Coping strategies with agrometeorological risks and ... · Coping strategies with agrometeorological risks and uncertainties for water erosion, runoff and soil loss V.R.K. Murthy

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