Identifying Best Management Practices to Minimize P Loss in a Tile Drained Landscape.

Phosphorus losses from agriculture have been identified as a primary contributor to harmful algal blooms in Lake Erie. The objectives of this presentation will be to provide estimates of cropping systems management and other conservation practices that can be used to minimize P losses from this landscape. In the St. Joseph River watershed, a primary tributary to the Maumee River, USDA-ARS has been monitoring water quantity and quality from fields and agricultural drainage ditches. Cropping systems being tested at the field scale include corn/soybean rotation and alfalfa/corn/soybean/wheat/oats. These fields include long-term no-tillage (~20 yrs), rotational tillage (tillage only before corn), and conservation tillage (> 30% residue cover at planting). Conservation practices tested include grassed waterways, blind inlets, and conservation buffers. Additionally, the APEX model is being calibrated and validated to assess the potential impact of conservation practices on water quality in this landscape. This work will help guide future management decisions to minimize P loading to Lake Erie.