Am I wasting phosphorus?

Phosphorus is one of the most common elements found in plants, usually ranking 8th after carbon, oxygen, hydrogen (which combined make up around 95% of plant dry matter), nitrogen, potassium, silicon and calcium. Unlike these other 7 elements, phosphorus is almost universally deficient in unfertilised soils in south-eastern parts of Australia. 

Read this excellent concise literature review by Glenn Bailey to learn more about how phosphorus behaves in the soil, including fixing reactions, buffer capacity, available phosphorus, soil reserves, plant requirements and leaching.