Cycling of phosphorus in grazing systems

Summary

Phosphorus (P) is commonly one of the most limiting nutrients to pasture production in New South Wales.

Before addressing soil phosphorus levels under pastures it is important to gain a better understanding of the phosphorus cycle operating in our soils supporting pasture which is grazed by livestock.

In the soil there are a number of different phosphorus pools constantly interacting. These pools include:

• plant-available inorganic P (water soluble P)
• organic P (P associated with living and dead organic matter)
• less available inorganic P (poorly soluble mineral P tightly bound to clay particles).

This Primefact describes the chemistry and pathways of each of these phosphorus pools and the principles of fertilising with phosphorus.