Abstract
This study evaluates the effect of nitrogen fertilizer-use tax on nitrate-N runoff from the Des Moines Watershed in Iowa. This objective is achieved by developing the integrated modeling framework consisting of the land use and SWAT models. The land use model predicts farmers' crop choice, crop rotation, and conservation tillage adoption in the watershed. Predicted land use changes under the fertilizer-use tax are then integrated into the SWAT model to assess the level of nitrate-N runoff from the watershed. This study finds that the nitrogen fertilizer-use tax reduces “polluting” agricultural acreage and promotes “non-polluting” cropping practices. Although high tax rates are needed for significant land use changes, 250% tax rate is shown to reduce the aggregate nitrate-N runoff by 70% from the watershed.
