Development of an Approach and Tool to Optimize Farm-Scale Phosphorus Management and Achieve Watershed-Scale Loading Targets

Stone Environmental, Inc. (2018). Development of an Approach and Tool to Optimize Farm-Scale Phosphorus Management and Achieve Watershed-Scale Loading Targets (Technical Report No. 89). Grand Isle, VT: Lake Champlain Basin Program

A new web-based tool, the Farm-P Reduction Planner (Farm-PREP), was developed to enable farmers to more effectively and efficiently identify modifications to their field operations in order to meet a target reduction in phosphorus (P) leaving the farm and help to achieve water quality improvement goals at the watershed scale. Development of this tool was motivated by the need to quantify reductions in P loads leaving farms due to the adoption of best management practices (BMPs) and to determine how those reductions compare to targets established based on the Lake Champlain Basin P Total Maximum Daily Load (TMDL). The Farm-PREP tool is based on the US Department of Agriculture, Natural Resource Conservation Service’s Agricultural Policy/Environmental eXtender Model (APEX). The APEX model is a physically based agronomic and water quality model designed for simulations at the field to farm/small watershed scale. The unique aspects of this project include the implementation of APEX through a streamlined, web-based user interface and the incorporation of optimization functionality that automatically identifies field-specific management options that meet water quality targets. The project represents a Phase 1 pilot of the Farm-PREP tool, with initial demonstration in the St. Albans Bay watershed in St. Albans, Vermont.