Individual- and county-level factors associated with farmers' use of 4R Plus nutrient management practices

The 4R Plus approach to agricultural nutrient management-ensuring that the "right source" of nutrients is used at the "right rate," "right time," in the "right place," and combined with appropriate in-field and edge-of-field practices-is posited to lead to win-win outcomes for farmers and the environment. While industry and conservation organizations are promoting the approach, farmers have not yet adopted 4R Plus practices at rates sufficient to meet the state's nutrient reduction goals. We employed multilevel modeling with survey data from 6,006 Iowa farmers to examine the complex relationships among individual-and county-level social, economic, and ecological factors associated with 4R Plus practice adoption. We found that adoption was associated with clusters of factors at both the individual and county levels. At the individual level, the variable crop area was positively associated with predicting use of all 4R Plus practices except Right Rate. Farmers' perceived lack of agronomic capacity to address nutrient losses was negatively associated with use of all 4R Plus practices but the Right Source. At the county level, farmers in counties with a higher percentage of rented land were less likely to have adopted Right Time, Right Source, and Edge-of-Field practices. Those farming in counties with a greater average slope were more likely to adopt Plus practices, such as cover crops and terraces. County-level crop insurance coverage rate was negatively associated with In-Field and Edge-of-Field Plus practices. Overall, this study provides quantitative support for qualitative studies that call for conservation programs to simultaneously address factors operating at multiple scales to improve outcomes. Programs that combine local, direct assistance to farmers with broader efforts to remove structural barriers may be more likely to be effective at facilitating conservation adoption than those operating at one scale alone. Specific to 4R Plus programming, efforts that simultaneously help farmers address farm-level capacity barriers and improve policies and programs (e.g., crop insurance) to ensure encouragement rather than hindrance of practice adoption would likely lead to better environmental outcomes.