agricultural production and soil conservation
TRANSCRIPT
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Agricultural Production and Soil Conservation
“Cooking is a moral process, transferring raw matter from ‘nature’ to the satte of ‘culture’, and thereby taming and domesticating it… Food is therefore ‘civilized’ by cokking, not simply at the level of practice, but at the level of the imagination” (Lupton 1996. Food, the body and the self. Sage Publication, London).
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Irrigation vs. Non-Irrigation
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Two Examples• Xingjian Irrigation District in Jingyuan County,
Gansu Province, about 330 km northeast of Lanzhou. Lat. 36 50’ – 37 10’, Long. 104 33’ –105 18’. Annual precipitation 200 mm. Annual ET 2390 mm. Mean annual temperature 8.7 C.
• Without irrigation, annual per capital net income: 33 Yuan ($4) in 1984.
• With irrigation, the region produces cash and grain crops and the lifestyle and social settings of the region changed dramatically.Annual per capital net income reached 1050 Yuan ($132) in 1998.
• The irrigation project pumps the water 439 m high from the Yellow River and irrigates about 20,000 Ha of land.
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A Michigan Example
• Huron County, Michigan. A farmer and his son own 8,000 acres of cropland, operates a crop processing and storage plant, have about 40 employees (including seasonal farm workers). He collects classic cars and other antiques.
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Questions• What is agriculture? • Is it an attractive sector in the information
age?• How do social, economic, technological,
and physical factors affect agriculture?• What are current challenges facing
agricultural production?• Is there enough food to feed the world
population? • Why does hunger exist in the U.S. and the
rest of the world?
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• Soil Characteristics: texture, structure, wilting point, saturation, absorption
• Soil components: gravel, sand, silt, clay
• Soil erosion and sedimentation• Why soil erosion control?• Universal Soil Loss Equation• Management practices: terrace, crop
cover, buffer zone, tillage methods10/5/2006 20
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• Food demands = population * 2200 cal /day/capita
• World food demands = 6 billion * 2200 cal/day = 13,200 billion cal /day
• 1992-1994 average cereals production = 1,934 million metric tons per year= 322 kg/capita/yr= 2,000 cal/day/capita1 kg cereal contains 2,200 cal. Plus, vegetables, fruits, meats, milk, and eggs, etc. There is adequate amount of food for each person on the surface of the earth.
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• Global per capita food supplies for direct human consumption from cereals, roots, tubers, sugar (raw equivalent), vegetable oils, meat, milk, etc. 1969-1971 2,430 cal/day1988-1990 2,700 cal/day2010 2,860 cal/day
Source: Atkins and Bowler 2001. Food in Society. Arnold, London.
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Selected Agricultural Statistics
cropland/capita(1993)
Yields ofCereals(kg/ha)(1992-1994)
% of grainsfor animalfeed(1994)
fertilizer use(kg/ha)(1993)
World 0.26 2791 38 83
Europe 0.19 4099 59 116
Asia 0.14 2947 18 118
China 0.08 4482 23 261
N and C.America
0.61 4227 65 95
U.S.A. 0.73 5092 68 108
South America
0.33 2475 52 59
Africa 0.27 1160 15 21
Oceania 1.86 1748 54 41Source: World Resources: A Guide to the Global Environment, 1996-1997. O xford University Press, Oxford. 10/5/2006 24
Agricultural Production
• Climate• Soil• Crops• Livestock• Agricultural land- cropland and rangeland• Chemical inputs - fertilizers and pesticides• Seed- genetic engineering• Policies and subsidies
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Soil As A Base for Crop Production
• Solar energy• Water• Nutrients• Oxygen• Soil provides water, nutrients,
oxygen, and a base to plant growth
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Soil Definition• Unconsolidated material on the
surface of the earth that has been subjected to and influenced by the genetic and environmental factors of parent material, climate, organisms, and topography, all acting over a period of time. (Foth, 1990. Fundamentals of Soil Science, 8th Edition). 10/5/2006 28
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Factors Affecting Soil Formations• Climate: breakup of rocks into smaller
pieces by physical weathering or chemical weathering.
