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ARS Home » Pacific West Area » Pullman, Washington » Northwest Sustainable Agroecosystems Research » Research » Publications at this Location » Publication #92755
Title: MEASURING AND MODELING SOIL EROSION AND EROSION DAMAGES

Author
item McCool, Donald
item BUSACCA, A - WASHINGTON STATE UNIV.

Submitted to: Soil and Water Conservation Society
Publication Type: Monograph
Publication Acceptance Date: 6/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soil erosion models play an important role in selecting crop management practices to protect our soil resource base from excessive soil erosion. The Northwestern Wheat and Range Region has a unique climate that requires that these models include components for winter erosion including snowmelt and frost restricted soils that are highly erodible as they thaw. The effects of erosion have also been quantified. These effects are generally greatest when soils are shallow to rock or where previous erosion has removed the topsoil and less productive material remains. At present, models that link soil erosion with the effects of erosion on productivity have not been validated for the Northwestern Wheat and Range Region.

Technical Abstract: Selecting crop management practices to protect our soil resource base from degradation requires predictive tools and erosion models. The Northwestern Wheat and Range Region offers unique challenges in erosion modeling and determining the effects of erosion on productivity. Unlike other areas of the USA, most water erosion occurs during the winter months from rainfall and snowmelt. Soils frequently freeze with a water restrictive frost layer. Frozen soils have a very low shear strength when they thaw and erode quite easily with small amounts of rainfall or runoff. Furthermore, the wind-deposited soils are of variable thickness over rock, water restrictive layers are present in the soils of much of the area, slopes range from gentle to quite steep, and there are major precipitation gradients. Significant progress has been made since the inception of STEEP in both erosion modeling and in determining the effects of erosion, primarily through decreases in topsoil depth, on productivity. During the STEEP project, regionalized relationships for factors of the USLE and RUSLE were developed and have proven reliable. Testing of WEPP is currently in progress. Concurrently, effects of erosion on productivity were determined. Effects of erosion are not evident when topsoil depth is great. However, for shallow soils and soils that have lost large amounts of topsoil such that water and root restrictive layers are present in the water extraction zone, soil erosion has a significant impact on productivity, mostly through effects on the available water supply. At present models that link soil erosion with the effects of erosion on productivity are not available or have not been validated for the region.