Predicting spatial distributions of nitrate leaching in northeastern Colorado

Abstract

ABSTRACT: Identification of regional problem areas for NO3-N leached from agriculture is important to farmers, extension, and action agencies to develop efficient management control strategies. A Nitrate Leaching and Economic Analysis Package (NLEAP) model/Geographic Information System (GIS) combination was tested for regional irrigated agriculture in eastern Colorado. Results indicated that the NLEAP NO3-N -leached (NL) index, an index of the amount of NO3-N leached below the rooting zone, was useful for describing the distribution of groundwater NO3-N concentrations across a 736 km2 (248 mi2) area when used in combination with a GIS. Comparison of observed NO3-N distributions in the South Platte alluvial aquifer with simulated NL distributions gave regional Pearson correlation coefficients of 0.59 and showed that the model could simulate the major observed groundwater NO3-N patterns.