The role of policy in social-ecological interactions of nitrogen management in the Mississippi River basin.

Excess nitrogen (N) loading in the Mississippi River basin is a major water quality issue, encompassing large spatial scales and feedbacks between social and biophysical entities. Effective management depends on reductions in agricultural N loading, mainly from the Corn Belt region in the upper reaches of the basin. In this study, we evaluated the role of federal Nutrient Task Force policy on N management from 2000 to 2015. We analyzed trends in nitrate (NO3 - ) concentrations from monitoring data in 148 priority watersheds. We compared water quality trends with state nutrient reduction strategies, monitoring efforts, and land use. Of the 148 watersheds, 13 displayed a significant decrease in NO3 - concentrations, 24 displayed a significant increase, 51 displayed a nonsignificant trend, and 60 had insufficient data to analyze. We demonstrate that policy efforts on a large scale are slow to establish, but states and watersheds that showed signs of policy acting successfully could serve as examples for improved N management moving forward. Despite considerable variability, states with the most comprehensive strategies, evidenced by word count and presence of recommended elements, were almost exclusively located in the Corn Belt region. States with more thorough nutrient reduction strategies also tended to have a larger number of monitoring sites in priority watersheds (R = .42), demonstrating the potential for adaptive management. States with the most consistent improvements in NO3 - concentrations tended to have the most comprehensive policies, whereas variation in water quality trends was partly attributed to land use factors including slope and dominance of corn (Zea mays L.) and soy [Glycine max (L.) Merr.].

The Impact of Federal and State Conservation Programs on Farmer Nitrogen Management.

The U.S. federal government, as well as many state and local governments, operate a number of conservation programs aimed at ameliorating the environmental problems associated with agriculture. While motives and barriers to conservation program participation and adoption of conservation practices have been extensively studied, the direct impacts of programs on ongoing farm operations remains underexplored. To examine the effects of conservation programs on nitrogen management, an aspect of crop production with significant environmental impacts we conducted interviews with 154 corn producers in three Midwestern U.S. states with a range of program experiences. We found that programs shifted farmer N management behavior through three social processes: (1) engaging farmers in the conservation system by introducing them to the state and federal conservation agencies, (2) incentivizing trialing of specific N management practices, and (3) increasing practice adoption through continued program engagement. Working-lands programs were far more effective at shifting on-farm nutrient management practices than land retirement, certification, or outreach-based programs, though all programs had the indirect benefit of increasing farmer familiarity with conservation agencies and programs. Working-lands programs directly motivated practice adoption; including soil testing regimes, implementing nutrient management plans, and splitting nitrogen applications to improving availability; by reducing producer risk and providing technical assistance, especially whole-farm planning. The additional benefits of all programs were moderated by participant selection bias, in particular that program participants were more predisposed to conservation efforts by existing stewardship and innovation attitudes.