely distributed over the study area. In the drier regions up to 91% of rainfall is on average concentrated in the November to April period. The winter rainfall component which allows winter cropping on stored soil moisture in southern and central Queensland grain growing areas is absent. The small, higher rainfall areas in the east, exemplified by Atherton in Figure 2.2 do have significant quantities of rain in the early part of winter. Such winter cropping as occurs there, however, (chiefly potatoes and navy beans) is irrigated and the winter rainfall consisting of low intensity rain and drizzle is often deleterious. In the drier areas, sufficient winter rainfall may occur in the eastern fringes (for example Gleneagle) to allow occasional opportunity fodder cropping. In the absence of irrigation, the 'growing season' is confined to the summer period throughout the study area.
2.1.2 Evaporation and 'effective rainfall'
There is a paucity of evaporation data over the study area with the only evaporation pans being at Parada and Southedge near Mareeba and at Walkamin. Temperature data are available from Mt Surprise and Herberton and have been used to derive evaporation according to the method of Linacre (1977) which estimates evaporation from temperature data and site specifications. The Linacre formula overestimates evaporation for Parada and Walkamin in the first half of the year and overall by 8.7% and 11.2% respectively. An overestimation is therefore likely at Mt Surprise and Herberton so that 'effective rainfall' would be underestimated using calculated values.
Unfortunately these derived and measured evaporation data do not adequately cover the range of environments. Much of the drier part of the study area with agricultural potential has an elevation of 600-700 m above sea level. Mareeba and Mt Surprise are approximately 400 m and Herberton 900 m. Walkamin is of similar elevation (590 m) but has a higher rainfall and may differ in temperature. Mt Surprise may represent the drier areas while the other four centres characterise part of the range of moisture regimes on the eastern edge.
A climatic index (Prescott 1949) was developed at the Waite Institute, Adelaide to assess the efficiency of monthly rainfall for biological production. Its final form was r/em where r is monthly rainfall, e evaporation from a free surface and m a constant varying from 0.67 to 0.8 (Prescott, 1949). Gentilli (1971), using the form r/e0.7, arrived at limiting values to characterise each month and an annual 'hydric index' (summation over 12 months of the Waite Index disregarding values greater than 4) to distinguish between climatic regions. In summary, monthly values of r/e0.7 less than 0.50 were regarded as arid and those above as humid. There were a number of limits within this broad grouping but the paucity of data for the study area does not justify their use.
In Figure 2.3, histograms illustrate the seasonal nature of 'effective' rainfall at all centres and the relative dryness of those areas typified by Mt Surprise. At least four 'humid' months occur at all of these centres during the summer months suggesting that, on average, moisture would be available for crop growth over the bulk of the study
A
E 300 E
200 I =
,- 100
g )
~ 0
GLEN EAGLE
J F M A M J J A S O N D
Months
ATHERTON
E 300
200 ._=
• - 100 ._~
" 10
0 J F M A M J J A S O N D
Months
E 300 E
D
200 C
,- 100
g )
0
C A R P E N T A R I A DOWNS
J F M A M J J A S O N D Months
A
E 300 E
200 C
,- 100
"10
~ 0
MT SURPRISE
J F M A M J J A S O N D
Months
MT GARNET
E 300 E
200 C
,- 1 0 0
~ 0 , , ~ J F M A M J J A S O N D
Months
E 30O E
m
200 C
• - 100 .m
0
CHILLAGOE
J F M A M J J A S O N D
Months
Figure 2.2 The monthly median rainfall of six centres
1 0
10.0
MT SURPRISE HERBERTON
ANNUAL HYDRIC ANNUAL HYDRIC
INDEX 16.1 INDEX 24.2
6.0
6.0
o o
4.0
2 0
0 ......... f I ~ i J F M A M J J A S O N D J F M A M J J A S O N D
Months Month8
PARADA WALK AMeN
ANNUAL }{YDRIC ANNUAL HYDRIC
INDEX 17.8 INDEX 21.3
c:>
4.0 .
J F M A M J J A S O N D J F M , S O
Months
SOU THEDGE
ANNt.JA L HYDR!C
INDEX 20.7
6.(]
o
J F M A IV J J A S O N D
Months
Months
Figure 2.3 The Waite Index (r/eO.7) for five centres
11
area. The s~med values of r/e 0"7 (Gentilli's hydric index) are included with each graph. The values lie within the 'forest range' except for Herberton which is on the margin of the ralnforest range (Gentilli 1971).
This accurately describes the Herberton area which has forest and rainforest in close proximity but the vegetation at Mt Surprise is predominantly woodland.
2.1.3 Rainfall variability and reliability.
Variability is as important an attribute of rainfall as its seasonality. Various indices have been used in Australia to describe variability.
In the Australian Year Book (1986) variability over the continent is mapped using the ratio of the 90-10 percentile range to the median. These data are presented for a nt~nber of centres in the study area (Table 2. I). With the exception of Greenvale in the far south of the study area, the values fall within the zone of moderate variability for Australia (0.75- 1.00) and are similar to the variability range found in the eastern Australian wheat belt.
Table 2.1 Annual rainfall variability index (VI) for a number of centres VI = 90 percentile-10 percentile. Year beginning December.
median
Centre Altitude Median rainfall Vl (m) Cram)
Herberton 899 1 123 0.75 Ravenshoe 914 1 174 0.77 Chillagoe 352 843 0.82 Petford 480 846 0.82 Mt Garnet 671 780 O. 83 Gleneagle 557 780 0.84 Glen Ruth 600 796 0.94 Gunnawarra 6 I0 755 0.97 Kidston 520 694 0.94 Dimbulah 407 743 0.99 Greenvale Station 427 591 I. 16
The coefficient of variation (standard deviation/mean annual rainfall %) reveals a similar pattern with values less than 30% in the humid north-east, less than 34% elsewhere in the north and less than 40% in the Einasleigh map sheet area. Both indices reveal a gradual increase in variability from the north to the south within the drier climatic region.
The percentile data published by the Bureau of Meteorology can be used to gauge the reliability of rainfall in particular situations. In Figure 2.4 the probability of receiving particular amounts of rain is plotted over four month periods beginning in November, December and January. The proportion of years that 300 and 700 mm of rain are received are highlighted; 300 mm being more than sufficient rain for the Waite Index for the four months to exceed 2. The 700 mm value would
RAVENSHOE
m100
~, 80 _
~ ~o
~ 40
o 2c
Rainfall (ram)
HERBERTON 10C ~ 100'
= -~
~ 60 "~ 60
~ , 40 ~ 40 >, ~,
20 ~ 20
o 1~o ' ~ o s~o ' ~o ' £ o Rainfall (ram)
GREENVALE DIMBULAH
m 10C::=: : --
~ 80
~ 60
~ 40
"6 20
1;0 300 5(~0 ' 700 ' 900 0 1 ()0 ' 300 ' 5(~0 ' 7(~0 ' 900 Rainfall(ram)
ATHERTON CSIRO 100":==== -- = T , ~ m 100'
o ~ 80 ~ 8o
60 "~ 60
~ 40
"6 20 "6 2o
°o 1'Oo ' 3~o ' 5,~o ' 4 0 ' ~ o o Rainfall (ram)
) 100 300 500 700 900 Rainfall (ram)
PETFORD
lOO
_~ 8o
"~ 6(?
~ 40
"6 2O
0
m lOO
§ 80
-~ 60
~ 4a
"6 2(?
._= 60
--. 40 { o 20
0 1;0 ' 3(~0 ' 5;0 ' 7(~0 ' 900 Rainfall (mm)
KIDSTON ~ lOO!
80
60
40
"6 2O
CHILLAGOE
100 300 500 700 900
100 300 ,500 700 900 Rainfall (ram)
Rainfall (ram)
GUNNAWARRA
12
1 O0 300 500 700 900 Rainfall (ram)
GLEN EAGLE
1~o ' 3do s~o ' 7do g6o Rainfall (ram)
I O 0
_~ 8c
6o
40
6 20
GLEN RUTH
1 ~ ' 3 ~ ' ~ o ' 700' ' go Ralnfall(mm)
Figure 2.2 (a) The probability of receiving varying amounts of rain over a four month period commencing on November I for eleven centres
13
100
. - 60
~ 40
o 20
GREENVALE
0 100 ' 3 ;0 ' 560 I 700 ' 900 Rainfall (ram)
100 (a
o
= 6 0
~ 40
o 20
0
100~
~ 80 = m = 60 m
4 0
"6 2 o
0
100
~ 80
= 60
o 20
%
HERBERTON
Rainfall (ram)
A:THE RTON CSIRO
100 300 500 700 900 Rainfall (ram)
RAVENSHOE
40 ' 36o ' 5& ' z~o ' 96o Rainfall (ram)
KIDSTON m I 0 0 ~
~ 8o o
"~ 60
® >,
"6 20
O 100 300 500 700 900 Rainfall (ram)
100
=
~ 6 0 m
~ 4 0
o 20
GLEN RUTH
,6o ' 3 6 o ' s ~ ' 40 ' 9 ~ o Rainfall (mm)
DIMBULAH
m 1 0 0 ~
80 ..g
60
~ 40
"6 2O
1;o ' 36o ' 5 ; 0 ' ; ' ;o ' 9;0 Rainfall (ram)
1 O0 m
m ~ 60 ¢ ._
o 20
o
100,
3 u ° 8o o
~ ~°
"6 2C
100 ...,....~ = i"
~ 8o o
~ 40
o 2(
100=~'=---: _- ~.
