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

Simulation models LEACHM-N (Leaching Estimation and Chemistry Model) a nd NLEAP (Nitrate Leaching and Economic Analysis Package) were first t ested using NO3 leaching data obtained from lysimeter and tile drainag e studies conducted at three University of Minnesota experiment statio ns. Both simulation models did well in simulating total (seasonally ac cumulated) leaching loss of NO3-N from the soil profile. LEACHM-N was selected as a screening tool to develop soil NO3 leaching potential (N LP) ratings using soil survey information and representative county we ather 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 potenti al ratings for three Minnesota counties, Redwood, Stearns, and Sherbur ne were developed using this method. This soil NLP rating information was included in the Soil Survey Information System (SSIS) to create le aching potential rating maps, which can be used to plan best N managem ent schemes.