No abstract

The problem of targeting CRP purchases to buy environmental amenities under productivity and environmental heterogeneity is considered. Gini coefficients and Lorenz curves are used to measure the effectiveness of spending under alternative targeting criteria. The environmental benefits considered are water erosion, wind erosion, surface water quality, and wildlife habitat. The three alternative targeting criteria examined include purchasing land according to (i) the benefit-to-cost ratio, (ii) the level of benefits, and (iii) the level of cost. Results indicate that the degree of variability and correlation determine the extent to which suboptimal targeting achieves a significant portion of available environmental benefits. Copyright 1996, Oxford University Press.

Complex mathematical simulation models are generally used for quantitative measurement of the fate of agricultural chemicals in soil. But it is less efficient to use them directly for regional water quality assessments because of the large number of simulations required to cover the entire region and because the entire set of simulation runs must be repeated for each new policy. To make regional water quality impact assessment on a timely basis, a simplified technique called metamodeling is suggested. A metamodel summarizes the inputoutput relationships in a complex simulation model designed to mimic actual processes such as groundwater leaching. Metamodels are constructed and validated to predict groundwater and surface water concentrations of major corn and sorghum herbicides in the Corn Belt and Lake States regions of the United States. The usefulness of metamodeling in the evaluation of agricultural nonpoint pollution policies is illustrated using an integrated environmental economic modeling system. For the baseline scenario, we estimate that 1.2% of the regional soils will lead to groundwater detection of atrazine exceeding 0.12 Mg/L, which compares well with the findings of an Environmental Protection Agency monitoring survey. The results suggest no-till practices could significantly reduce surface water concentration and a water quality policy, such as an atrazine ban, could increase soil erosion despite the conservation compliance provisions. Complex mathematical simulation models are generally used for quantitative measurement of the fate of agricultural chemicals in soil. But it is less efficient to use them directly for regional water quality assessments because of the large number of simulations required to cover the entire region and because the entire set of simulation runs must be repeated for each new policy. To make regional water quality impact assessment on a timely basis, a simplified technique called metamodeling is suggested. A metamodel summarizes the input-output relationships in a complex simulation model designed to mimic actual processes such as groundwater leaching. Metamodels are constructed and validated to predict groundwater and surface water concentrations of major corn and sorghum herbicides in the Corn Belt and Lake States regions of the United States. The usefulness of metamodeling in the evaluation of agricultural nonpoint pollution policies is illustrated using an integrated environmental economic modeling system. For the baseline scenario, we estimate that 1.2% of the regional soils will lead to groundwater detection of atrazine exceeding 0.12 •g/L, which compares well with the findings of an Environmental Protection Agency monitoring survey. The results suggest no-till practices could significantly reduce surface water concentration and a water quality policy, such as an atrazine ban, could increase soil erosion despite the conservation compliance provisions.

No abstract

A novel approach for integrating economic and environmental models is described in the context of evaluating soil degradation impacts of agricultural policy in western Canada. The key element of this approach is the development of metamodels, which are statistical summary functions of simulation data obtained from carefully designed experiments with physical process models. The metamodels are in turn used to predict the soil degradation impacts of farmers'land management responses to policy options. The metamodels provide flexibility to perform repeated policy scenarios without having to rerun the time‐and resource‐consuming physical process simulation models. The estimated wind and water erosion metamodels are very robust, with the majority possessing R‐square values in the range of 0·80 to 0·97. The efficiency of the metamodels in facilitating the integration of a policy modeling system is described and applied to a scenario of increased crop residue management. Using regional aggregates of net farm income, total economic, surplus (consumer plus producer surplus) and total soil loss the economic and environmental tradeoff between the status quo and a no‐till policy scenario is evaluated. The model‐predicted economic welfare and environmental quality interaction suggests a clear win‐win situation for society under this alternative policy scenario.