And it is an important one. To make informed decisions about P application, producers need to know what plant-available levels exist in their soil. Soil tests are the only reliable way to determine the status of available nutrients in a field. Reliable soil test results and recommendations depend upon good soil sampling, calibrated soil analysis procedures, and research-based fertilizer recommendation guidelines. With accurate soil test results, producers can calculate their specific fertilization needs and make good decisions about the application of P to meet reasonable crop yield expectations.
Phosphorus losses Phosphorus is strongly adsorbed by soil particles and readily retained in soil.
Therefore, if P moves to surface waters, it does so primarily with eroded soil, but it also is dissolved in runoff water. Avoiding P movement to streams, rivers, and lakes is largely dependent upon maintaining agronomically optimum and not excessively high levels of plant-available P in the soil, and then keeping that soil in place. Using best management practices such as conservation tillage, erosion control practices, soil testing, accounting for P from manure, and buffer strips go a long way toward improving water quality. Only with a long-term approach can soil P be adequately managed for optimal crop production and minimal environmental risk. Most manure contains a significant amount of crop-available P. Usually, it can supply the entire P requirements of one or more years of cropping.