Best Management Practices For Phosphorus Fertilization
Phosphorus (P) is an essential nutrient for all forms of terrestrial life and is one of the 18 chemical elements known to be required for plant growth. In Colorado, agricultural soils generally contain from 800 to 2,000 pounds of total P per acre in the tillage layer. However, most of it is in insoluble compounds unavailable to plants. The remainder cycles within plants, animals, soil, and the soil solution in biologically available forms and organic P compounds. A simplified P cycle is depicted in Figure 1, showing the principal P inputs and sinks. In production agriculture, fertilizer and manure are the major P additions to this cycle. Without these inputs, intensive commercial agriculture would not be viable on many soils. However, proper management of soils and P fertilizers is essential to protect water quality from degradation.