Incorporating Uncertainty Estimates into the KY P Index.

The phosphorous (P) index is an important tool for identifying and evaluating conservation practices aimed at reducing P losses from agricultural fields. There exists, however, an inherent amount of uncertainty in its prediction of P loss risk, though this is often ignored by P index developers and users. In this study, we conducted an uncertainty analysis with the Kentucky phosphorus index. We present and discuss the different sources of error associated with P indices and discuss potential approaches for estimating these uncertainties and including them in applications of the P index. Results from this study highlight the importance of including reasonable estimates of prediction uncertainties when using P indices to predict the risk of P loss from agricultural fields.