Importance of phosphorus

Phosphorus is bound tightly to mineral components in the soils and is also contained in soil organic matter. This means that only a fraction of phosphorus in soil is actually available for plant uptake.

Phosphorus is removed from the farm system in crops or animal products. This needs to be replaced by application of additional phosphate fertiliser. Just like a bank account, the pool of nutrients in the farm system will support regular withdrawal for a while, but eventually the reserves become so low that the pool of nutrients (in this case phosphorus) needs to be topped up.