Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil...
-
Upload
lily-hoffman -
Category
Documents
-
view
219 -
download
1
Transcript of Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil...
![Page 1: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/1.jpg)
Department of Soil Science,and
Centre for Soils & Ecosystem Function
Rothamsted Research, UK
Soil organic matter in the Rothamsted plots
David Powlson Andy Macdonald, Margaret Glendining,
Andy Whitmore, Kevin Coleman, Dudley Christian
![Page 2: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/2.jpg)
Is it OK to remove straw from arable land for use as bioenergy?
or …
No …. but …. Yes …. but …..
![Page 3: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/3.jpg)
A “perfect storm” :
Professor John Beddington FRSUK Government Chief Scientific Adviser
Climate change
Food security
Energy security
![Page 4: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/4.jpg)
Food security
Food production
Well functioning
soil
Soil organic matter
TransportAffordabilityPolicies, ….
Nutrients:• Recycling• Fertilizers
Management
![Page 5: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/5.jpg)
Ways of maintaining SOM in arable cropping
1. Ley-arable farming – i.e. intermittent pasture
2. Add crop residues
3. Add manures or other organic “wastes” …………………………………………………..
4. Minimise tillage• small effect, mainly redistribution• but useful to concentrate SOM near surface
5. Grow plants with larger root input (breeding)
6. Grow larger crops by using fertilizers (small effect)
7. Utilise “black carbon” or biochar?
![Page 6: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/6.jpg)
So appropriate to be cautious about residue
removalBut ….
• 50% of above-ground residues returned to soil in stubble + chaff (winter wheat, UK conditions)
• 1.9 t C/ha returned (stubble, chaff, roots, exudates) even when straw is removed (calculated from Broadbalk data)
![Page 7: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/7.jpg)
Soil CContent
Time
Increaseinputs (or slow down
decomposition)
Initial Equilibrium
Transition
FinalEquilibrium
Total SOM content changes between different equilibrium levels …. slowly
Long term experiments –
Valuable to quantify changes caused by different managements
In practice (non-experimental situations) –
Equilibrium rarely achieved;one management changesuperimposed on another
![Page 8: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/8.jpg)
Broadbalk continuous wheat experimentData modelled by RothC-26.3 (solid lines)
0
20
40
60
80
100
1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2020
Year
Organic C in soil(t C ha-1) Farmyard manure annually
Unmanured
NPK
Straw removed in all treatments
![Page 9: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/9.jpg)
Broadbalk- Winter wheat (continuous & rotation)Started 1843
![Page 10: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/10.jpg)
• Straw incorporated in one section since ????
• But this section also has higher clay content than rest of field
• Difficult to resolve effects
![Page 11: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/11.jpg)
Results from Roth and Woburn straw expts
![Page 12: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/12.jpg)
Even if changes in total SOC are small/slow, changes in specific fractions may be
occurring.
![Page 13: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/13.jpg)
So
il o
rgan
ic C
(%
)
0
1
burnt
incorporated
So
il to
tal N
(%
)
0.00
0.05
0.10
Bio
mas
s C
(kg
ha
-1)
0
50
100
150
200
250
300
350
400
Bio
mas
s N
(kg
ha-
1)
0
15
30
45
60
75
%C %C %N BC BC BN BN%N
Straw incorporation experiment, Denmark
(18 years, spring barley)
Powlson et al (1987) Soil Biology & Biochemistry 18, 159-164
No measurable effect on soil total C or N
40% increase in microbial biomass
![Page 14: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/14.jpg)
Can a small change in SOM have large effects on
soil properties?
