EVALUATION OF NITRATE LEACHING POTENTIAL IN MINNESOTA GLACIAL OUTWASHSOILS USING THE CERES-MAIZE MODEL

This study examined how the CERES-maize model could be used to identif y N and irrigation management practices that minimize nitrate leaching as well as provide economical corn (Zen mays L.) yield in glacial out wash soils of Minnesota. The model was validated against 2 yr of exper imental data on corn grain yield, N uptake, and nitrate leaching for c ontrol and three N fertilizer application rates under two irrigation s chedules on a sandy loam soil at Staples, MN, Simulated values were cl ose to the measured corn yield, and were within the range of differenc es for similar comparisons, Simulations using 31 yr of climatic data s howed that an irrigation trigger deficit as low as 30% had little impa ct on corn yield but significant impact on reduced percolation and nit rate leaching, A procedure was developed to characterize the potential of nitrate leaching in outwash soils using the output from the CERES- Maize model. We used this procedure to characterize nitrate leaching f rom soils in Wadena County, MN, As expected, the high risk soils had t he lowest water holding capacity and the highest drainage coefficient. The factors affecting the risk of nitrate leaching are: irrigation sc hedule > climatic variability = N application rate, Linking a validate d simulation model with a soil survey data base provides a valuable to ol in site specific assessment and prescription of best irrigation and N management practices for the glacial outwash soils of the North Cen tral region.