8 80
~ 40
"6 20
0
CHILLAGOE
100 300 500 700 900 Rainfall (ram)
GUNNAWARRA
100 300 500 700 900 Rainfall (ram)
PETFORD _ _
1,~o ' 3 ; 0 ' 5 ; 0 ' 7~o ' 9 ; 0 Rainfall (ram)
GLEN EAGLE . . . . . .
1;o ' 36o ' 5 ; 0 ' 76o ' 9;0 Rainfall (mm)
Figure 2.2 (b) The probabi]~ty of receiving varying amounts of rain over a four month period commencing on December I for eleven centres
DIMBULAH
100'
~ 80
~ 60 ._
~ ~o
"6 20
0
300 500 700 90O Rainfal l (ram)
0 100 300 500 700 900 Rainfal l (ram)
100'
8o o _
60
40
"~ 2o
G REENVALE
CHI L LAGOE
100 300 500 700 900
HERBERTON
100 300 500 700 900 Rainfal l (ram)
GUNNAWARRA
Rainfal l (ram)
ATHERTON CSIRO
100 , - - : - z :. = z = i ~ l
~ 8o
o 2C
o; 40 ' 3;0 ' 5~o 7~o ~o Rainfal l (ram)
100
c 6 0 m
~ 40
o 20
100
~ 80 =
~ 4 0
o 20
0
1 0 0
8o
"~ 6O
4O
~6 2O
o
RAVENSHOE - : _ - : : .. _ _ _
1(~0 ' 3 ;0 ' 500 ' 7(~0 ' 9~ ) Rainfal l (ram)
KIDSTEXN
100 300 500 700 900 Rainfal l (ram)
GLEN RUTH
--. . . . .
1 / w i i i i i i 3oo ~ 7~ 9~ Ra in fa l l (mm)
10£
6C
4C
o 2C
(a 100
~ 8o
" i 40
o 2C
100
_g 8o
~ 60
~ 40
o 20
10G%.... = : ..
_~ 8o
"~ 60
~ 40
"~ 20
0
1 0 0
_~ 80
"~ 60
~ 40
"6 2o
O0 100
1 4
100 3OO 500 7OO 9OO Rainfal l (ram)
PETFORD
,~o ' 3& ' s~o ' 7~o ' 96o Rainfa l l (ram)
GLEN EAGLE
100 300 500 700 900 Rainfal l (ram)
Figure 2.4 (c) The probability of receiving varying amounts of rain over a four month period commencing on January I for eleven centres
15
approximately increase the index by 4. So the 300 mm to 700 mm range covers a range of rainfall over the four month period from that barely adequate for crop growth to a surplus amount•
This analysis highlights many interesting features but two main trends are evident:
• Reliability is lowest in the south• Greenvale receives each quantity of rain less frequently over all periods• Kidston, the other southern centre included is markedly drier in the January to April period than all centres apart from Greenvale• Disregarding the higher rainfall centres of Herberton, Atherton and Ravenshoe, northern centres (Dimbulah, Chillagoe and Petford) receive more reliable rain than the southern centres with comparable annual average rainfall (Gunnawarra, Glen Ruth and Gleneagle). This assumes similar evaporation for these centres but reliable data are not available to enable 'effective rainfall' comparisons•
• For all centres more reliable rain falls over the December to March period than either the November to February or January to April periods• This suggests, in terms of rainfall reliability, December plantings are favoured•
2.1•4 Rainfall per rain day
Rainfall per rain day has been estimated by dividing monthly rainfall by the number of rain days per month and the results for a number of centres are tabulated (Table 2.2).
Rainfall per rain day is greatest during the summer months and relatively higher in the drier centres• Values for all centres are relatively high by Australian standards (Gentilli 1971) and indicate a potential for water erosion•
In the drier centres the high values in November and December are significant since under conventional cultivation systems, this intense rain would be falling on the bare, cultivated soil surface•
2•1•5 Water balance modelling
No attempt was made to model water relations for particular crops or soils in the current study. Subsequent work will enable the collection of detailed soil data which will then be used in water balance models with more detailed climatic data. This will thus allow a better assessment of soil suitability in this environment•
Kent and Shields (1984) used a grain sorghum/fallow water balance model to simulate cropping over the northern Burdekin region• Centres within the Einasleigh-Atherton dry tropics included Greenvale and Mt Surprise• A deep structured clay soil and a number of standard conditions were assumed• The simulation produced a frequency of crop success of five years out of six for both Greenvale and Mt Surprise and predicted mean yields of grain sorghum of 1577 kg/ha and 1822 kg/ha respectively•
Bateman and Wade (1986) compared the reliability of grain sorghum production using monthly water budgets for Mareeba, Mt Garnet and Mt
16
Table 2.2 Mean rainfall per rain day (mm) for a number of centres
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Raveas~hoe P 0 14.3 16.2 16.7 7.1 5.0 4.7 3.4 4.4 3.6 5.6 10.1 12.9
16.1 16.4 14.6 8.0 5.3 5.7 3.5 7.0 7.0 10.5 9.8 14.7
Gleneagle 16.5 16.3 15.5 5.8 6.5 6.5 9.0 6.5 9,0 10.5 14.8 13.3
Cu'eenwale 16.2 15.9 18.2 12.5 8.0 15.0 6.0 7.0 7.0 15.0 14.3 15.0
Chillagoe P O 15.2 16.8 14.4 9.0 12.0 12.0 4.0 0.0 4.0 6.5 10.8 15.4
Dimbulah 13.4 14.6 14.9 7.0 5.0 7.0 5.0 6.0 6.0 7.5 10.8 11.5
~It Garnet 16.4 15.3 14.3 7.2 4.0 6.7 5.5 4.0 3.0 8.5 11.4 16.4
P e t f o r d P 0 20.0 18.5 20.0 15.5 11.0 11.0 7.0 5.0 4.0 7.0 16.0 17.4
10.3
12.5
12.8
14.8
14.1
12.1
12.1
16.9
Surprise. They assumed a red earth storing 74 mm of plant available water and the same evaporation over all sites. Rainfall variability was estimated using the decile analysis. They concluded that mid-December sowings have a higher reliability and yield expectation and result in less runoff and soil loss.
Other aspects of rainfall such as the occurrence of long dry periods during the growing season are important in agricultural production. These require a more detailed analysis of daily rainfall and will be included in subsequent work when soil data will be available and water balance modelling possible.
2.1.6 Other climatic factors
There are insufficient temperature data available to fully characterise the area. The only long term data are from Herberton and Mt Surprise which represent the cool and warm extremes of the study area respectively. Average monthly temperatures for these centres are compared in Figure 2.5.
If these values are indicative of extremes in the area then the region is relatively mild for these latitudes. Temperatures in excess of 35oc are common at Mt Surprise in summer but 40oc is rarely exceeded. Frosts occur in most years at both centres but are more common and more severe on average at Herberton (5 days overall in June, July and August) than at Mt Surprise (2 days).
17
3O
J o~
20
E
10
0
/ MT SURPRISE H E R B E R T O N
, .-
4C
g
~ 2o
I--- lO
1 I I I - I I
Months Months
I-i Maximum temperature
• Min imum temperature
Figure 2.5 Average monthly maximum and minimum temperatures for Herberton and Mt Surprise
Cyclones are important climatic phenomena in the region. They usually occur between December and April but their occurrence and effects are unpredictable. Individual cyclones can have marked adverse or beneficial effects on agriculture through high winds, heavy rains and flooding. They contribute significantly to the rainfall variability particularly in the east of the area.
Hail rarely occurs in the region but has occasionally caused severe damage.
Data on wind are only available from Herberton and Mt Surprise. At Herberton the wind comes predominantly from the south-east for most of the year. A north-west component becomes important in December to March. The pattern is similar at ~bunt Surprise except that easterlies are as important as south-easterlies and the wind from the north-west becomes important a month earlier. Strong winds are rare at both centres.
2.2 Geology and landf'ona
The Great Dividing Range, in places barely perceptible, traverses the study area from the north-east corner in a south-south-west direction (Figure 1.2). Thus some 60% of the area is drained to the north-west by the Walsh, Tate, Lynd and Einasleigh Rivers which flow into the Mitchell and Gilbert Rivers and thence into the Gulf of Carpentaria. The remainder of the area is drained to the east into the Coral Sea by the Herbert, Burdekin and Barron Rivers.
18
The study area is in general elevated relative to surrounding lands and includes the area known historically as the Einasleigh Uplands. The highest point occurs just west of Herberton from which the land slopes gently away to the west, south and north. To the east the relatively narrow strip of the Atherton and Evelyn Tablelands adjoins the higher coastal range beyond the study area (White 1962, Best 1962).
Most of the area falls within three of the structural provinces collated and described by Henderson (1980). North of the Palmerville Fault line, which trends south east from below Chillagoe past Mt Garnet, is the Hodgkinson Province, a deformed sedimentary terrain which can be divided into two zones within the study area. The first is the Chillagoe Formation, a narrow region of tightly folded and faulted sediments such as chert and limestone (generally recrystallised to marble). East of this is the Hodgkinson Basin, a broad argillaceous sedimentary terrain grading to greenschist facies metamorphics.
