Soil Wind Erodibility Index in Seven North Central States

MULTIPLE regression equations were developed to estimate the wind erodibility index percent dry aggregates > 0.84 mm in diameter in Iowa, Kansas, Michigan, Minnesota, North Dakota, Ohio, and South Dakota following fall tillage and again before spring tillage. Significant variables affecting the fall index were soil texture (sand, silt, clay), organic matter, exchangeable calcium, location, and kind of tillage management. Most of these variables plus cumulative precipitation (between fall and spring) and the fall index affected the spring index. The kind of crop did not influence either index. With noted exceptions, the derived soil erodibility factors (I), which appear in the wind erosion equation, were within about 25% of those assigned by the Soil Conservation Service to the soils studied. The fall regression equation may be useful for estimating aggregate size distribution following tillage, a parameter needed for the new wind erosion prediction system (WEPS), now under development by the Agricultural Research Service.