Modeling Dissolved Phosphorus Transport From Agricultural Watersheds In Central New York

Abstract

An important cause of freshwater contamination in the United States, soluble reactive phosphorus (SRP) loss from agriculture often occurs when overland runoff transports phosphorus (P) from manures and fertilizers to receiving waters. Because of the importance of overland runoff in transporting P, models that allow us to pinpoint the location and timing of overland runoff are an important tool for reducing SRP transport in overland runoff. We created a simple regional model that allows us to predict the timing and location of runoff in the northeastern United States. In addition, we conducted soil box experiments which indicate that SRP concentrations decline rapidly over time after manure fertilization, and this decline in P availability is affected by temperature. We developed an SRP model which predicts the SRP concentration after manure application, which, combined with the spatially explicit watershed model, allows for prediction of SRP loss from agriculture under a variety of manure timing scenarios. We find that in a 326 km2 watershed where farmers apply P to match crop needs, simply changing the timing of manure application to avoid periods of runoff have the potential to reduce manure-derived SRP in runoff by up to 40%. iii