The unusual and striking Chillagoe landform of rugged limestone tors and caves separated by gently undulating colluvial areas is now a major tourist attraction and a number of national parks have been declared. The Hodgkinson Basin is strongly undulating to hilly where exposed.
To the west of the Palmerville Fault is the Georgetown-Coen Province, a vast area of Precambrian basement inliers. The study area includes some of the Greenvale and Forsayth subprovinces which form part of the Georgetown Inlier. The latter occupies the south-western portion of the study area and contains tightly interfolded, multiply-deformed metasediments and metavolcanics. The grade of metamorphism is high and amphibolite facies and granulitic rocks prevail. Granitic intrusion occurred both before and after deformation. The Greenvale subprovince is a small area south-east of Einasleigh and just west of Greenvale. It consists of metamorphics of greenschist and amphibolite grade. The characteristic landform is gently undulating to undulating rises with frequent rock outcrops.
The Georgetown Inlier is bounded on the east by the Burdekin River Fault Zone. East of this and south of the Hodgkinson Province is the Broken River Province. It consists for the most part of deformed sediments in strongly undulating rises and hills.
The igneous activity cannot be conveniently grouped geographically and basic and acidic extrusions and intrusions have occurred sporadically over the study area. They do, however, form a major part of the surface geology and geomorphology.
Acid volcanic hills and mountains are widespread. In the north the Triassic Featherbed Range stands 300 m above the surrounding terrain and is deeply incised pink rhyolite and ignimbrite. It is of similar age to the Newcastle Range which lines the south-western edge of the study area. Other important acid volcanic ranges include the Sunday Creek Volcanics south of Ravenshoe and the Nanyeta Volcanics north-west of Mt Garnet.
The Herbert River Granite and the Almaden Granite which is a quartz-poor variant cover a large area stretching from north of Mungana to the north-eastern corner of the Einasleigh map sheet area. They are intruded by Elizabeth Creek Granite which extends from Herberton in the
19
east to the west of the study area. Precambrian granites occur in large areas in the south-west of the study area. These areas are mostly hilly but gently undulating rises occur in the north on the Almaden Granite.
There are minor areas of Precambrian and Palaeozoic ultrabasic and basic rocks throughout the study area (Best 1962, White 1962).
Cainozoic basalts occupy large portions of the study area (Stephenson et aS 1980). The McBride Basalt (olivine basalt) was extruded from 164 known vents and occupies a roughly circular area 80 km in diameter east of Mt Surprise. Flows commenced some 8 million years ago but that from the Kinrara crater may be as recent as 13 000 years. It is a gently sloping lava plain with small locally dissected areas.
The Atherton Basalt occupies a smaller area on the north-eastern edge of the study area and consists of olivine basalt and pyroclastics. It has a similar age range to the McBride Basalt and ranges from level plains to steep hills.
Tertiary lateritic plateaus (remnants of the late Tertiary Featherby Surface) occur in both well preserved and dissected landforms to the east and south of the McBride Basalt. Further north towards Mt Garnet, to the south of, and fringing the McBride Basalt, are extensive areas of Tertiary and Quaternary alluvial and colluvial deposits (Grimes 1980, Coventryet aS 1980). These are mostly level to gently undulating plains and rises.
2.3 Vegetation
The study area is large and diverse and this is reflected in the range of vegetation types and species. Much of it is uncleared woodland altered since European settlement only by the presence of domestic stock and a changed fire regime. Significant areas of the rainforest fringe in the north-east have been cleared for agriculture.
The vegetation of the Einasleigh map sheet area has been described by Perry and Lazarides (1964) and in more detail by Isbell and Murtha (1972). Most of their comments also apply to the Atherton map sheet area. In this discussion vegetation types are described using the structural formation classes of Walker and Hopkins (1984).
Closed forests originally covered the relatively small area of land stretching from just north of Atherton to some 10 km south of Ravenshoe. Atherton and Ravenshoe lie approximately on the western edge of this closed forest belt.
In the higher rainfall areas, rainforest occurs on a range of soil types but as rainfall decreases it is more commonly confined to the basaltic krasnozems. Virtually all of the basaltic areas have been cleared for agriculture and most of the remaining rainforest is on steeply sloping land.
Low vine forest or softwood scrub occurs sporadically on very stony areas on the McBride Basalt plateau. They are presumably fire-exclusion areas and in places where fire has been controlled seem to be advancing. The biggest expanse is the Forty-Mile Scrub National Park some 60 km south
20
west of Mt Garnet. A large number of species are present including Queensland bottle tree (Brachychiton rupestris) white cedar (Melia azedarach) and a number of Ficus species.
Eucalypt open forests adjoin the rainforest areas along the eastern edge of the study area. The largest communities occur on red earths and are a mixture of narrow-leaved ironbark (Eucalyptus drepa~ophylla and E. crebra) and a bloodwood (E. clarksoniana). ~mall areas of flooded gum (E. grandis) and forest red gum (E. tereticornis) occur in the north-east on a range of deep soil types.
Much of the remaining area is covered by woodland of various types. The well drained krasnozems and euchrozems support narrow-leaved ironbarks and variable-barked bloodwood (E. dichromophloia). In the western areas where podzolic soils and earths predominate on usually strongly undulating landforms, narrow-leaved ironbark is also widespread but associated species vary and can include Molloy red box (E. leptophleba), Cooktown ironwood (Erythrophleum chlorostachys), ghost gum (E. papuana) and variable-barked bloodwood. In similar eastern areas, the ironbark will be accompanied by carbeen (g. tessellaris), lemon scented gum (E. citriodora), bloodwood or swamp box (Lophostemon suaveolens).
Other communities are less regionally defined and occupy specific environmental niches. Thus rusty jacket (both sub-species of E. peltata) and silver-leaved ironbark (E. melanophloia) usually occur on well drained slopes with lithosols. Poplar gum (E. alba) occurs where drainage is impeded and the soil remains wet for long periods. Tea-tree (Melaleuca viridiflora) occurs in similar situations and Molloy red box is often a strongly dominant tree species on solodic soils and solodized solonetz.
The deep cracking clay soils tend to have very specific communities dependent on soil type. Black earths and grey clays are usually on treeless plains with blue grasses (Dichanthium species) and a range of other grasses and forbs. Grey and brown clays support open woodlands of mountain coolibah (E. orgadophila) and boree (Acacia tephrina) is found on strongly gilgaied grey clays. In places on the black earths and grey clays dense stands of black tea-tree (Melaleuca bracteata) occur. Such stands indicate the presence of raised water tables and the potential for saline groundwater rise if clearing takes place (QDPI 1987).
The terraces of major streams often support tall stands of forest red gum and carbeen. Long-leaved paper-bark (Melaleuca leucadendra) and river she-oak (Casuarina cunninghamiana) are common on banks and in stream beds.
Three major grass communities occur in the area; the blue grass grasslands on cracking clays, kangaroo grass (Themeda triandra) and black spear grass (Heteropogon contortus). The latter two communities occur in forest and woodland areas. There are also areas of Aristida species and blady grass (Imperata cylindrica vat. major).
Two plant species are of particular importance as weeds in the area. Heart-leaf poison bush (Gastrolobium gr~ndiflorum) is toxic to stock and where it occurs (usually on sandy earths) is fenced off to prevent stock losses. Rubber vine (Cryptostegia grandiflora) is a naturalised climbing shrub which has invaded stream frontages and other alluvial areas.
21
Although toxic to stock its chief economic effect is alienation of valuable grazing land, reduced access and mustering difficulties.
2 . ~ Water r e s o m - e e s
The study area includes a number of major streams. The Herbert and the Burdekin Rivers drain virtually all of the land east of the Great Dividing Range and eventually run into the Coral Sea. The Einasleigh, Lynd, Tate and Walsh Rivers and Elizabeth and Junction Creeks drain the land west of the Divide into the Mitchell and Gilbert Rivers and eventually into the Gulf of Carpentaria.
All major streams are monitored by the Queensland Water Resources Commission (QWRC) and their data covering most of the area are summarised in Table 2.3. The largest streams in terms of mean annual flow are the Herbert, Einasleigh and Walsh Rivers but the Herbert (and its major tributary The Millstream) and the Burdekin have by far the largest flows in the dry period. These facts have been recognised in the various proposals to dam streams for irrigation over many years. The study by Skerman (1951) was commissioned to investigate potential tobacco soils in the Mt Garnet area to be watered by a proposed dam near the confluence of The Millstream and Wild Rivers. The dam was later built instead on the Barron River to supply the Mareeba-Dimbulah Irrigation Area. Limited irrigation is practised at present on the riparian soils of the Herbert River and along the Walsh River as part of the Mareeba-Dimbulah Irrigation Area.
The major importance of most streams in the area is for stock water and, increasingly, as tourist and amenity areas. They hinder access and movement during the wet season and may flood.
Subsurface water has been less intensively investigated. Detailed information is available for the Atherton Tableland and adjacent areas due to the demand for water within the more intensive agricultural and urban areas. In the basalt areas south of Mareeba to Rocky Creek (about 22 km) supplies are good; up to 5 litres per second at an average depth of 50 m. An area of poor quality subsurface water occurs just west of Rocky Creek. Around Atherton flows of 30 litres per second at average depths of 70 m are common and provide the opportunity for widespread irrigation. In the Herberton and Ravenshoe districts flow rates average 2 litres per second.
