ANALYSIS OF NITROGEN MANAGEMENT STRATEGIES USING EPIC

• Published in: Journal of the American Water Resources Association Vol. 34; no. 5; pp. 1199 - 1211
• Main Authors: Ramanarayanan, Tharacad S., Storm, Daniel E., Smolen, Michael D.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.1998
• Subjects: Agricultural management; best management practices; computer simulation; Criteria; Crops; Erosion; Fertilizing; Freshwater; Irrigation; Leaching; Management; Mathematical models; nitrate-nitrogen; Nitrogen; nitrogen management; nonpoint source pollution; Optimization; Productivity; Resources; Rotation; Water quality; USA, Oklahoma, Tipton
• ISSN: 1093-474X; 1752-1688
• DOI: 10.1111/j.1752-1688.1998.tb04165.x

This paper illustrates a method of using a hydrologic/water quality model to analyze alternative management practices and recommend best management practices (BMPs) to reduce nitrate-nitrogen (NO sub(3[sup]-)-N) leaching losses. The study area for this research is Tipton, an agriculturally intensive area in southwest Oklahoma. We used Erosion Productivity Impact Calculator (EPIC), a field-scale hydrologic/water quality model, to analyze alternative agricultural management practices. The model was first validated using observed data from a cotton demonstration experiment conducted in the Tipton area. Following that, EPIC was used to simulate fertilizer response curves for cotton and wheat crops under irrigated and dryland conditions. From the fertilizer response functions (N-uptake and N-leaching), we established an optimum fertilizer application rate for each crop. Individual crop performances were then simulated at optimum fertilizer application rates and crop rotations for the Tipton area, which were selected based on three criteria: (a) minimum amount of NO sub(3[sup]-)-N leached, (b) minimum concentration of NO sub(3[sup]-)-N leached, and (c) maximum utilization of NO sub(3[sup]-)-N. Further we illustrate that by considering residual N from alfalfa as a credit to the following crop and crediting NO sub(3[sup]-)-N present in the irrigation water, it is possible to reduce further NO sub(3[sup]-)-N loss without affecting crop yield.