Metamodeling Potential Nitrate Water Pollution in the Central United States

Abstract

AbstractThis article presents a modeling system for identifying the spatial patterns of potential water pollution from N fertilizer use in the central USA. The model uses a geographic information system (GIS) and a statistical technique to integrate an environmental process simulation model with spatially referenced databases on crop management and resource characteristics. The potential for NO3‐N runoff and leaching was estimated for a total of 128 591 sites using information on soil, climate, crop, rotation, tillage, irrigation, and conservation practices at each site. For the entire study region, the average annual NO3‐N runoff and leaching, respectively, were estimated to be 5 and 3 kg ha−1, which accounted for about 7 and 4% of total N applied. The potential for NO3‐N runoff was relatively high in much of the Corn Belt, Kansas, and the Nebraska Platte River Basin, and the potential for NO3‐N leaching was relatively high in Ohio, Indiana, and southern Illinois and Missouri. Because much of the area with high leaching potential was tile drained, a large portion of the leached NO3‐N will be discharged to surface water, rather than continue downward to ground water. Finally, the model was applied to estimate the effects of a 25% reduction in N application rates and adoption of crop rotations on potential NO3‐N runoff and leaching.