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Paul DoraiswamyE. Raymond Hunt, Jr.
Hydrology and Remote Sensing LabU.S. Department of AgricultureAgricultural Research Service
Beltsville, MD
Coping strategies with agrometeorological risks and uncertainties for water erosion, runoff and soil loss
V.R.K. MurthyAcharya N.G.Ranga Agricultural University
Rajendranagar, Hyderabad-500 030, India.
Workshop On Agrometerological Risk Management 25-27th Oct., 2006New Delhi, India
Outline
Background
Soil Management Strategies
Crop Management Strategies
Mechanical Control Strategies
Examples of Soil Erosion Studies
• Iowa, USA• Mali
Conclusions
The pressure of increasing world population demands for higher cropsyields from the finite area of productive agricultural lands.
Meeting the needs especially in developing countries through more intensive use of existing agricultural lands may increase erosion.
Expansion into more marginal lands will substantially increase erosion.
There is an urgent need to take preventive and control measures to mitigate the threat of erosion to global food security.
An estimated loss of about 6 million hectares annually is estimated as aresult of degradation by erosion and other causes (Pimental et al. 1993)
Water erosion, runoff and resulting soil loss Background
Three major kinds of water erosion can occur.
1. Sheet erosion results when thin layers or sheets of soil are worn away. Sheet erosion can occur on nearly level land or on sloping land.If muddy water is moving off a field, sheet erosion is occurring.
2. Rill erosion usually occurs on sloping land where small channelsare formed by running water. The signs of rill erosion can be
masked by normal tillage practices.
3. Gully erosion occurs when rills continue to wash away and become more severe. It is more likely on steeper slopes and cannot be smoothed by normal tillage practices.
Background
Development of these gullies is partly related to poor land-use practices, including plowing parallel to the sloperather than plowing along slope contours. Photo Credit: Dr. Dan Balteanu, Romanian Academy
Sheet Erosion
Background
Rill Erosion
Background
Collection of sheet erosion water into channels ( rills) that erode the bottom and side of the rill
Severe gully erosion, Credit Cranfield Univeristy
Gully erosion
Background
Increasing size of rills eventually lead to a gully or a channel too large for crossing by farm equipment.
Runoff occurs when rain falls faster than it can be absorbed into the soil. Runoff water carries soil particles into streams and rivers causing water pollution and sediment.
Background
The Three Gorges, Qutang, Wu and Xiling, along the Yangtze River
http://www.chinatoday.com.cn
Soil erosion is the process by which soil is moved. When soil is eroded, it may become pollution in the water or air. The eroding land loses fertility lowering crop production.
There are two basic classes of erosion.
A. Natural erosion over geological time scales has made beneficial changes in the earth, such as rounding off mountains and filling in valleys. The re-depositing of soil forms new, highly fertile areas, such as the Mississippi Delta in the U.S.