Two other areas are known to produce appreciable quantities of sub-surface water though data are limited. In the Chillagoe limestone, flows of 30 to 40 litres per second are achieved at depths of 60 to 70 metres depth but the quality is suspect. Both artesian and sub-artesian waters are found in the McBride Basalt with moderate flow rates and good quality.
Table 2.3
22
Streamflow attributes for major watercourses
Site
Catchment Mean Maximum mean Minimum mean
area (k m2) annual monthly volume monthly volume
di scha rge (ML) (ML) (ML)
Blunder Creek
at Wooroora
Millstream at
Ravenshoe
Millstream at
Archers Creek
Wild River at
Silver Valley
Walsh River at
Nullinga
Walsh River at
Flatrock
Tate River at
Ootann
Lynd River at
Lyndbrook
Elizabeth Creek at
Mt Surprise
Elizabeth Creek at
Cambana
Copperfield River
at Narrawa
Einasleigh River at
Einasleigh
Herbert River at
Gleneagle
142 91 628 25 433 (Mar.)
90 61 378 16 462 (Mar.)
325 181 960 47 415 (Mar.)
585 204 658 69 849 (Mar.)
325 121 741 61 175 (Mar.)
2 770 856 092 278 962 (Mar.)
I 630 478 531 169 531 (Feb.)
1 215 193 016 68 555 (Feb.)
585 65 488 18 621 ( Feb. )
1 245 232 516 71 830 (Feb.)
3 050 492 648 199 252 (Jan.)
934 (Oct.)
878 (Oct.)
2 415 (oct . )
187 (Oct.)
212 (oct.)
930 (Oct.)
o (oct.)
7 (Oct.)
637 (Oct.)
633 (Sept.)
50 (Sept.)
8 315 1 247 565 410 758 (Jan.) 677 (Sept.)
5 290 1 121 804 383 032 (Mar.) 3 945 (oct.)
Table 2.3 continued
23
Catchment Site area (kin2]
Mean annual di scha rge (ML)
Maximum mean monthly volume
[ML)
Hi nimum mean monthly volume
(ML)
Rudd Creek at I 400
Gunnawarra
Cameron Creek at
8.7
Wyandotte Creek at
Wyandotte
350
I 190
Burdekin River at 1 190
Lake Lucy
Burdekin River at
Lucky Downs
6 125
Gray Creek at 930
Carters Mi II
McKinnons Creek at 1 270
Possum Pad
181 826
167 025
207 870
207 870
132 204
135 348
203 516
73 917 (Mar.)
50 347 [Mar.)
68 105 (Mar.)
68 105 [Mar.]
215 864 (Feb.)
39 431 (Feb.)
83 462 (Jan.)
233 (oct.)
915 (Oct.)
359 (Oct.)
359 (oct.)
4 239 (Oct.)
59 [Aug.]
0 (Jul . & Aug)
(Source: data supplied by QWRC)
3- LAID RESOURC~ SURVI~ METHOD
24
The survey area was divided into three parts• The first was the intensive agricultural areas of the Mareeba-Dimbulah Irrigation Area and the Atherton and Evelyn Tablelands. These had been mapped at scales larger than this study and no further field study was undertaken.
The second part was the dissected, hilly and mountainous areas. These were identified by air-photo interpretation and field work was limited to vehicular traverses to compare landforms and soils with the existing Atlas of Australian Soils mapping (Isbell et al. 1968) published at 1:2 000 000 scale and the 1:250 000 geological mapping (Best 1962, White 1962)• Worksheets of the Atlas mapping at 1:250 000 scale were avail abl e.
Both of the areas which received minimal field work had the existing large and small scale mapping re-interpreted into a common form - soil associations in soil landscape units.
The third part included those areas of possible agricultural potential. A reconnaissance survey involving air-photo interpretation, free field survey and the incorporation of existing geological and smaller scale land resource information was undertaken. Field work involved a total of 75 man days (2 people) during which 210 soil profiles and associated geomorphology and vegetation were described in detail. These descriptions are stored on computer file and are compatible with the terminology of McDonald et al. (1984). Numerous other undocumented field observations were used to alter boundaries on air-photos.
At each site the landform was rated for suitability for rainfed summer grain production by determining major limitations to production and thus placing the landform into one of five suitability classes. The classes were defined as follows:
• Class I Land suitable for rainfed production of summer grain crops with negligible limitations. This is highly productive land requiring only simple management practices to maintain economic production.
• Class 2 Land suitable for rainfed production of summer grain crops with minor limitations which either reduce production or require more than the simple management practicesl of class I land to maintain economic production•
• Class 3 Land suitable for rainfed production of summer grain crops with moderate limitations which either further lower production or require more than those management practices of class 2 land to maintain economic production. • Class 4 Marginal land which is presently considered unsuitable for rainfed production of summer grain crops due to severe limitations. The
I Where more than simple management practices are required, this may involve changes in land preparation, irrigation management, the addition of soil ameliorants and the use of additional measures to prevent land degradation.
25
precise effects of these limitations on the proposed land use are unknown. The use of this land is dependent upon either undertaking additional studies to determine its suitability for sustained production or reducing the effects of the limitations to achieve production.
. Class 5 Land which is unsuitable for rainfed production of summer grain crops due to extreme limitations that preclude its use.
Land is considered less suitable as the severity of limitations for a land use increase, reflecting either (a) reduced potential for production, and/or (b) increased inputs to achieve an acceptable level of production, and/or (c) increased inputs required to prevent land degradation. The first three classes are considered suitable for the specified land use as the benefits from using the land for that land use in the long term should outweigh the inputs required to initiate and maintain production. Decreasing land suitability within a region often reflects the need for increased inputs rather than decreased potential production. Class 4 is considered presently unsuitable and is used for marginal land where it is doubtful that the inputs required to achieve and maintain production outweigh the benefits in the long term. It is also used for land where reducing the effect of a limitation may allow it to be upgraded to a higher suitability class. Additional studies are needed to determine the feasibility of using this land.
Class 5 is considered unsuitable having limitations that in aggregate are so severe that the benefits would not justify the inputs required to initiate and maintain production in the long term. It would require a major change in economics, technology or management expertise before the land could be considered suitable for that land use. Some class 5 lands however, such as escarpments, will always remain unsuitable for agr icul tur e.
The study area was then mapped on air photos into soil landscape units (SLU) defined as recurring patterns of soils, landform and geology. Twenty-two SLU were recognised. These were further subdivided into soil associations consisting of major and associated soils. However, the very low intensity of the survey did not allow any estimate of the relative proportion of component soils. Eighty-seven soil associations were identified and mapped.
Soil associations in suitability classes 4 and 5 as well as swamps, watercourses, mining areas and bare rock were mapped as unsuitable for rainfed s~mer grain production and shaded red (see enclosed maps). The remainder are potentially suitable with varying levels of limitation to
cropping.
3- ~ Terminology
A number of codes and defined terms are used in this report to identify soil types or as a shorthand for concepts and/or procedures used. These are described here to assist in using the included information.
. -~-U (soll landscape unlt): A recurring pattern of soils, landform and geology.
26
• Soil associations: Each SLU is composed of two or more soil
associations consisting of a dominant soil and associated soils•
• Mapping codes: An example of a soil landscape is soils of dissected plateaus on basalt. The code for this is DB, the D referring to the landform (dissected plateaus) and the B to the geology of the substrate (basalt). The last two letters of each soil association mapping code derive from a similar pairing of letters• The symbol(s) preceding these letters refer to the dominant soil type. In the DB landscape, there are two dominant soil types, euchrozem and black earth, the symbols for which are E and BE respectively. Thus the full codes for these soil associations are EDB and BEDB which convey information about the soils, the landform and the geology. The various symbols used to derive these codes are listed in Appendix I.
• LSC (land suitability class): One of the five previously defined
classes of land based on the limitations inherent in the land for a particular purpose.
• AMO (agricultural mamagement unit): AMJs are groupings of soils with similar attributes and management requirements• They are used to simplify discussion of the limitations characteristic of soils and various aspects important in their agricultural use.
27
4. SOIL LANDSCAPE UNITS AND SOIL ASSOCIATIONS
Table 4. I is a listing of the SLU and soil associations with a summary of pertinent attributes. The relative occurrence of the major and associated soils is variable and because of the scale of the work could not be quantitatively estimated. In some cases, such as the RERT and SKLB units the nominated major soil may share the mapped unit more or less equally with some of the associated soils. In others, such as REPT and BYAN units one soil clearly dominates. The associated soils include those soils which occupy an appreciable portion of the unit and/or exert a modifying effect on overall agricultural suitability of the mapping unit. The list is not intended to be exhaustive.
The listing of principal profile forms (PPF) (Northcote 1979) is in order of dominance and indicates the variability within the dominant soil group to those familiar with this taxonomic system.
The land suitability classes (LSC) divide the soil associations into five groups based on suitability for rainfed agriculture. To assign soil associations to these classes, major land limitation factors were identified for each soil association, ranked from I to 5 and grouped. A composite rating was then subjectively obtained which constituted the LSC. The rating of limitations was based on the requirements of a rainfed summer grain crop. Other land uses may have resulted in a different suitability ranking for the area. The land limitation factors were those of Smith (unpublished data, Table 4.2).
