In the spring of 2012, USDA released a new model that could prove very useful in targeting efforts, the Annual Phosphorus Loss Estimator, or APLE. This new tool can be used to estimate phosphorus losses on a field-scale. When applied across a whole farm, the tool can help develop targeted strategies to reduce these phosphorus levels.
Wisconsin’s P-Index tool is a closely related calculation tool to APLE that also estimates field scale erosion and runoff. More information and the tool itself can be accessed HERE.