Water quality: Evaluation of nitrate leaching potential in Minnesota glacial outwash soils using the CERES-Maize model

This study examined how the CERES-Maize model could be used to identify N and irrigation management practices that minimize nitrate leaching as well as provide economical corn (Zea mays L.) yield in glacial outwash soils of Minnesota. The model was validated against 2 yr of experimental data on corn grain yield, N uptake, and nitrate leaching for control and three N fertilizer application rates under two irrigation schedules on a sandy loam soil at Staples, MN. Simulated values were close to the measured corn yield, and were within the range of differences for similar comparisons. Simulations using 31 yr of climatic data showed that an irrigation trigger deficit as low as 30% had little impact on corn yield but significant impact on reduced percolation and nitrate 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 from soils in Wadena County, MN. As expected, he high risk soils had the lowest water holding capacity and the highest drainage coefficient. The factors affecting the risk of nitrate leaching are: irrigation schedule > climatic variability = N application rate. Linking a validated simulation model with a solid survey data base provides a valuable tool in site specific assessment and prescription of best irrigation and N management practices for the glacial outwash soils of the North Central region.