Water Quality And Agriculture - USDA

Water Qualityand AgricultureStatus, Conditions, and TrendsWorkingPaper #16

Water Quality andAgriculture:Water Quality and Agriculture:Status, Conditions, and TrendsStatus, Conditions, and TrendsAcknowledgments . vList of Figures . viiList of Tables . xiContents:Executive Summary . 1Introduction . 7References . 10Chapter 1Soil Quality and Water Quality . 11Importance of soil quality . 11Soil quality indicators . 12References . 13Chapter 2Agrichemical Links to Water Quality . 15Sediment . 15Environmental damages . 16Irrigation systems, canals, and ditches . 16Floodplain sedimentation . 17Soil productivity . 17Water treatment . 17Practices to reduce sediment yield . 18Nitrogen . 18The nitrogen cycle . 18Environmental impacts . 19Nitrogen in ground water . 19Runoff and surface water . 20Management to improve nitrogen use efficiency . 22Conservation tillage . 22Rotations, cover crops, and nitrogen-scavenging crops . 23Filter strips . 23Source areas and in-field targeting . 23Phosphorus . 24The phosphorus cycle . 25Soil phosphorus . 26Sources and transport . 27Environmental impacts . 28(Working Paper # 16, July 1997)i

ContentsWater Quality and Agriculture:Status, Conditions, and TrendsManagement to reduce negative impacts of phosphorus use . 29Phosphorus sources and in-field targeting . 29Remedial strategies . 29Pesticides . 32Pesticide persistence . 32Setting Health Hazards for Pesticides . 33Soil properties that affect pesticides . 33Pesticide losses in field runoff and leachate . 34Management to reduce pesticide pollution . 35Salinity . 37Regional problems . 37San Joaquin Valley, California . 37Imperial Valley, California . 38Colorado River Basin . 38Arkansas River Basin . 38Saline seeps and salt water intrusion . 38Changes in agricultural resource management . 39Land use . 39Irrigated land . 40Soil erosion . 41Conservation Reserve Program . 41Nitrogen and phosphorus . 44Commercial fertilizers . 44Animal manures . 50Potential nitrogen and phosphate loss from farm fields . 52Pesticides . 54Pesticide use . 54Potential for pesticide loss from farm fields . 54References . 58Chapter 3Complexity of Measuring Water Quality . 63Monitoring objectives . 63Agricultural water quality monitoring . 64Monitoring approaches . 64Primary contaminants . 65Potential variables . 65Important ancillary variables . 67Design of monitoring programs . 67USGS National Water Quality Assessment . 68References . 68ii(Working Paper #16, July 1997)

ContentsChapter 4Water Quality and Agriculture:Status, Conditions, and TrendsA States-Based Snapshot — Surface Water . 69Water quality — the 1994 305(b) Report . 69Impairment sources . 70Impairment causes: rivers and streams . 72Impairment causes: lakes, reservoirs, and ponds . 75Impairment causes: estuaries . 77Chapter 5Measured Water Quality Status and Trends . 81Surface water quality . 81Rivers and streams . 81Dissolved oxygen . 81Fecal coliform bacteria . 81Dissolved solids . 85Nitrate . 85Total phosphorus . 86Suspended sediment . 86Transport in streams and rivers . 86Land use effects on nutrients and sediment transport . 90Missouri Sedimentation from 1993 Flood . 91Herbicides transport . 92Lakes and reservoirs . 93Contaminant transport to selected reservoirs . 93Reservoir sedimentation rates . 94Pesticides in rainfall and surface water . 96River and stream water quality — conclusions . 96Lake Erie . 97Major estuaries . 98Wetlands . 100Chesapeake Bay . 103Ground water quality . 104Monitoring issues . 105Pesticides in ground water . 106Nitrate in ground water . 107References . 111Chapter 6Water Quality through Agricultural Policies and Programs . 115Current USDA programs . 115USDA’s water quality initiative . 115The 1985 and 1990 Farm Bills . 116The 1996 Farm Bill . 117Long-standing USDA programs . 117(Working Paper # 16, July 1997)iii

Water Quality and Agriculture:Status, Conditions, and TrendsOther USDA activities . 118Non-USDA Federal programs . 119State regulations affecting agriculture . 120Input controls . 120Land use controls . 121Economic incentives . 121State management overview . 122References . 122Acronymsiv. .125(Working Paper #16, July 1997)

