| This dissertation consists of three papers on agricultural nonpoint source pollution and control. The first paper focuses primarily on agricultural land use changes under alternative conservation policies. The second and third papers address environmental implications of these policies and their cost effectiveness.; In the first paper, the effect of alternative conservation policies on agricultural land use in the Upper Mississippi River Basin is quantitatively evaluated. Site-specific land use decisions are analyzed using a set of discrete choice models and site-specific economic and physical information. The models are then used to predict farmers' choice of crop, crop rotation, and participation in the Conservation Reserve Program under alternative conservation policies. Results suggest that acreage planted to "polluting" crops (corn and soybean) are quite responsive to the fertilizer-use tax, but not quite as responsive to the two payment programs considered in this paper.; In the second paper, the social costs of alternative conservation policies are estimated for reducing nitrate-N concentrations in the Upper Mississippi River. This objective is achieved by developing an integrated modeling framework consisting of economic and physical models. Results suggest that the nitrogen fertilizer-use tax is much more cost effective than the three payment programs. Incentive payments for conservation tillage are most cost effective among the three payment programs, but can only reduce nitrate-N concentrations to a limited level. The potential of incentive payments for corn-soybean rotation is even more limited. Although the Conservation Reserve Program can achieve the highest level of nitrate-N concentrations reduction, it imposes the highest cost to society.; In the third paper, the relative efficiency between the targeted and uniform fertilizer-use taxes for reducing agricultural water pollution is estimated. This paper adds some refinements to the integrated model developed in the second paper, for assessing nitrate-N runoff from the 9 subbasins in the Des Moines Watershed. In contrast to previous studies, results in this paper suggest that the targeted fertilizer-use tax outperforms the uniform tax under spatially heterogeneous conditions. The targeted fertilizer-use tax reduces the aggregate farm profit loss under the uniform tax by up to 30 percent in this watershed. |