The 22 SLUs are arranged in descending order of topographic relief; from mountains to alluvial areas. Consequently the first twelve SLUs (and the first 38 soil associations) whose common and salient landform attribute is steep slopes are LSC 5 and are not suitable for cropping either due to topography limiting machinery access and traffic or to erodibility due to excessive slopes. Where the major limitation is topography, soil erosion potential will also automatically be limiting in these SLUs and has not been included. Slope and hence erosion potential are also important attributes of the next 7 SLUs. The variation in inherent abilities of soils to resist erosion results in different classifications within the one SLU. Thus krasnozems and euchrozems with their strongly structured surfaces are less erodible on a given slope than red earths. Experience on the Atherton Tableland has demonstrated, however, that this structure deteriorates under intensive tillage over time.
Within the lower sloping groups and the alluvial and lava plains, slope is not an overriding attribute and the attributes of the soils rather than the landscape determine the final LSC with two exceptions. The first is rockiness, an important attribute on the lava plains. The second includes intake potential (the capacity to cause off-site seepage and salinisation) and outflow potential (the susceptibility to groundwater rise). These limitations occur with particular landscape positions and
geology.
The soil associations which occupy extensive areas and are potentially suitable for cropping include RERG, REPT, REPR, KPR, BELB, KLB, BEAL, GCAL and a range of the soils on non-basaltic alluvium. Of these, much of RERG
28
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33
and KLB lie within the intensively developed areas of the Mareeba-Dimbulah Irrigation Area and the Atherton Tableland respectively. A more detailed discussion of soil associations and their land use potential follows in Section 5.2. The attributes of the Great Soil Groups identified in the study are outlined in Appendix II.
Table 4.2 Land limitation factors used to assign land suitability classes
Land Limitation Components Comments Factor
Cl imate
Soil moisture
Soil wetness
Soil fertility
Salinity
Shallow rooting depth
Flooding incidence
Soil physical factors
Rockiness
tem perat ur e, relative humidity, frost, windspeed.
def ici ency, toxicity, f ixa ti on, disorders, dynamics.
moi st ur e range, crusting, hardsetting, hard pans, dispersive clays, coarse sel f-mul ching, adhesive soils.
Includes cl imatic attributes other than rainfall.
Limitation due to a limited plant available water capacity (PAWC).
Limitation due to drainage impedance.
Limitation due to plant's current or potential adverse nutritional status.
Limitation due to the presence of excess soluble salts.
Limitation due to restriction of root ramification for physical support.
Limitation associated with a flooding hazard.
Limitation due to adverse physical condition of the soil.
Limitation due to the presence of surface or subsurface coarse fragments (rock, stone cobble, gravel).
Table 4.2 continued.
34
Land limitation factor
Components Comments
Topography
Soil erodibility (water)
Soil erodibil ity (wind)
Intake -recharge potential
Outflow-discharge potential
slope, slope complexity, broken topography, gilgai.
Limitation due to the topography of the land as it affects access, machinery use etc.
Limitation due to erodibility of soil, erosivity of rain, slope and surface attributes.
Limitation due to soil surface attributes and wind speed.
L imitation due t o potential to cause off site seepage and salinisation.
Limitation due to potential for saline groundwater rise.
(Source: derived from Smith, unpublished data).
5 . LAUD USE
35
5. I P r e s e n t l a n d u s e
The present land use of the study area can be conveniently discussed according to three regions; the wet uplands, the Mareeba-Dimbulah Irrigation Area and the largest region, the dry tropics. Figure 5.1 identifies the areas where cropping occurs.
The wet uplands with an elevation in excess of 700m have an annual rainfall in excess of 1000~with some centres recording up to twice that amount. Hills and mountains in the region support extensive areas of closed forest or tall open forest much of which is in State Forest. The Atherton Basalt occupies a major part of the less hilly areas. Lower sloping land around Atherton and to the north supports intensive agriculture. The predominant enterprise has been a maize-peanut rotation but where irrigation is available through bores or streams, potatoes, navy beans, lucerne, pasture seed and a range of fruit trees are important crops. Dairying and beef cattle fattening on improved pastures are the main enterprises on the more undulating landforms. This region includes the Crater National Park.
The Mareeba-Dimbulah Irrigation Area extends from south of Mareeba northwards and to the west past Dimbulah. It was developed as an irrigation area in the 1950s with water from the Tinaroo Falls Dam. The principal crop is tobacco but the area is also one of the two major rice producing regions in Queensland. Other crops include maize,lucerne, coffee, pasture seed and tropical fruits, notably mangoes and lychees. The area includes a wide range of soil types on basaltic, metamorphic and granitic rocks. Tobacco is grown on the coarser-textured soils on granitic and metamorphic rocks, as tobacco grown on the krasnozems has an inferior leaf quality. Rice is grown on a grey clay - solodic soil complex which occupies a discrete area west of Mareeba.
The greater part of the study area and the focus of this report is the dry tropics. Annual rainfall is in general less than 1000 mm and in the driest areas is about 600 ram. The predominant enterprise is store cattle production with limited fattening. The cattle are almost exclusively Brahman-cross and for the most part graze unimproved pastures. There has been limited timber clearing. Cropping occupies a negligible proportion of the area particularly if it is realized that one grower south-west of Ravenshoe is producing sorghum on approximately 1200 ha and that this area is greater than the combined cropping area of the remainder of the dry tropics region. Rainfed crops have included sorghum, peanuts and maize. QDPI trials have indicated that large sections of the dry tropics are suitable for pasture improvement with Stylosanthes species and there has been an increase in interest in this option in recent years. National parks include the Forty-Mile Scrub 60 km south-west of Mt Garnet and a number of parks in the limestone caves area near Chillagoe and
Mungana.
36
M•EEBA:•"
ol Ravenshoe
Mount Garnet • %
o
, t
• Mount Surprise
eEinas le igh
• Kidston
• Greenvale
Figure 5. I Areas where cropping occurs in the Einasleigh-Atherton study
area
37
5.2 Limitations on ag~leulture
The data discussed in this section have been obtained through site descriptions and from existing information. It was not possible to obtain detailed chemical and physical analyses of soils for this survey. As a result, the discussions on management units which follow rely to some extent on limited local experience and more detailed experience elsewhere.
5.2.1 Agricultural Management Units
Agricultural management units (AMU) are soil associations or groups of soil associations with similar management requirements. Table 5.1 lists these A~Js and the characteristic limitations together with potential crop and pasture species and research and management considerations. Physical and some chemical limitations are deduced from site descriptions. Since more detailed characterisation was not possible at the reconnaissance scale of mapping, all known soil analyses for the drier regions where there has been limited cropping experience were collected and the data collated. These data are tabulated in Appendix III and were used together with the experience of local QDPI officers to arrive at nutritional limitations for the AMUs.
5.2.2 Topography
The hilly and mountainous SLUs are too steep for uses other than grazing. Other SLUs have topographic attributes which restrict the potential number of land uses.
The alluvial terraces (PAN, SCAN, BYAN and PSAN) adjacent to the Herbert River and other major streams have low slopes but in some areas are dissected by deep gullies and creeks running into the river. This reduces the individual areas of suitable soils and hinders access. The NCRM soil association is more frequently dissected by smaller gullies. Access is not as markedly affected but the size of discrete areas of land with low slopes is reduced. Some areas of RRG have a similar limitation.
5.2.3 Rockiness and stoniness
The presence of large quantities of surface and subsurface rock is characteristic of much of the hilly and mountainous areas particularly where (podzolic) lithosols are major soils. The rock limits pasture growth and reduces the effectiveness of pasture improvement using aerial seeding.
Rockiness is a more important limitation in the basaltic soils which, in the absence of rock, would have high suitability for rainfed agriculture. All of the McBride Basalt has been mapped as stony except where stone-free areas are known to occur or were strongly suspected. In the krasnozems and euchrozems this most frequently occurs downslope from gentle rises where colluvial flow has been d~mmed by a ridge. Detection of these areas by air photo interpretation has not been possible and reliable mapping of stone-free areas will require intensive field traversing. Special purpose infra-red photography may reduce the field survey requirement by discriminating between the heat reflectance of stone-free and stony areas.
38
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42
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43
Black earths and brown clays occur in slight open depressions in the basaltic plains. These soils are frequently stone-free or lightly covered with stones but those with appreciable quantities of stone are not easily separated using aerial photographs.
Within both the red and dark basaltic soils, stone-free soils or soils where the stone can be economically picked probably exist in sufficiently large areas to justify more intensive future investigation.
The suitability of the various soils on metamorphic rocks on low slopes is also reduced to a minor extent by the characteristic presence of quartz gravel in the profile. This most frequently occurs in the A horizon of non-calcic brown soils and could adversely affect emergence and increase machinery wear.
5.2.4 Soil variability and complexity
Soil variability could not be quantitatively estimated in this study. Some soil associations are, however, inherently more variable than others and consequently are more difficult to assess for overall suitability.
Soil complexes are associations of soils so intricately intermixed as to make mapping of individual soils impracticable. Two soil complexes were mapped. The grey clay - solodic soil complex (GSAN) occurs on non-basaltic alluvia at widespread sites in the study area. Typically, the land surface is gilgaied with the solodic soil or solodized solonetz occupying the mound or shelf and the grey clay the depression.
