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.
Footnotes
B.K. Wylie, M.J. Shaffer, and M.K. Brodabl are soil scientists, Great Plains Systems Research Unit, U.S. Department of Agriculture, Agricultural Research Service, P.O. Box E, Fort Collins, Colorado 80522 tel (303) 490 8300; D. Dubois is the manager of the North Front Range Water Quality Planning Association, 500 E. Third, Loveland, Colorado 80537 tel (303) 962–2491; D. G. Wagner is a PhD student, Agricultural Engineering, Colorado State University, Fort Collins, Colorado 80523 (303) 492–5252.
- Copyright 1994 by the Soil and Water Conservation Society