Edge-of-field research to quantify the impacts of agricultural practices on water quality in Ohio

When settlers first reached central and northwestern Ohio, they encountered sprawling forested wetlands. Many viewed these swamps as a barrier to prosperity and began to drain them by straightening and dredging stream channels and by installing subsurface drainage to remove excess water (Blann et al. 2009). Draining of these landscapes was a celebrated accomplishment since centuries of decaying vegetation that accumulated in these swamps had created organic-rich soils that are some of the most productive in the world. Without drainage, it would not be feasible to sustain agricultural production to meet the demands of a growing global population (Tilman et al. 2011). Drainage reduces the risk of crop loss from excess water stress, provides more uniform crop production amidst climate variability, gives farmers more control over field operations, and reduces crop susceptibility to pests and disease (King et al. 2015). Drainage, however, also increases the hydrologic connectivity between streams and agricultural fields through subsurface pathways (King et al. 2014). As a result, agricultural pollutants, such as nitrogen (N) and phosphorus (P), flow through subsurface tile drains to receiving water bodies where these loadings have been linked to deleterious impacts on water quality (Smith et al. 2015).