The Arriga complex in the Mareeba-Dimbulah Irrigation Area is of this type. Both soils are suitable for rice growing where irrigation is available due to the poor drainage attribute of the highly sodic subsoil. Sodic subsoils are probably characteristic of the other GSAN areas as well. The complexity and the gilgaied surface would make cultivation for other crops hazardous through exposure of sodic soil at the surface. The markedly different water characteristics of the two soils could result in variable times to maturity and consequent harvesting problems assuming that even germination could be achieved. In the undisturbed state, the two soils usually support different vegetation and in the dry season it is common to see green growth in the grey clay depressions and dry grass with large bare patches on the mounds.
The other complex mapped was a grey clay - red-brown earth (GRAL) which has isolated occurrence on basaltic alluvium. There is no history of cultivation on this complex but the apparent difference in moisture characteristics is sufficient to reduce the suitability to 3 (that is a moderate limitation) where the individual soils would rate 2. The complex usually occurs as linear gilgai with the red-brown earth on the elongate mound or shelf and the grey clay in the depression.
5.2.5 Flooding
Flooding, although a frequent occurrence in the area, seldom causes major damage. Some roads are invariably cut each year and particular areas have difficult or no vehicular access for up to two or three months in wetter years. Major floods where waters overtop stream banks and cover large areas of surrounding country are rare. This did occur, however, in
44
February 1986 in the Herbert River south of Mt Garnet as a result of the
heavy falls of rain brought by cyclone Winifred. Crops near the river were inundated and fences destroyed.
In general the risk of flooding is low (in the order of once in 15 years for the Herbert River) and has only been included as a significant limitation in low lying areas near streams (PSAN, some SCAN, WLB). Semi-permanent swamps have been included in the miscellaneous units.
5 • 2.6 Sal ini sa tion
Only one occurrence of salinity has been reported to officers of the QDPI. High levels of salt were measured in the soil where rice was grown on a grey clay - solodized solonetz complex in the Mareeba-Dimbulah Irrigation Area and were associated with seedling mortality. Salt may have been mobilised from the subsoil through the long periods of flood irrigation. Preliminary investigations suggest that the problem is not widespread. Elsewhere in the cropping areas, salting has not been observed.
The drier areas have had little clearing and no data are available on whether salt is present in appreciable amounts in the soils and rocks or whether there is potential for secondary salinisation following clearing. Many of the soils such as the red earths and non-calcic brown soils are highly permeable and appear to have the potential to act as intake areas for salt mobilisation in downslope areas. On the advice of local QDPI soil conservation officers, much of the recent clearing of red earths has avoided crests and footslopes and a recent investigation of these areas has revealed no apparent salting.
Scattered throughout the areas of black earths on the basaltic plains are stands of black tea-tree (~elaleuca br~teata). Clearing of such stands in central and southern Queensland has resulted in the rise of the watertable and consequent salinity. These areas have been rated as unsuitable for clearing.
6. FRIORITY ORM OF MAP SHEET AREAS
45
A major aim of this study was to assign priorities for more intensive survey of 1:100 000 map sheet areas and to assist in that process by identifying the area of suitable soils• The Atherton and Einasleigh I:250 000 map sheet areas include twelve I:100 000 map sheets which are outlined on the map accompanying this report• The area of soils in each of the five LSC for these map sheets is listed in Table 6.1. To assign priority the following factors (in addition to the area data) were con sidered.
• climatic suitability. Rainfall is higher and more reliable the further north and east the map sheet area occurs• The three most climatically suitable map sheet areas are Atherton, Ravenshoe and Cashmere in that order• Of the remaining map sheet areas, those on the Atherton 1:250 000 map sheet have more reliable rainfall than those further south•
• current development pressure. The Atherton map sheet area is already highly developed and includes the Mareeba-Dimbulah Irrigation Area and productive krasnozems and euchrozems of the Atherton and Evelyn Tablelands. The agricultural soils of the area are for the most part mapped to at least 1:100 000 scale and land suitability studies for Shire planning purposes have been completed• More detailed suitability studies incorporating unique mapping area data and computer-aided mapping and data collection would be useful but less important than the task of collecting data for the newly developing areas. Of the remaining map sheet areas the Ravenshoe map sheet is closer to established infrastructure and is experiencing most pressure for changes in land use. Consequently, resource information is not only required by agricultural advisors but also by shires and Government departments concerned with land• Moreover the feasibility of dsmming some of the tributaries of the Herbert River to power new hydro-electricity stations is being investigated• This may make more water available for riparian irrigation along the Millstream and Herbert Rivers and Blunder Creek, all within the Ravenshoe map sheet area. Minor development has occurred on the Cashmere map sheet area and, to an even lesser extent, on the Valley of Lagoons and St Ronans map sheet
areas.
• time required for survey. Time in the field will be reduced where there have been previous studies and where there is more hilly and mountainous country which would be surveyed less intensively• Among the map sheet areas with most suitable soils, Atherton and Ravenshoe would require less time than the Cashmere map sheet• The map sheet areas covering the McBride Basalt are likely to require unusually intensive field work due to the difficulty of assessing the presence of stone with conventional air photography•
• other factors• Consideration of the above factors leads to the conclusion that the highest priority for more intensive work within the Einasleigh-Atherton dry tropics is in the Ravenshoe map sheet area. If the Atherton map sheet is not considered there has also been most demand for resource information for Ravenshoe, access to agricultural infrastructure is greatest, there are more production and research data available, and there is the highest proportion of freehold land. Consequently, it is proposed that the next stage of work under the NSCP
46
dry tropics resource evaluation project will be a mapping of the soils and agricultural suitability of the Ravenshoe map sheet area at a scale of I : I00 000.
In the long term, mapping of the Cashmere map sheet should be considered. It has large areas of arable soils with a sufficiently reliable climate to suggest that cropping enterprises will eventually increase in number and scale.
Table 6.1 Areas of soils in each of the five Land Suitability Classes within I: I00 000 map sheet areas
Land Suitability Class Sheet area I 2 3 4 5
Conjuboy 47 680 38 320 86 430 119 170 Ravenshoe 5 830 21 100 55 890 68 930 141 360 Cashmere 49 940 32 040 87 860 122 400 Bullock Ck 10 990 64 350 17 290 200 510 Atherton 22 910 19 990 7 780 35 120 208 170 Valley of Lagoons 2 080 13 650 34 690 32 780 208 250 Einasleigh 34 990 1 410 25 590 229 800 Chillagoe 28 190 2 850 1 110 261 810 St Ronans 700 6 140 16 640 235 310 33 620 Mungana 7 050 3 290 283 900 Mt Surprise 500 3 710 3 090 102 280 183 030 Lyndbrook 1 620 5 160 17 050 269 580
7. CONCLUSIONS
47
The study identified the Ravenshoe and Cashmere 1:100 000 map sheet areas
as having the greatest potential for development for agriculture. The twelve 1:100 000 map sheet areas covered by the study were ranked in terms of the need for more intensive survey based on a range of factors
including:
• area of suitable soil associations, • climatic suitability, • current development pressure and existing data, • time required for survey.
The established agricultural areas around Mareeba and Atherton were not investigated in detail due to the availability of adequate resource and production data. The conclusions refer to the drier, less developed
areas.
Major conclusions:
• 533 000 ha or 15% of the area consists of soil associations suitable for rainfed simmer grain production• Virtually all of this area has minor
or moderate limitations.
• Water supply is the major limitation to agriculture.
• Summer rainfed cropping is likely to be moderately reliable in the
central and northern parts of the area.
• Climatic data need more intensive analysis. In the more intensive
studies, detailed climatic analyses will be incorporated with data on soil plant available water capacity (PAWC) so that water supply to the crop during the season can be estimated. Both are necessary, in conjunction with soil and plant attribute data to determine probabilities of success
of various cropping enterprises.
• Data are needed on the moisture and other physical attributes of the non-cracking soils of the area. Moisture studies will be incorporated in more intensive survey work. A greater understanding of the changes in physical attributes with tillage should result from QDPI trial work in the
area.
• Cropping systems to maximise water use and minimise degradation need to be established• The QDPI has established with NSCP funding a programme with red earths. Similar work on cracking clay soils with their high PAWC
and trafficability problems is warranted•
• More econemic data on rainfed cropping in the areas are required. Data on transport costs are needed so that the yield required over a
number of seasons for sustainable profitability can be determined. It is proposed that this data and economic analysis be included in subsequent
detailed work.
. There is a high potential for soil erosion in the early part of the wet season with conventional cultivation and cropping systems.
48
• The clearing of highly permeable soils with potential as intake areas has possible serious consequences in terms of future salinlsation. More detailed investigations are required.
49
ACKNCWLEDG~4ENTS
The authors wish to acknowledge the assistance provided by the following QDPI officers. Mr J. Kilpatrick and Dr E. Woods, Agriculture Branch, Mr G. East and Mr R. Shepherd, Soil Conservation Services Branch and Mr R. Bateman, formerly Soil Conservation Research Branch, for assistance during discussions and Mr R. McDonald and Mr K. Hughes for advice and assistance. Mr East was present during early field investigations.
The work was funded by the National Soil Conservation Program.
REFERENCES
Australian Bureau of Statistics (1986), Year Book Australia No. 70, Commonwealth of Australia, 35.