• Type of Parent Material: granite, sandstone, limestone, or shale.– Glacial Transport: glaciers movement.Water Transport: soil erosion.Deposition of sediment along the river shore forms alluvial soil.Wind Transport: wind erosion. Loess : wind blown material
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Factors Affecting Soil Formations
• Living Organisms: bacterial, insects, and animals, etc.
• Topography: flat soil, slope soil.
• Time
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The Characteristics of Soil• Texture: the size and shape of the
individual particles and their composition. e.g. gravel, sand, silt, and clay.
• Gravel: greater than 2 mm• Sand: coarse sand 1-0.5 mm, medium
sand 0.5-0.25 mm, fine sand 0.25-0.10 mm, very fine sand 0.10-0.05 mm
• Silt: 0.05-0.002 mm in diameter• Clay: particles <0.002 mm
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• Loam: mixture of heavy and light soil materials in: sand 30-50%; silt: 30-50%; and clay, 0-20%.
• Soil Structure: the arrangement or grouping of a soil's primary particles into aggregates.
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• Adsorption: the process of attaching something to soil particles.
• Leaching: the process of removing something from soil particles.
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The Composition of Soil
Organic Matter: humusMineral Nutrients: N, P, K, and
other trace elements.Gas: O2MoistureOrganisms
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• Saturation: the pore spaces filled completely with water.
• Field capacity: the soil retains all possible water against gravity.
• Wilting point: the only moisture left in the soil is in the form of a thin film and unavailable to plants. 10/5/2006 40
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The Soil Profile: a cross-sectional view of the soil layers.
• Topsoil: much nutrient available.• Subsoil: a zone of accumulation that
receives and stores soluble salts and organic matter that are leached down from the topsoil.
• C Horizon: weathered parent material.
• D Horizon: unweathered parent material (bedrock).
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Soil ClassificationClassification of soil groups
based on • the parent material,• horizon pattern, • texture, and• chemical content.
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Soil Conservation
• Why? • Urbanization• Soil Erosion• Pollution • Increasing Costs
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• Soil erosion: the removal of soil particles either by wind or water from their original places.
• Sediment: soil particles suspended in water.
• Sedimentation: deposition of sediments in the bottom of water bodies.
• The dust bowl of 1934-193810/5/2006 50
• Water erosion takes place in 382 million acres of the cropland in the U.S. in 1992 at the rate of 3.1 tons per acre and wind erosion at the rate of 2.4 t/acre (Kellogg et al. 1994. Highlights from the 1992 National Resources Inventory, J. of Soil and Water Conservation).
• Annually, about 1 billion metric tons of sediment enter the U.S. rivers and causes the off-site damage of $6 billion.
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Impacts of Soil Erosion• Loss of nutrients and reduced fertility• Reduced crop yield and income• Contamination of water resources• Reduced engineering projects• Damage to the fishery and wildlife
habitat• Increased costs to navigation and
recreation• Altered watershed hydrology and
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Factors Affecting Soil Erosion
• Precipitation• Soil• Crop• Topography (slope)• Management
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Erosion Control
• Crop Reserve Program • Vegetation• Contour Farming• Strip Farming• Crop Residue• Conservation Tillage
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The Universal Soil Loss Equation
• A = R* K*LS*C*P• A=annual soil loss (tons/acre/year)• R=rainfall index • K=erodibility of soil• L=length of slope• S=steepness of slope• C=cover type (grass, corn, soybean,
forest)• P=support practice (contour farming, etc.)
