Providing Critical Support to Minnesota Farmers for Phosphorus Risk Assessment

This proposal addresses an urgent need to update and revise the Minnesota
Phosphorus Site Risk Index (MNPI) tool. The MNPI, last updated in 2006, must be updated to correspond with a recent policy change by the USDA Natural Resources Conservation Service regarding how erosion is predicted across landscapes. While making this change, we propose to evaluate the overall performance of the MNPI across Minnesota to ensure its reliability as a way to estimate phosphorus loss. Inaccurate phosphorus risk assessment can have serious economic, environmental, and biological consequences. If risk assessment is too high, farmers may risk under-application and stunted yields. If risk assessment is too low, farmers risk losing phosphorus during runoff events and harming downstream ecosystems. High levels of phosphorus in freshwater lakes drive the development of harmful algal blooms (HABs). In Minnesota, HABs have led to serious incidents including human illness and death of pets. Increased pressure to limit phosphorus loss could lead to increased regulations on manure and fertilizer application in Minnesota. The proposed project aims to improve both the quality and usability of the MNPI. This work will provide critical support to farmers in voluntarily reducing nutrient losses while ensuring that they maintain adequate soil fertility.