Bateman, R. J. and Wade, L. J. (1986), Prospects for stable productivity of grain sorghum in north Queensland, in M. A. Foale and R. G. Henzell (eds.) Proc. First Australian Sorghum Conference, Gatton, Feb. 1986
Best, J. G. (1962), Atherton, Queensland, I: 250 000 Geological Series. Bureau of Mineral Resources Australia, Explanatory Notes E/55-5.
Capelin, M. A. (1985), Land suitability of Mareeba Shire cropping areas, Queensland Department of Primary Industries Project Report Q085005.
Coventry, R. J. , Hopley, D. , Campbell, J. B., Douglas, I. , Harvey, N. , Kershaw, A. P., Oliver, J., Phipps, C. V. G. and Pye, K.(1986), The Quaternary of north eastern Australia, in R. A. Henderson and P. J. Stephenson (eds.) The Geology and Geophysics of Northeastern Australia, Geological Society of Australia, Queensland Division, Brisbane, 349-74.
Gentilli, J. (1971), Climates of Australia and New Zealand, ed., World Survey of Climatology Volume 13. Elsevier Publishing Company, Amsterdam, London, New York.
Grimes, K. G. (1980), The Tertiary geology of north Queensland, in R. A. Henderson and P. J. Stephenson (eds) The Geology and Geophysics of Northeastern Australia, Geological Society of Australia, Queensland Division, Brisbane, 329-47.
Grundy, M. J. and Reid, R.E. (1986), Agricultural land suitability of Herberton Shire, Queensland Department of Primary Industries Project Report Q086006.
Grundy, M. J. and Bryde, N. J. (1988), Upper Herbert River - Blunder Creek Irrigation Feasibility Study, Queensland Department of Primary Industries Project Report (in press).
5O
Henderson, R. A. (1980), Structural outline and summary geological history for north eastern Australia, in R. A. Henderson and P. J. Stephenson (eds.) The Geology and Geophysics of Northeastern Australia, Geological Society of Australia, Queensland Division, Brisbane, 1-26.
Henderson, R. A. and Stephenson, P. J. (1980), The Geology and Geophysics of Northeastern Australia, eds. Geological Society of Australia, Queensland Division, Brisbane.
Isbell, R. F. and Murtha, G. G. (1970), Burdekin-Townsville Region, Queensland, Soils, Resource Series, Department of National Development, Canberra.
Isbell, R. F. and Murtha, G. G. (1972), Burdekin-Townsville Region, Queensland, Vegetation, Resource Series, Department of National Development, Canberra.
Isbell, R. F., Webb, A. A. and Murtha, G. G. (1968), Atlas of Australian Soils. Sheet 7. Townsville - Normanton - Cooktown - Mitchell River - Torres Strait area. With explanatory data, CSIRO and Melbourne University Press, Melbourne.
Kent, D. J. and Shields, P. G. (1984), Land capability study of the northern Burdekin region, Queensland, Queensland Department of Primary Industries Land Resource Bulletin QV84002.
Kent, D. J. and Tanzer, J. M. (1983), Evaluation of agricultural land in Atherton Shire North Queensland, Division of Land Utilisation. Queensland Department of Primary Industries, Internal Report.
Linacre, E. J. (1977), A simple formula for estimating evaporation rates in various climates using temperature data alone. Agricultural Meteorology 18, 409-24.
McDonald, R. C., Isbell, R. F. Speight, J. G., Walker, J. and Hopkins, M. S. (1984), Australian soil and land survey handbook, Inkata Press, Mel bourne.
Northcote, K. H. (1979), A factual key for the recognition of Australian soils, Fourth edition, Glenside, South Australia, Rellim Technical Publications.
Perry, R. A. and Lazarides, M. (1964), Vegetation of the Leichhardt- Gilbert area, in General Report on Lands of the Leichhardt-Gilbert area, Queensland, 1953-54, Melbourne, CSIRO Land Research Series No. 11.
Prescott, J. A. (1949), A climatic index. Nature 157, 555.
QDPI (1987), Landscape, soil and water salinity. Proceedings of the Bundaberg Regional Salinity Workshop, Bundaberg April 1987, QDPI conference and Workshop series QC87001.
51
Skerman, P. J. (1951), Investigations, Ravenshoe-Mt Garnet area, in Seventh Annual Report of the Bureau of Investigation for the Year 1950.
Stephenson, P. J., Griffin, T. J. and Sutherland, F. L. (1980), Cainozoic volcanism in northeastern Australia, in R. A. Henderson and P. J. Stephenson (eds.) The Geology and Geophysics of North eastern Australia~ Geological Society of Australia, Queensland Division, Brisbane, 349-74.
van Wijk, C. (1975), Soils association map. Mareeba Dimbulah Irrigation Area, Queensland Department of Primary Industries, Agricultural Chemistry Branch.
Walker, J. and Hopkins, M. S. (1984), Vegetation, in R. C. McDonald, R. F. Isbell, J. G. Speight, J. Walker, and M. S. Hopkins, Australian soil and land survey field handbooks Inkata Press, Melbourne.
Weston, E. J., Harbison, J., Leslie, J. K., Rosenthal, K. M. and Mayer, R. J. (1981), Assessment of the agricultural and pastoral potential of Queenslandj Queensland Department of Primary Industries. Agriculture Branch Technical Report No. 27.
White, D. A. (1962), Einasleighj Queensland, 1:250 000 Geological Series. Bureau of Mineral Resources Australia, Explanatory Notes.
E/55-9 •
Williams, J., Day, K. J., Isbell, R. F. and Reddy, S. J. (1985), Soils and climate, in R. C. Muchow (ed.) Agro-research for the semi-arid tropics: north-west Australiaj University of Queensland Press, St. Lucia, Queensland, 31-92.
52
APPENDIX I
S~mbols used t o d e r i v e s o i l a s s o c i a t i o n mapping c o d e s
Soil types and codes Landforms and codes Geology and codes
BC - brown clay M - steep hills and
mountains
BE - black earth H - undulating and
rolling hills
BG - (bleached) grey earth D - dissected plateaus
BM - black earth (with
M. bracteata) S - undulating to
rolling rises
BY- (bleached) yellow
earth
U - undulating lava
plains
E - euchrozem
W~ - euchrozem, brown
variant
GB - grey-brown podzolic
soil
R - gently undulating
and undulating rises
P - gently undulating
plains and plateaus
L - lava plains
GC - grey clay A- alluvial plains
GR- grey clay - red-brown
earth complex
GS- grey clay - solodic
soil complex
HG - humic gley
K - krasnozem
NC - non-calcic brown soil
B - basalt
D - dolerite
G - granite and/ or granodiorite
L - limestone
(always prefixed by P)
L - basaltic
alluvium
(always
prefixed by A)
M - metamorphic
rocks
N - non-basaltic
alluvium
R - Tertiary lateritic
r emna nt s
S - sedimentary
rocks
T - Cainozoic
transported
sediments
V - acid volcanic
rocks
P - podzol
53
Appendix I continued.
FL- (podzolic) lithosol
PS - prairie soil
R - red podzolic soil
RE- red earth
SB- (stony) black earth
SC- solodic soil
SE- (stony) euchrozem
- soloth
~K- (stony) krasnozem
SR- (shallow) red podzolic soil
W - wiesenboden
X - xanthozem
T - yellow podzolic soil
TE - yellow earth
54
APPENDIX l I
A t t r i b a t e s o f G r e a t S o i l G r o u p s ( i n a l p h a b e t i c a l o r d e r )
B l a c k e a r t h s -
Black or brownish black, medium to heavy clay, granular surface overlying black, structured, alkaline, medium to heavy clay continuing to greater than 1.5 m or overlying weathered basalt, smectitic clay minerals or grey clay from I m. Calcium carbonate nodules may be present in the subsoil; moderately to imperfectly drained.
Black earths occur on basalt, granodiorite and alluvium derived from basalt usually on level to gently undulating landforms. Fertility is generally moderate to high but is variable and dependant on parent material. The largest occurrences in the study area are on the fringes of the McBride Basalt but important areas occur on the Einasleigh River and west of Greenvale. They have a high plant available water capacity (PAWC) and moderate to imperfect internal drainage. The major restriction for agriculture is the narrow range of optimum moisture for tillage and traffic. There may be slight gilgai and some areas are very stony.
( B l e a c h e d ) y e l l o w and g r e y e a r t h s -
Hard setting, dark to grey brown loamy sand to sandy loam over a deep (up to 0.2 m) bleached A 2 horizon over a grey to yellow, mottled, massive clay loam to medium clay becoming more mottled with depth. Many manganiferous segregations increasing beyond I m. Some variants have a loose surface.
These are poorly drained soils and they occur in the lowest part of the landscape or where underlying morphology causes drainage impedance. A large unit occurs south of Mt Garnet but elsewhere the soil is limited in area and occurs in association with the other earths. Agricultural suitability is restricted by the poor drainage and in many cases the large quantities of iron-manganese segregations in the profile.
E a e h r ~ z e m 8 a n d k r a s n o z ~ s -
Friable brown to dark reddish brown, clay loam to light clay grading to dark reddish brown to red, strongly structured, light to medium clay, either neutral (euchrozem) or acid (krasnozem) to greater than 1.5 m; well drained.
