Nitrogen and phosphorus management on Wisconsin farms: Lessons learned for agricultural water quality programs

ABSTRACT:

Farming systems that combine animals, forage, and cash grain production have the opportunity to augment commercial fertilizers with nutrients generated on a farm. To do this, the farmer must weigh the economic benefits associated with a low-risk option of relying on commercial nutrients against technological and managerial uncertainties associated with using on-farm nutrient sources. This decision by the farmer must be made in the context of maintaining a financially-viable farm while reducing the probability of environmental degradation caused by over-application of crop nutrients. Supposedly, best management practices (BMPs) promoted by water quality programs help the farmer achieve this objective.

A survey was conducted among Wisconsin livestock farmers to assess the application of all sources of nitrogen (N), and phosphorus (P₂O₅) in the production of corn. Nitrogen and phosphorus inputs were selected because they have been shown to negatively effect the surface and ground water resources when used in excess or in sensitive ecobgical areas. This research differed from more common attitudinal surveys of farmers by focusing on the actual agronomic behaviors associated with the management of crop nutrients in mixed farming systems.

Data from 1,928 farms in Wisconsin was used in this analysis to determine the overall nutrient application rates and use of BMPs. Results indicate that two out of three farmers apply excess nitrogen (N), which four out of five apply excess phosphorus (P₂O₅) for corn production. Few use the recommended BMPs in an appropriate fashion. These results indicate that farmers' actual behavior patterns must be brought into the design of both best management practices and implementation strategies for water quality programs.