B. Accelerated erosion removes topsoil at an excessive rate - results from human activity on the land.
Background
Cultivated Land
Agronomic Management Soil Management Mechanical Methods
Mulching Crop Management
Conservation Tillage
ContourTillage
Ridging Tillage
Minimum Tillage and No-till
Terracing Waterways Structures
Natural Synthetic
High-densityplantings
Multiplecropping
Cover cropping
Croprotation
Strip-cropping
Coping Strategies
Soil conservation strategies for cultivated land (El-Swaifly et al, 1982)
1. Soil Management Strategies
Conservation Tillage Practices
Contour Tillage Ridge Tillage Minimum and No tillage
Coping Strategies
Contour farming in Northern Iowa
2. Agronomic Management Strategies
Organic Matter Green manureStraw residue
Crop ManagementCover cropsMultiple crops
Coping Strategies
3. Mechanical Control Strategies
TerracingWaterwaysStructures
Coping Strategies
These strategies are generally applied in developed countries –real need is for strategies for developing countries
Coping Strategies
Decision Support Systems for Soil and Carbon Management across the U.S. Corn Belt
P. C. Doraiswamy1 , E.R. Hunt1, C.S.T. Daughtry1, and J.L. Hatfield2
U.S. Department of Agriculture, ARS,
1 Hydrology and Remote Sensing Lab, Beltsville, MD2 National Soils Tilth Lab, Ames, IA
Examples of Soil Erosion Studies
MODIS Normalized Difference Vegetation Index (NDVI-250m), State of Iowa, May, 2002
Study Area Scale
Kilometers0 25 50 100
NDVI
Ames
Management Scenarios
• Spring no-till drill• Pre-plant sub surface
fertilizer @• Side dressing for corn• Corn residue shredded
just before soybean planting
• Fall mulch tiller• Pre-plant surface
fertilizer @
• Fall moldboard tillage• Pre-plant surface
fertilizer @
No TillMulchConventional
@ Total fertilizer amount remains same among different managements
• 30% mixing in the top 15 cms
• 95% mixing of residue in top 15 cms
• 10% mixing in the top 4 cms
Corn – Soybean Rotation
Study Area- Central Iowa
Landsat Classification
25 km
Crop Classification ISPADE & STATSGO Soils Map
% Organic Matter
Study Area in Central Iowa, USA
1 %
2 %
4 %
6 % SOC
Clarion
Nicollette
Webster
Okobogi
5 m
0
DEM
Soils in Iowa (Midwest, USA)
Erosion Productivity Index Computation model is a leading model with crop growth and yields for various crops and management practices.
http://www.brc.tamus.edu/epic/
CENTURY- A leading model for soil biogeochemical processes - Carbon, Nitrogen, Sulfur, Phosphorus.
http://www.cgd.ucar.edu/vemap/abstracts/CENTURY.html
The EPIC-Century Model developed in a collaboration between DOE Labs, Texas A & M University and USDA-ARS.
EPIC-Century Model
Assessment and Prediction of soil erosion, runoff and soil loss
SOC (20 cm)Clarion-Nicollet-Webster-Canisteo Soil Series
40
50
60
70
80
90
100
1970
1974
1978
1982
1986
1990
1994
1998
2002
2006
2010
2014
2018
2022
2026
2030
2034
2038
2042
2046
Year
SO
C(t/
ha)
No TillMulchConventional
Sand = 26%, Silt = 48%, Slope = 3%
SOC (20 cm)Canisteo-Nicollet-Clarion-Webster Soil Series
40
50
60
70
80
90
100
1970
1974
1978
1982
1986
1990
1994
1998
2002
2006
2010
2014
2018
2022
2026
2030
2034
2038
2042
2046
Year
SOC
(t/ha
)
No TillMulchConventional
Sand = 24%, Silt = 49%, Slope = 2%
Clarion-Nicollet-Webster-Canisteo Soil SeriesCanisteo-Nicollet-Clarion-Webster Soil Series
SOC
Mg
/ ha
Year Year
Clay= 27%, Sand= 24%Slope= 2%
Clay= 26%, Sand= 26%Slope= 3%
EPIC-Century simulations at sample sites (1995- 2020)
Accumulative Erosion - RUSLE
Eros
ion
Mg
/ ha
Accumulative Erosion - RUSLE
Eros
ion
Mg
/ ha
0.51
0.07
-0.25
Clarion-Nicollet-Webster-l Series
0.55
0.11
-0.21
Canisteo-Nicollet Clarion Series
0.47No-Till
0.14Mulch
-0.26Conventional
Downs-Tama-Fayette Series
Managements
SOC rate at Sample Study sites Mg/ha/yr)
Soil C sequestration simulations for 25 years (1995- 2020)
The EPIC-Century Model captured most of the complex biogeochemical processes for agricultural production.
Soil carbon sequestration reached stable levels after 25 years.
Erosion causes loss of soil, which affects the rate of carbonsequestration and crop productivity.
Crop residue management is one of the important factors to reduce soil erosion and increase carbon sequestration, especially over landscapes with considerable slope.