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)065.0sin56.4sin41.65()6.72
( 2 ++= θθmLLS
LS factor need to be computed: Example:S=4% slope, L=150 ft slope length, slope angle θ=2.3 degree, m=0.4
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Slope Length
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•• methods:methods:
–– automaticautomatic
–– manualmanual
•• factors:factors:
––precipitation precipitation
–– water level water level
–– flow velocityflow velocity
–– sand sand sedimentssediments
Hydrological process Hydrological process observationobservation
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Land use, runoff and sedimentLand use, runoff and sediment
Forestland(sea backthern+Simon poplar, ),shrub land 1(sapling sea backthern ), shrub land 2 (sea backthern)
sediment runoffsediment runoff ：：farmland> farmland> Chinese pineChinese pine >grassland>grassland
runoffrunoff：： farmlandfarmland > > Chinese pineChinese pine > grassland> grassland. .
Forestland, shrub land 1, shrub land 2 varied little
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5
10
15
20
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流失
泥沙
量（
t/ha
）
林地 灌丛1 农地 荒地 油松 灌丛2
0
200
400
600
800
1000
1200
径流
量（
L）
林地 灌丛1 农地 荒地 油松 灌丛2
Research Center for Eco-Environmental Sciences, CAS
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Buffer zone
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Buffer zone
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Crop residue
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Wind break
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Grass waterway
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Fruitful trip10/5/2006 80
Ridges
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A WINDOWS-BASED GIS-AGNPS INTERFACE
Chansheng He, Department of Geography, Western Michigan University, Kalamazoo, MI 49008; ChanganShi, ESRI, Inc., Redlands, CA 92373; and Bryan P. Agosti, The Mannik & Smith Group Inc., Maumee, OH 43537.
Remote Sensing Databases
GIS
SimulationModels
Research &Management
Figure 1. Integration of GIS, remote sensing, and simulation models in support of environmental research and management.
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QP SP St t
t t=
−+
( . ).
0 20 8
2
AGNPS (Version 5.0) is a single storm-event based simulation model for evaluating surface runoff, sediment and nutrient transport from agricultural watersheds [Young et al. 1989; USDA Agricultural Research Service 1995]. The model includes three basic components: hydrology, erosion and sediment, and nutrients (N and P). The hydrologic component calculates overland runoff and peak flow rate based on the SCS (Soil Conservation Service) curve number equation (Eq. 1).
Where Q is the overland runoff (inches), Pt is the total rainfall from a storm (inches), and St is the retention factor calculated by Eq. 2.
(1)
AGNPS MODEL
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Q A CS RO LWpA= −3 79 25 40 7 0 16 0 903 0 190 017
. ( / . ). . ( . ) ..
Where A is the drainage area in km2, CS is the channel slope in m/km, RO is the runoff volume in mm, and LW is the watershed length-width ratio.
S =1000CNt − 10
Where CN is the SCS Curve Number, which is related to soil and land use factors.
Peak runoff rate (Qp in m3/s) is computed by Eq.3:
(2)
(3)
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Y=R*K*LS*C*P*Slope Shape Factor
Where Y is the computed average soil loss per unit area, expressed in ton/ha; R is the rainfall and runoff factor and is the number of rainfall erosion index (EI) plus a factor for runoff from snowmelt or applied water; K is the inherent erodibility of a particular soil; L is the slope-length factor, S is the slope-steepness factor; C is the cover and management factor; P is the support practice factor; and slope shape factor represents the effect of slope shape on soil erosion [Young et al. 1989].
Upland erosion is computed based on the Universal Soil Loss Equation(USLE):
(4)
OutputVisualizer
StatisticalAnalyzer
Figure 2. The flowchart of ArcView nonpoint source modeling (AVNPSM) interface
Land Use Simulator
Input FileProcessor
ParameterGenerator
AGNPSUtility
Soil Land coverDEMHydrographyPrecipitationManagement
Databases
ModelExecutor
THE STRUCTURE OF THE AVNPSM INTERFACE
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• AGNPS Utility. This module allows a user to create a FISHNET (file name for dividing the study watershed into grid cells based on the watershed boundary database) and associated database file. The user can also edit and correct flow direction using this module.
• Parameter Generator. A pull-down menu is developed to generate the required 22 input parameters.
