SOIL NITRATE LEACHING POTENTIAL INDEXES - USING A SIMULATION-MODEL AS A SCREENING SYSTEM

Simulation models LEACHM-N (Leaching Estimation and Chemistry Model) and NLEAP (Nitrate Leaching and Economic Analysis Package) were first tested using NO3 leaching data obtained from lysimeter and tile drainage studies conducted at three University of Minnesota experiment stations. Both simulation models did well in simulating total (seasonally accumulated) leaching loss of NO3-N from the soil profile. LEACHM-N was selected as a screening tool to develop soil NO3 leaching potential (NLP) ratings using soil survey information and representative county weather station data. Simulated growing season total NO3-N leached from the soil profile (below 1.5 m) were used as NLP index. Crop management practices and initial N were kept constant. Soil NO3 leaching potential ratings for three Minnesota counties, Redwood, Stearns, and Sherburne were developed using this method. This soil NLP rating information was included in the Soil Survey Information System (SSIS) to create leaching potential rating maps, which can be used to plan best N management schemes.