Assessing the concept of control points for dissolved reactive phosphorus losses in subsurface drainage.

Agricultural phosphorus (P) loss, which is highly variable in space and time, has been studied using the hot spot/hot moment concept, but increasing the rigor of these assessments through a relatively newer "ecosystem control point" framework may help better target management practices that provide a disproportionate water quality benefit. Sixteen relatively large (0.85 ha) subsurface drainage plots in Illinois were used as individual observational units to assess dissolved reactive P (DRP) concentrations and losses within a given field over four study years.

Split-nitrogen application with cover cropping reduces subsurface nitrate losses while maintaining corn yields.

Artificial subsurface drainage is essential to sustain crop production in many areas but may also impair water quality by exacerbating nitrate (NO )-nitrogen (N) delivery downstream. Cover crops and split-N application have been promoted as key conservation practices for reducing NO -N losses, but few studies have simultaneously assessed their effect on water quality and crop productivity. A field study was conducted to evaluate the effects of N application timing and cover crops on subsurface drainage NO -N losses and grain yield in continuous corn (Zea mays L.