Field scale discharge and water quality response, to drainage water management

Subsurface (tile) drainage, while necessary for viable agricultural crop production in the humid, poorly drained regions of world, has been linked to offsite nutrient transport, culminating harmful algal blooms and hypoxia downstream waterbodies. Drainage water management (DWM), also known as controlled promoted a method reduce nitrogen (N) phosphorus (P) loss from field scale tile drainage; however, subsequent changes surface runoff associated quality have not explored. Four years subsurface discharge, N, P two sets paired sites northwest Ohio, USA were evaluated using before-after control-impact (BACI) design quantify impact DWM. Mean event was greater (significant at one site) under DWM drainage discharge less both but significant. There no significant difference nitrate-N (NO3--N) loss; reductions NO3--N measured sites. Similar dissolved reactive (DRP) site), differences noted mean DRP loss. Total (TP) losses significantly site with runoff, reduced TP only site. These findings suggest that loss, highlighting any benefit respect or could be negated part by increased losses. Furthermore, these emphasize need understand natural resource concern which practice is targeted call additional research on implementation includes across range soil textures, cropping management, climates.