| Despite the long-term efforts in research and technology transfer to improve the efficiency of nutrient management, agriculture has been cited as a major nonpoint source of nutrients in ground and surface water pollution. Even with research and adoption, continued policy and other changes pose farmers with management challenges. One management area that has received considerable public attention is nutrient management. In many states nutrient management has become a crucial component of agricultural planning. Kentucky's reclaimed surface mined lands pose a new challenge to the existing literature of agricultural nutrient impacts on water, air, and soil quality.; One purpose of this work was to evaluate nutrient management strategies (irrigation, injection, and surface application methods) on surface mined reclaimed farm lands. The computer simulation model Opus was used to generate the biophysical data needed to derive the economic analysis. When applying liquid swine manure in a single-N application, the high costs of nutrient application combined with low crop productivity lead to large negative returns. This was true regardless of manure nutrient technology and crop choice. However, rather than speculate using the simulation data generated by Opus, efforts turned to the development of a dynamic mathematical model that leads to specific insights relative to maximizing economic profits while jointly minimizing nutrient releases to ground and surface water and accounting for the social costs (or nutrient tax) of the degradation of water quality. This model uses stylized expressions to illustrate a farmer's profit maximizing crop nutrient management decision subject to equations that describe the biophysical processes that determine the amount of nutrient released into surface and ground water.; As the social cost of leaching increases relative to the social cost of runoff, remediation costs increase, and changing water uses create more stringent water quality standards (i.e., boatable to drinkable water), then crop output would be decreasing. The cost of applying nutrient, through its effects, would be symmetrical to its effect that output price would have on changes in the amount of nutrient applied to the field. A decrease in the crop price would have the same negative impact on a production input (i.e., fertilizer, pesticides, etc) holding all other prices and variables constant. An increase in the price of an input would imply a reduction in output and/or change in crop rotation, but only to the extent that this decrease in production is not recovered by the decrease in social cost resulting from decreased leaching and/or runoff for a given location, ceteris paribus. |
