Phosphate Facts

Imagine buying a new tractor and discovering six weeks later that it had lost 73% of its value. Contemplate your sense of loss, if weather extremes decimated 3/4 of your cash crop. There is a major investment made by many of us each year, where we actually receive just 27% of what we paid for. You would assume an outcry, farmers screaming, “scam!”, and demanding compensation.The industry that delivers this pitiful investment openly acknowledges these issues, but most of us remain unaware of our losses, or just adopt apathy and passively accept the inevitable.

DAP and MAP rank as Australia’s leading fertiliser investments. Most broadacre and horticultural enterprises will dutifully apply these granules each season, despite their amazing inefficiency. Within 6 weeks of application, over 75% of this soluble phosphate is lost. In fact, the CSIRO estimate that ten billion dollars of applied phosphate now lies locked up in farming soils. How does most of what you apply become part of this massive, frozen reserve. Here’s how it works:

All minerals can create bonds with other minerals due to their respective positive and negative charges, i.e., the positively charged cations are attracted to the negatively charged anions, like a nail to a magnet. The strength of the bond is related to the number of positive or negative charges involved. The mineral with the most negative charges is phosphorus. It has three charges, and this means it is strongly attracted to cations with two or more charges. Unfortunately, when it bonds to these cations, it becomes insoluble and no longer available to the plant.