These soils are mostly found on basalt although euchrozems also occur on amphibolite, and krasnozems on Tertiary lateritic remnants and granite under rainforest. The major occurrences are on the Atherton and Evelyn Tablelands and the McBride Plateau. They have a moderate PAWC, are usually well structured in the surface and well drained. The more acidic forms tend to adsorb applied phosphorus and hence require large amounts but those occurring on the McBride Basalt (intergrades between euchrozems and krasnozems) have very high available phosphorus levels. Many of the latter are stony and would require stone picking before cultivation. Krasnozems and euchrozems are the basis of the peanut and grain cropping
55
of the Atherton Tableland and their physical attributes are suitable for a broad range of agricultural and horticultural uses.
E u c h r o z e m s , b r o w n variants -
As for euchrozems with the exception that the soil colour grades from dark brown in the surface to brown in the subsoil; neutral; well drained.
These soils occur on the McBride Basalt in slightly lower landscape positions than the redder soils and in the drier regions. They are frequently shallower than the euchrozems (although usually greater than I m deep) and sometimes have small iron-manganese nodules. They are frequently stony. Where stone-free, they have similar attributes to the krasnozems and euchrozems. This soil sometimes grades into a darker uniform light clay soil which resembles a chernozem.
G r e y a n d b r o w n clays -
Strong granular or platy, dark brown (brown clay) or grey to yellowish grey (grey clay) medium to heavy clay, over structured brown or grey medium to heavy clay usually extending beyond 1.5 m; moderately to poorly drained.
The grey clays are usually found in alluvial areas while brown clays are found on transported limestone sediments and are commonly in broad, shallow depressions on basaltic plains. They commonly occur in association with each other and black earths. Grey clays are also found in complexes with red-brown earths and solodic soils. Grey clays tend to be in lower positions in the landscape and may remain wetter for longer. They may have sodic subsoils.
G r e y - b r o u n podzolie soils -
Brown to yellow-brown subsoils but are otherwise similar to the red podzolic soils.
These soils occur in minor areas on the alluvial terraces of the major streams and are frequently intermixed with red podzolic soils.
H t m t c g l e y s -
Hardsetting, dark, sandy clay loam over gleyed and mottled, grey, neutral, clay loam. Poorly drained. Semi-permanent water table.
Only one occurrence was noted, south-west of Ravenshoe on basaltic alluvium. The poor drainage is the overriding limitation.
Non-enlcle b r o w n s o i l s -
Hardsetting, dark to red-brown sandy clay loam to clay loam over a red,
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strongly structured, neutral light medium to medium clay to 0.9 m+; well drained. Some sites have much quartz gravel in the surface.
These soils occur mostly on the more basic metamorphic rocks or dolerite. Small areas occur on granite or granodiorite. The main occurrence is in the south of the study area west of Greenvale and west of Mt Surprise. On slopes less than 3% these soils have high suitability for rainfed cropping. They have moderate PAWC and good drainage. Most of the country is undulating, however, with minor gullying so that intensive conservation practices would have to accompany clearing and cultivation.
(Podzolle) lltbosols-
Shallow, stony, loams or sands with variable A 2 horizon development (usually bleached) directly overlying weathered rock and otherwise little profile development.
(Podzolic) lithosols are widespread on steeply sloping land throughout the study area.
Podzol s -
Loose, brown sand or loamy sand grading to a pale or bleached sand over an acid yellow brown loamy sand. Very well drained.
Most podzols in the study area are rudimentary forms of the Great Soil Group. The largest areas occur on the hills and mountains. Loose stones and rock outcrops are common. Significant areas, however, occur on the alluvial terraces of some of the major streams notably the Herbert River. The low PAWC is the major limitation to rainfed agriculture.
Prairie soils -
Structured, brownish black, clay loam to light clay over neutral, brown to yellowish brown light clay to medium clay becoming more mottled with depth grading to weathered rock or alluvia by 0.5 m+; imperfectly to poorly drained.
Prairie soils occur sporadically and in small areas in the region usually on basalt or basaltic alluvia. The soils on basalt are frequently shallow (0.5 - 0.8 m) and rocky although stone-free deeper variants do occur. In the deep soils, PAWC is moderate and the soils are suitable for summer grain crops. The alluvial prairie soils are more commonly suitable for cultivation but are often located in areas which are prone to infrequent flooding.
Red-brmm earths -
Hardsetting, red-brown to brown, sandy clay loam to clay loam over a red brown to red, strongly structured medium to medium heavy clay becoming alkaline with depth to greater than 0.9 m; free calcium carbonate common at depth; moderately to well drained.
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These soils are of limited occurrence in the area and forms examined have had attributes tending towards the non-calcic brown soils at one extreme and to solodic soils at the other. The major occurrence is in a complex with grey clays north-east of the Lynd Junction. Moderate levels of sodium are likely to be present in the deep subsoils. These soils are hardsetting and in some cases have slightly impeded drainage. They have a moderate PAWC.
Red e a r t h s -
Hardsetting, dark reddish brown loamy sand to clay loam with a clear or gradual change to acid or neutral, massive or weakly structured, red clay loam to light medium clay to greater than 1.5 m; rarely mottled at depth; well drained.
Red earths are widespread in the study area and the soil landscapes they dominate occupy 31% of the total area of suitable soils. In the more steeply sloping country they are found on granitic and sedimentary rocks but they are more commonly present on level to undulating landforms on granite, recently transported sediments or on Tertiary lateritic remnants. The largest occurrences are in the north-east of the Einasleigh map sheet area, around Mt Garnet and in the Mareeba-Dimbulah Irrigation Area. Most of the cropping in the lower rainfall areas has been on these soils. They are deep, well drained soils which are easily worked when moist and trafficable over a broad range of moisture contents. The PAWC is low to moderate and the soils set hard when dry. Early experience suggests a high erosion potential. Research into conservation cropping on red earths is being undertaken south-west of Mt Garnet.
Red podzo l ie s o i l s -
Hardsetting, brown to dark reddish brown, sandy loam to clay loam with a paler A 2 horizon over reddish brown, acid, structured light to medium heavy clay to greater than 1.0 m; moderately drained.
These soils are widespread and occur on a range of slopes and parent materials. The most agriculturally important occur on gently undulating granite, in the Mareeba-Dimbulah Irrigation Area. Slope is almost invariably the major limitation although small areas of red podzolic soils occur on level alluvial landscapes. There may be minor drainage impedance and hardsetting surfaces. The PAWC is usually low to moderate.
S o l o t h s , s o l o d t e s o i l s a n d s o l o d i z e d s o l o n e t z -
Soloths - hardsetting, dark brown to yellow brown, sandy loam to sandy clay loam with a bleached A 2 horizon over blocky, yellowish brown, mottled, acid to neutral, light to medium heavy clay; poorly drained.
Solodlc soils - As for soloths but subsoil is alkaline and brown to greyish brown.
Solodized solonetz - As for solodic soil but the subsoil has columnar structure.
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These soils have sodic B horizons and most frequently occur on alluvial plains, although smaller areas are associated with granite and sedimentary rocks. Large areas occur south-east of Mt Garnet and west of
Mareeba on low slopes. The dispersive clay subsoil restricts root ramification and PAWC is low to very low. They are wet for long periods of the year. Cultivation may expose some of the sodic subsoil which disperses readily and forms surface crusts. These crusts reduce infiltration and restrict germination and emergence. Where irrigation is available, paddy rice can be grown on the level and very low sloping areas.
W i e s e n b o d e n -
Granular dark, light to heavy clay over dark, structured, alkaline light to heavy clay. Gleying of deeper subsoil. Surface may have manganiferous segregations and ochreous root channels. Poorly drained.
These soils occur in depressions in basaltic plains and have a permanent or semi-permanent watertable near the surface. Rare in the study area and of low agricultural suitability without drainage works.
X a n t h o z e m s -
Dark brown friable clay loam to light clay grading to yellowish brown, strongly structured, light to medium clay, mottled at depth. May contain many iron-manganese nodules. Imperfectly drained.
These soils usually form where drainage is restricted at depth on basalt but also occur on acid volcanic rocks under rainforest. The main occurrence is west of Ravenshoe. Major limitations to agriculture include soil wetness and acidity at depth. Many areas of xanthozems in the study area are also stony.
Y e l l o w e a r t h s -
Hardsetting, dark brown to yellowish brown sandy loam to clay loam grading to acid to neutral, massive, bright brown to yellow, mottled clay loam to light medium clay becoming more mottled with depth to greater than 1.5 m. Texture contrast variants are common in the region. Moderately to imperfectly drained.
Yellow earths occur in association with the other massive earths and are widespread. They occur where drainage is sufficiently restricted to cause reducing conditions for part of the year. Thus, although they have many attributes in common with red earths, they are not as well drained and are frequently shallower. The largest occurrence is on the Lucy Tableland south of 'Wairuna'. Limited experience with these soils suggests that they have similar agricultural potential to the red earths except for crops which are particularly sensitive to drainage impedance.
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][ellcw podzolle soils -
Hardsetting, dark brown, clay loam with a paler A 2 horizon over bright brown to yellowish brown, acid, structured, light to medium heavy clay usually mottled to greater than 1 m; moderately to poorly drained.
Yellow podzolic soils have sporadic but minor occurrence in the area and are frequently in association with red podzolic soils. They tend to be less well drained than the red podzolic soils and often have a sandier surface.
60
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