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ARS Home » Pacific West Area » Pullman, Washington » Northwest Sustainable Agroecosystems Research » Research » Publications at this Location » Publication #242513
Title: Soil and Water Challenges for Pacific Northwest Agriculture

Author
item SCHILLINGER, WILLIAM - Washington State University
item PAPENDICK, ROBERT - Washington State University
item McCool, Donald

Submitted to: Soil Science Society of America Journal
Publication Type: Book / Chapter
Publication Acceptance Date: 3/16/2010
Publication Date: 4/5/2010
Citation: Schillinger, W.F., Papendick, R.I., McCool, D.K. 2010. Soil and Water Challenges for Pacific Northwest Agriculture. Soil and Water Conservation Advances in the United States. SSSA Special Publication 60. pp 47-79. T.M. Zobeck and W.F. Schillinger, editors. © 2010. SSSA, 677 S. Segoe Rd., Madison, WI 53711, USA.

Interpretive Summary: Soil and water conservation has been a major concern in the Inland Pacific Northwest since shortly after the onset of farming in the early 1860s. Some of the largest historic water erosion rates in the USA have occurred on steep slopes of the region. Rapid snowmelt or rain on thawed soil overlying a frozen layer causes the greatest water erosion, especially on winter wheat fields following summer fallow or grain legumes that produce little residue. The primary concerns with water erosion are loss of topsoil from 4.5 million acre (1.8 million ha) of croplands and accompanying degradation of water quality in the high and intermediate precipitation and cropping zone. In the 3.7 million acre (1.5 million ha) of croplands comprising the dry winter wheat/summer fallow cropping zone, severe soil loss and degradation of air quality from wind erosion are the major concerns. Here drought, excessive tillage, low production of crop residue, poorly aggregated soils with low organic matter content, and occasional high winds leave soils vulnerable to wind erosion. These soils are dominated by particles that are readily suspended and transported for long distances. Our study indicates that significant advances in water and wind erosion control have occurred since the 1970s, mostly through improved management of the soil surface and crop residues. Today's powerful tractors and modern implements allow farmers to conduct field operations in a timely manner in one pass across the field with reduced labor and energy use. Effective and efficient use of herbicides has largely reduced the need for repeated tillage operations and, on some farms, even eliminated all tillage. Numerous research advances and increased technical know-how, combined with economic incentives by government farm programs and increased energy costs have driven an ongoing transition to conservation-till and no-till farming.

Technical Abstract: Soil and water conservation has been a major concern in the Inland Pacific Northwest since the onset of farming 125 years ago. Some of the highest historic water erosion rates in the USA have occurred on steep slopes in the Palouse region where soil loss averaged 45 Mg ha-1 yr-1 and could reach 450 Mg ha-1 yr-1. Rapid snowmelt or rain on thawed soil overlying a frozen layer causes the worst water erosion, especially on newly-planted winter wheat (Triticum aestivum L.) fields following summer fallow or grain legumes that produce little residue. Primary concerns with water erosion are heavy loss of topsoil from 1.8 million ha of croplands in the high and intermediate precipitation zone, and the accompanying degradation of water quality. Heavy soil loss and degradation of air quality from wind erosion are the major concerns in the 1.5 million ha of croplands comprising the dry (< 300 mm annual precipitation) winter wheat – summer fallow cropping zone. Here drought, excessive tillage, low production of crop residue, poorly aggregated soils with low organic matter content, and occasional high winds leave soil vulnerable to blowing. These soils are dominated by particles < 75 um in diameter that are readily suspended and transported for long distances. Significant advances in water and wind erosion control have occurred in the past 30 years. Most approaches involve management of the soil surface and crop residues. Today's powerful tractors and modern implements allow farmers to conduct field operations in a timely manner. Effective use of glyphosate and other herbicides has largely reduced the need for repeated tillage operations and, on some farms, eliminated the need for tillage. Numerous research advances and increased technical know-how, combined with economic incentives from government farm programs and increased energy costs have fueled an ongoing steady shift to conservation-till and no-till farming.