A METAMODELING APPROACH TO EVALUATE AGRICULTURAL POLICY IMPACT ON SOIL DEGRADATION IN WESTERN CANADA

A novel approach for integrating economic and environmental models is described in the context of evaluating soil degradation impacts of agr icultural policy in western Canada. The key element of this approach i s the development of metamodels, which are statistical summary functio ns of simulation data obtained from carefully designed experiments wit h physical process models. The metamodels ave 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-consu ming physical process simulation models. The estimated wind and water erosion metamodels are very robust, with the majority possessing R-squ are values in the range of 0.80 to 0.97. The efficiency of the metamod els in facilitating the integration of a policy modeling system is des cribed 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 sce nario is evaluated. The model-predicted economic welfare and environme ntal quality interaction suggests a clear win-win situation for societ y under this alternative policy scenario.