Quantifying phosphorus losses from the agricultural system

Phosphorus is transferred from agricultural lands to water bodies dissolved in surface runoff, attached to eroded sediment, and leached through the soil profile. It is also removed from the agricultural system as a component of the harvested crop. While communicating with landowners and producers during the nutrient management planning process, it is important to emphasize the relative quantity of phosphorus tosses via these mechanisms. This manuscript covers methods of assessing these losses. Field specific parameters such as runoff volume, erosion rate, soil test phosphorus, and crop phosphorus concentration need to be considered in relation to estimates of total P enrichment ratios, sediment delivery ratios, and soil sediment enrichment ratios. These estimates can be used to assess how best soil and water conservation practices and other techniques minimize off-site transport of phosphorus. These estimates of phosphorus field loss will contribute to a better understanding of nutrient application risks, wise land use decisions, and increased implementation of management practices.