Phosphite (PO₃³⁻) is a reduced form of phosphate (PO₄³⁻), the familiar phosphorus source in traditional fertilisers. Although the two compounds are chemically related, their behaviours in plants and soils differ significantly. Phosphite is highly soluble and readily absorbed through both roots and foliage, making it a highly efficient delivery mechanism for phosphorus-related benefits, including disease and pest resistance, acting as a trigger for some of the plant's remarkable natural defence mechanisms.
