Abstract
Legacy nutrients stored in agricultural soils are a substantial component of riverine nutrient discharge contributing to the eutrophication of aquatic ecosystems. These nutrient loads can persist and delay water quality initiatives, for example, those of the Great Lakes Water Quality Agreement which seek to reduce phosphorus (P) loads entering the Western Lake Erie Basin. In this watershed, approximately 5% of fields have P concentrations 2.5-fold greater than the maximum agronomic recommendations for corn and soybeans. Fields with these elevated-P concentrations (>100 mg P kg−1 soil) act as a source of legacy-P and discharge greater P loads. Implementing best management practices to treat runoff from these fields is desirable but finding them has been a challenge as soil test data are proprietary information creating an asymmetric information barrier. To overcome this barrier, we formed a public-private partnership that included agricultural retailers who conduct soil testing for farmers. Agricultural retailers who partnered with this project provided their soil P data and contacted farmers to gauge their interest, maintaining privacy for farmers until they expressed interest. Only 3.8% of soil samples in the provided data had elevated-P concentrations. In many cases, these elevated-P soils were confined to zones within fields, and 13% of fields had at least one elevated-P zone. We pursued these elevated-P fields as research sites for the implementation and monitoring of management practices. The agricultural retailers contacted 77 farmers with surveys, and 25 responded with interest in meeting the research team to discuss the project. Following a preliminary evaluation with the spatial data of fields operated by interested farmers, visits were arranged so that 12 research sites could be located. As indicated through the surveys, discussions with farmers, and soil data, many of the fields had accumulated elevated-P due to historic land-use (livestock, manure, or biosolid application) creating legacy sources. We conclude that public-private partnerships featuring agricultural retailers are a promising tool that may help overcome asymmetric information barriers to finding and managing agricultural fields with legacy-P that that disproportionately contribute to nutrient runoff.
Highlights
Legacy nutrients stored in agricultural soils pose a serious threat to downstream waterbodies as they steadily leach into surface and subsurface runoff
Despite substantial efforts to improve water quality, the response is often slower than desired, with legacy sources implicated as one reason for the lag in meeting desired water quality improvements (Sharpley et al, 2013; Melland et al, 2018; Van Meter et al, 2018)
Our Public-private partnership (PPPs) was initiated by a research team from Ohio State University (OSU and Extension), the United States Department of Agriculture-Agricultural Research Service (USDA-ARS), and The Nature Conservancy (TNC)
Summary
Legacy nutrients stored in agricultural soils pose a serious threat to downstream waterbodies as they steadily leach into surface and subsurface runoff. Agricultural discharge of nutrients has contributed to the eutrophication of many aquatic ecosystems (Smith et al, 2006; Diaz and Rosenberg, 2008). Reducing agricultural nutrient loads requires collaboration between public and private entities to efficiently manage this diffuse pollution. Nutrient management plans such as the Chesapeake Bay Program (2014), the European Economic Community (EEC) (1991), and the Great Lakes Water Quality Agreement (GLWQA; International Joint Commission, 2012) have largely targeted agricultural sources. Further demonstrating the relevance and widespread nature of this problem, a study of 143 watersheds across the United States concluded that legacy sources contributed to riverine export of phosphorus (P) in 49 watersheds at an average rate of 86 kg P km−2, compared to 56 kg P km−2 in 94 watersheds where P was still being applied (Stackpoole et al, 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