Summary
Paul Doraiswamy1, Gregory McCarty2, Raymond Hunt1 Mamadou Doumbia3,
1 Hydrology and Remote Sensing Lab, USDA/ARS, Beltsville, MD, USA2 Environmental Chemistry Laboratory, USDA/ARS, Beltsville, MD, USA
3 Laboratoire Sol-Eau-Plante, IER, Bamako, Mali
Modeling of Soil Erosion and Carbon Sequestration in Agricultural Lands of Mali
Rainfall Range:600-1200 mm
Madiama
Oumarbougou
FAO, 1999
August 24,2002
Ridge till conserves waterreduces erosion and increases
crop production in Mali
SPOT-HRG Image of Omarbougu RegionOctober 14, 2003
Multi-temporal Satellite ImageryOmarbougu, Mali
Quickbird, August 2, 2003
SPOT HRG, October 14, 2003
Landuse Classification 2003 Crop Season Omarbougu Study Area (8x8 km)
Improved Soil Management Practice- Contour Ridge Tillage System
Modeling Soil Erosion and Carbon Sequestration
• Reduce Surface Runoff• Reduce Soil Erosion• Increase Soil Moisture Recharge• Increase Available Soil Moisture • Reduce Crop Water Stress • Increased Crop Yields• Increased Biomass and Surface Residue • Increased Soil Carbon overtime
ClimateAnnual precipitationAnnual temperature
SoilsSampling depth
Bulk densityC, N, pH
BiomassCrop type
Crop rotationYields
ManagementLanduse history
Tillage, FertilizerResidue
Model Simulation Results
Crops yields for ridge till were higher for when seasonal rainfall was between 400-500mm. For conventional till, crops were under water stress during this period.
The soil C was higher for ridge till (0-20 cm) even at the same level of fertilizer application for both tillage systems under average seasonal rainfall conditions.
Erosion rates were lower for ridge till compared to conventional till when evaluated at a 3% slope in landscape.
Conventional Till
Ridge Till
Conventional Till
Ridge Till
Maize -3.73 18.15 16.11 58.39Sorghum -3.5 8.92 11.02 39.91Millet -1.85 16 6.29 34.61Cotton 0.9 21.25 6.22 39.44
MODEL Scenarios- Soil Carbon Sequestered 2003 –2027
CROP
Percent Change in Soil C (%)
Average fertilizer rate
Increased fertilizer rate
Percent change in Soil Carbon for the Study Region (0-20 cms)
Ridge + Residue + Increased Fertilizer
0.560.890.760.70
Ridge0.590.890.760.66
Conventional1.101.691.151.10SOC displaced by erosion (Mg/ha)
Ridge + Residue + Increased Fertilizer
2.06.36.06.5
Ridge5.812.611.510.7
Conventional20.736.525.324.5Erosion loss thickness (mm) a
Management scenario
SorghumMilletMaizeCottonParameter
Simulation : 2003-2027a Assuming a soil bulk density of 1.5 Mg/m3
Soil losses and SOC displaced over 25 years (0-20 cms)
CROP MANAGEMENT RUNOFF (mm)
PERCOLATION (mm)
ET (mm)
Cotton Conventional 51 3 694Ridge 33 12 704Ridge and Residue 26 21 701
Maize Conventional 56 5 688Ridge 33 11 703Ridge and Residue 27 22 699
Millet Conventional 65 6 676Ridge 41 17 689Ridge and Residue 25 20 701
Sorghum Conventional 70 7 670Ridge 34 26 687Ridge and Residue 36 28 683
Model prediction for a seasonal rainfall of 750 mm
Low-tech implements for crop and soil management
Rolf Derpch,http://www.rolf-derpsch.com/
Years
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
Mill
ion
hect
ares
0
2
4
6
8
10
12
14
16
Cerrados
Brazil
Area in Brazil cropped with grains
41 Mha
Cropping area under zero tillage system in BrazilCropping area under zero tillage system in Brazil
Highly Erodible Cropland
1997 – 103.5 million acres of highly erodible cropland
Conclusions
• Systems of erosion prevention strategies depend on landscape characteristics, soil properties, rainfall, and cropping practices. Therefore the optimum solution is site specific.
• Population growth is highest in developing countries, so agriculture will be intensified, potentially increasing erosion.
• More demonstration projects are needed to work with farmers to change practices for greater profit, greater soil quality, and prevention of erosion.
Thank You
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