Policy Implications of Ranking Distributions of Nitrate Runoff and Leaching from Corn Production by Region and Soil Productivity

Abstract

The purpose of this study was to understand the implications of farm-to-farm and regional variations in N runoff and leaching for targeting specific policies to reduce nutrient contamination. To do this, we estimated distributions of nitrate runoff and leaching for individual soils on nearly 150 farms in three farm production regions of New York and ranked the distributions according to second degree stochastic dominance criteria (SSD). Based on these rankings, it was evident that cropland across farms and regions of New York is so heterogeneous that it is impossible to target policies to reduce nitrate contamination based on farm or regional characteristics. A much clearer ranking was found when soils were grouped by productivity group as measured by corn (Zea mays L.) yield. Based on the estimated elasticities of nitrate runoff and leaching with respect to N application, one can target those areas where contamination problems are most severe by focusing on soils with potential yields greater than 125 bu/acre. For it to make sense to target lower productivity soils, the productivity of additional N application at the margin on the highest yielding soils would have to be about double that of the lower yielding group. Evidence indicates that the ratios of productivities are less than unity in all three production regions.