This study investigates the environmental impacts of several forms of policies that offer farmers subsides in return for the adoption of conservation tillage. The policies differ as to whether the tillage practice or one of several environmental benefits is targeted. We develop an Environmental Lorenz Curve which fully represents the performance of the targeting policies, and show that this curve can be directly used to help select the optimal targeting strategy for special classes of social welfare functions. The model is applied to the state of Iowa.