![Page 15: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/15.jpg)
Draught Forces & Energy
Draught Force
Strain gauged frame(to measure draught forces)
Laser proximity sensors(depth & front furrow width)
Doppler radar sensor(forward speed)
![Page 16: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/16.jpg)
Broadbalk- Winter wheat (continuous & rotation)Started 1843
![Page 17: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/17.jpg)
0 m 5 0 m 1 0 0 m0 m
5 0 m
1 0 0 m
1 5 0 m
2 0 0 m
2 5 0 m
3 0 0 mS pecific
5 0
5 5
6 0
6 5
7 0
7 5
8 0
8 5
9 0
9 5
1 0 0
1 0 5
1 1 0
1 1 5
1 2 0
1 2 5
1 3 0
1 3 5
1 4 0
D raught, kPa
Continuous wheat
1
6
Continuous wheat
Sections
0
(straw incorporated)
Continuous wheat
2Rotation (2nd wheat)
3Rotation (3rd wheat)
4Rotation (forage m aize)
5Rotation (w inter oats)
Continuous wheat(restricted fungicides)
7Rotation (1st wheat)
8
(no herb icides)
9Continuous wheat
S trip N um bers2 0
1 9 1 7 1 5 1 3 1 1 0 9 0 7 0 5 2 . 2 0 1
1 8 1 6 1 4 1 2 1 0 0 8 0 6 0 3 2 . 1
Watts, Clark, Poulton, Powlson, Whitmore. Soil Use and Management 22,334-341 (2006)
Specific draught measurements; Broadbalk Experiment, Rothamsted
![Page 18: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/18.jpg)
Treatment SOC
%
Specific
draught, S
kPa
Nil 0.84 88
FYM 2.80 (↑233%) 77 (↓15%)
NPK 1.08 (↑29%) 75 (↓12%)
Watts, Clark, Poulton, Powlson, Whitmore. Soil Use and Management 22,334-341 (2006)
Broadbalk – SOC and specific draught
![Page 19: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/19.jpg)
“Labile C” – easily oxidisable – about 10% of total C (microbial biomass + metabolites)
• Increased by straw incorporation and N fertilizer application (larger yields, larger residue returns)
• “Labile C” – correlated with:
–Increased aggregate stability
–Increased water infiltration rate
Blair, Faulkner, Till, Poulton. Soil & Tillage Research 91, 30-38 (2006)
![Page 20: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/20.jpg)
Blair, Faulkner, Till, Poulton. Soil & Tillage Research 91, 30-38 (2006)
Rothamsted, Broadbalk Experiment
Water infiltration rate related to “labile C” – increased by straw and N fertilizer
Labile C Total C
![Page 21: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/21.jpg)
Labile C Total C
Blair, Faulkner, Till, Poulton. Soil & Tillage Research 91, 30-38 (2006)
Rothamsted, Broadbalk Experiment
Aggregate stability related to “labile C” – increased by straw and N fertilizer
![Page 22: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/22.jpg)
The benefits of SOM may not be directly proportional to
total SOC content
Arable 45t C ha-1
Managed grass80t C ha-1
Bare fallow40t C ha-1
ESRC transdisciplinary seminar, 20ESRC transdisciplinary seminar, 20thth April 2004 April 2004
![Page 23: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/23.jpg)
Concluding comments• Maintaining SOC content is vital for soil
functioning (“soil quality”)
• So unwise to regularly remove crop residues – one of few ways to add OM
• But considerable OM inputs from roots, stubble, chaff – these continue even if straw removed
• A suggestion – only remove straw every 2nd or 3rd year
![Page 24: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/24.jpg)
Concluding comments• Maintaining SOC is essential for soil functioning (“soil
quality”)– Crop production– Run-off, erosion
• So unwise to regularly remove crop residues – one of few ways to add OM to soil
• But considerable OM inputs from roots, stubble, chaff – these continue even if straw is removed
• A suggestion: only remove straw every 2nd or 3rd year – Region specific modelling can provide guidance– Implications for straw availability for biofuel
• But care – small SOC changes may have disproportionately large impacts on soil (physical) properties
![Page 25: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/25.jpg)
Sanguesa, Spain
200 GWhr/yrUses 160,000 t cereal straw per year
Electricity for 50,000 homes
![Page 26: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/26.jpg)
![Page 27: Department of Soil Science, and Centre for Soils & Ecosystem Function Rothamsted Research, UK Soil organic matter in the Rothamsted plots David Powlson.](https://reader036.fdocuments.net/reader036/viewer/2022081414/55143137550346dd488b5fd2/html5/thumbnails/27.jpg)
Putting a value on SOM