AcknowledgmentsWater Quality and Agriculture:Status, Conditions, and TrendsThis report, the result of extensive collaboration within the U.S. Department of Agriculture and with other departments, was prepared byJohn D. Sutton, USDA/NRCS. Key contributors include Joseph Bagdon,USDA/NRCS; Jerry Bernard, USDA/NRCS; Steve Brady, USDA/NRCS;Barry Burgan, U.S. EPA; Neil Carriker, TVA; George Cross, USDA/NRCS;Daniel Farrow, NOAA; Ronald Follett, USDA/ARS; Dennis Helsel, USGS;Anne Henderson, USDA/NRCS; Charles Job, U.S. EPA;Robert Kellogg, USDA/NRCS; Charles Lander, USDA/NRCS; KennethLanfear, USGS; James Lewis, USDA/NRCS; James Maetzold, USDA/NRCS;Mark Ribaudo, USDA/ERS; Andrew Sharpley, USDA/ARS;E. Tim Smith, USGS; and Donald Woodward, USDA/NRCS. Clive Walker,USDA/NRCS provided an especially thorough and thoughtful review.Resource analysis and assessments are ongoing functions of the NaturalResources Conservation Service. These assessments play an important rolein how we keep the public and policymakers informed about emergingconservation and environmental issues, develop plans to conserve ournatural resources, and design programs to provide national leadership forthe conservation of natural resources on America’s private lands. Foradditional information about this or other NRCS resource assessmentpublications, contact the Director of the Resource Assessment and Strategic Planning Division, USDA, Natural Resources Conservation Service, P.O.Box 2890, Washington, DC 20013.July 1997(Working Paper # 16, July 1997)v

Water Quality and Agriculture:Status, Conditions, and Trendsvi(Working Paper #16, July 1997)

List of FiguresWater Quality and Agriculture:Status, Conditions, and TrendsFigure 1-1Changes in soil quality affect water quality . 13Figure 2-1The nitrogen cycle . 18Figure 2-2Land use and mean organic and total nitrogenconcentrations in stream data . 21Figure 2-3The phosphorus cycle . 25Figure 2 4Percentage of soil samples testing high orabove for phosphorus in 1989 . 26Figure 2-5Phosphorus loss in runoff as a function of landuse in the United States . 28Figure 2-6Average annual soil erosion by water on croplandand Conservation Reserve Program land, 1992 . 42Figure 2-7Average annual soil erosion by wind on croplandand Conservation Reserve Program land, 1992 . 42Figure 2-8Total wind erosion and sheet and rill erosionon cropland, 1982 to 1992 . 43Figure 2-9Acreage enrolled in the Conservation ReserveProgram, as of the 12th signup (1993), by FarmProduction Region . 43Figure 2-10Change in average annual soil erosion by wind andwater on cropland and Conservation ReserveProgram land, 1982 to 1992 . 44Figure 2-11Nitrogen consumption, all applications,1982 to 1992 . 45Figure 2-12Phosphate consumption, all applications,1982 to 1992 . 46Figure 2-13Nitrogen used on corn, rate per fertilized acrereceiving nitrogen, selected States, 1982 to 1992 . 47Figure 2-14Phosphate used on corn, rate per fertilizedacre receiving phosphorus,selected States, 1982 to 1992 . 48Figure 2-15Nitrogen used on wheat, rate per fertilized acrereceiving nitrogen, selected States,1982 to 1992 . 48Figure 2-16Phosphate used on wheat, rate per fertilizedacre receiving phosphorus, selected States,1982 to 1992 . 48Figure 2-17Nitrogen used on soybeans, rate per fertilizedacre receiving nitrogen, selected States,1982 to 1992 . 49(Working Paper # 16, July 1997)vii

List of FiguresviiiWater Quality and Agriculture:Status, Conditions, and TrendsFigure 2-18Phosphate used on soybeans, rate per fertilizedacre receiving phosphorus, selected States,1982 to 1992 . 49Figure 2-19Nitrogen used on cotton, rate per fertilized acrereceiving nitrogen, selected States, 1982 to 1992 . 50Figure 2-20Potential nitrogen and phosphate fertilizer lossfrom farm fields . 53Figure 2-21Pesticide use on selected crops, by pesticide type,1964 to 1992 . 54Figure 2-22Pesticide runoff and leaching potential for fieldcrop production . 55Figure 4-1Percent of rivers and streams; lakes, reservoirs,and ponds; and estuarine waters assessed,by NRCS Region, 1992 and 1993 . 70Figure 4-2Assessed river miles reported impaired from allsources, by cause of impairment and NRCS Region,1992 and 1993 . 72Figure 4-3Assessed river miles impaired from all sourcesas a percentage of miles reported, by cause ofimpairment and NRCS Region, 1992 and 1993 . 73Figure 4-4Assessed lakes, reservoirs, and ponds reportedimpaired from all sources, by cause of impairmentand NRCS Region, 1992 and 1993 . 75Figure 4-5Assessed lakes, reservoirs, and ponds reportedimpaired from all sources, as a percentage ofassessed area, by cause of imp

Water Quality and Agriculture: Acknowledgments Status, Conditions, and Trends This report, the result of extensive collaboration within the U.S. Depart-ment of Agriculture and with other departments, was prepared by John D. Sutton, USDA/NRCS. Key contributors include Joseph Bagdon, USDA/NRCS; Jerry Bernard, USD