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Root growth of barley, winter wheat, and beets - data from two soil types and two years Thorup-Kristensen and Berntsen AugOctDecFebAprJunAugOct Rooting depth (cm) barley wheat beets
Citation preview
Can deep roots remove the N
surplus?Main cropsCatch crops
Crop sequence
Kristian Thorup-KristensenDanish Institute of Agricultural SciencesPlantekongres 2006
Why look at root depth?
• Few field studies– very few related to N uptake
• Environmental regulation and evaluation– depth of rooting zone 100 cm?
• Much larger rooting depth frequently shown– concequences for the legislation?– can we use deep root growth to increase N
utilization?– use of main crops or catch crops
Root growth of barley, winter wheat, and beets- data from two soil types and two years
Thorup-Kristensen and Berntsen
0
50
100
150
200
250Aug Oct Dec Feb Apr Jun Aug Oct
Roo
ting
dept
h (c
m)
barleywheat
beets
Differences in crop rooting depth
PeaPotato
75 cm
Winter cerealsSugar beet
Winter rape
> 150 cm
> 250 cm
RyegrassClovers?Spring cerealsSeed grass ??
100 cm
Lucerne ??
White mustardFodder radish
ChicoryDyers voad
Winter rye / oats
0 10 20 30 40 50 60
0
100
200
0 10 20 30 40 50 60
0
100
200
- no coverRyegrassSalad burnettChicoryDyers voadD
epth
(cm
)
Root density Nitrate-N (kg/ha)
New undersown catch crops with deep rootsroot density and Nmin in November
0
50
100
150
200
250
300aug okt dec feb apr jun aug okt
Roo
ting
dept
h (c
m)
Fodder radish catch crop
Rooting depth of winter wheat, spring wheat and a fodder radish catch crop
- 3 years data
Spring wheat
Winter wheat
0 40 80 120 160
0
50
100
150
200
250
Dep
th (c
m)
Nmin (Kg N/ha pr. 50 cm soil layer)
Winter wheat - uncoveredCrucifer catch crop
247261 35
Nmin Nov. under wheat, catch crop or no cover
Nmin total to 250 cm:
Cereal catch crop 78
0 30 60 90
0
50
100
150
200
250
Dep
th (c
m)
Nmin (Kg N/ha pr. 50 cm soil layer)
Winter wheat - uncoveredCrucifer catch crop
144248109
Nmin April under wheat, catch crop or no cover
Nmin total to 250 cm:
0 30 60 90
0
50
100
150
200
250
Dep
th (c
m)
Nmin (Kg N/ha pr. 50 cm soil layer)
Winter wheatSpring wheat after uncoveredSpring wheat after crucifer catch crop
59145 38
Nmin after harvest of winter or spring wheat
Nmin total to 250 cm:
0 20 40 60 80 100 120
Winter wheat
Spring wheat
Spring wheat after crucifer catch crop
Spring wheat after cereal catch crop
Yield (dt/ha)
N Uptake (kg N/ha)
Yield and N uptake in winter or spring wheat
Konklussioner• The root zone othen deeper than 100 cm! • Significant differences among crops
– winter wheat has deeper roots than spring cereals– large differences among catch crops
• Deep roots can be used actively in rotations– after previous leaching of N– before shallow rooted crops
• Deep roots can be used to reduce N losses and N surplus
THANK YOU!
Kristian Thorup-KristensenDanish Institute of Agricultural SciencesPlantekongres 2006
Can deep roots remove the N surplus?