CORN YIELD - EROSION RELATIONSHIPS OF REPRESENTATIVE LOESS AND TILL SOILS IN THE NORTH CENTRAL UNITED-STATES

A study was started in 1984 to examine erosion-productivity relationsh ips on representative soils from the North Central United States. The project was designed to minimize the effects of landscape position and agronomic practices on data interpretation. Soil climate, and agronom ic data were collected according to standardized procedures on replica ted erosion classes located in similar landscapes. Relative yield loss for erosion class 3 averaged 17 percent on glacial-till derived soils and 8 percent on loess derived soils during the study period. Growing season precipitation and productivity index (PI) gave the best fittin g regression model for yield in the glacial-till derived soils (R2 = 0 .61). On loess derived soils, addition of other variables to the regre ssion equation did not greatly improve the R2 obtained from using grow ing season precipitation as the only predictor (R2 = 0.29).