• Input File Processing. Once all the 22 parameters are generated, the user can use this module to produce an input file for AGNPS model.
• Model Executor. AGNPS model is run either within Windows or in the simulated DOS model. 10/5/2006 88
• Output Visualizer. The simulated AGNPS results of hydrology, sediment, and nutrients can be viewed either in tabular form or in map format.
• Statistical Analyzer. Many current GIS packages have limited statistical capabilities. The AVNPSM interface adds ANOVA (analysis of variance) to the ArcView and enables a user to examine the relationships of land use/cover and simulated results of hydrology, sediment, and nutrients.
• Land Use Simulator. This module allows a user to specify land use change scenario(s) in a subbasin or specific area based on the FISHNET and land use/cover files and evaluate the hydrologic impact of this change to the downstream area.
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Parameter Generator
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An Application Example
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Table 1. Comparison of the simulated (by the AGNPS model) and observed (by U.S. G.S.) peak flow rates from a single storm event in the Dowagiac River Watershed
Peak Runoff Rate (ft3/sec) Storm Event Antecedent Moisture Condition Simulated Observed
Difference (%)
June 8, 1980, 1.72" Dry 726 811 -10.5
Apr.29, 1981, 2.96" Dry 1638 1020 60.6
Sept.30, 1986. 1.88" Average 830 1030 –19.4
Nov.28, 1990, 2.89" Average 1579 1440 9.7 *Due to lack of the hourly rainfall data, the 24-hour rainfall amount is derived from the daily observation of rainfall data by multiplying an adjustment factor of 1.13 (Sorrell and Hamilton 1990).
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ADVANTAGES OF THE AVNPSM
• User friendliness• Easy modification• Reduced redundancy• Improved flexibility• Enhanced statistical function
LIMITATIONS OF THE AVNPSM
• Execution of the AGNPS has to be done in a simulated DOS environment.
• More robust statistical functions are needed to improve the analysis capability of the interface.
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Distribution of the AVNPSM Interface
The Chinese Academy of Sciences Institute of Geographical Sciences and NaturalResources Research
The CAS GuangZhou Institute of Earth ChemistryEnvironment et Grandes Cultures, FranceFlorida State UniversityGallo Vineyards, Inc., Healdsburg, California. Michigan State UniversityMontana State UniversityNew South Wales Environmental Protection Agency, AustraliaOlsson Associates, Phoenix, Arizona and Lincoln, NebraskaQueensland University of Technology, Australia Sugar Industry Research Institute, Reduit, Mauritius. The South Carolina Department of Health and Environmental Control-Bureau of WaterSoutheast Missouri State UniversityUniversity of Ankara, Ankara, TurkeyThe University of ArkansasThe University of Illinois at Urbana-Champaign, The University of South Carolina, The University of Wisconsin-Eau Claire Universidad Austral de Chile.The U.S. Geological Survey Water Resources Division
Have received 45 requests from 12 countries, including:
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Challenges in Agricultural Production
• Unpredictable weathers• Fluctuating market prices• Increasing cost of machinery
and chemicals
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• Stringent environmental regulationsThe Federal Agriculture Improvement and Reform Act of 1996 (farm bill) -conservation provisions: wetlands, habitat, environmental quality, forest, etc.The Clean Water Act - nonpoint source pollution, soil erosion, animal feeding operations, etc.Food Quality Protection Act (protecting children from pesticide residues)
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Challenges in Agricultural Production
• Declining number of farm laborers
• Depletion of primary farmland• Debates on genetically altered
food• Reducing number of farms and
increasing the size of farms
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Farm Number in Michigan
020000400006000080000
100000120000140000160000180000
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55
Year (1950 to 2004)
Farm
Num
ber
Michigan Farm Land in 1000 acres
0
5000
10000
15000
20000
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55
Year (1950-2004)
Source: USDA National Agricultural Statistic Service www.nass.usda.gov 10/5/2006 98