Phosphate is a major nutrient required for plant growth. Find out how it reacts in the soil, what affects its availability, types of fertilizer and how to improve efficiency.
Phosphorus or phosphate
Phosphorus is a chemical element with the symbol P and atomic number 15. Phosphorus is not found as a free element in nature on earth because it is highly reactive and quickly bound to other elements. As part of the building blocks of nature – found in DNA, RNA, and ATP and as part of cell membranes – phosphorus is essential for all living cells.
In crop production, phosphorus is generally absorbed in the phosphate form, primarily the orthophosphate ion. Throughout this website, for simplicity we will refer to phosphorus in the phosphate form. In other publications, references to phosphorus may be in the elemental P form.
The phosphorus content of fertilizers is expressed as P2O5. This is the standard designation for relative P content. To convert P to P2O5, multiply P by 2.3.