Why do we need phosphorus?
This year marks 350 years since the discovery of phosphorus - an essential element for life on earth. Phosphorus is a component of nucleic acids (DNA and RNA), essential for cell membranes, and for energy transactions in all living cells. It's also an important structural component of teeth and bones.
Although phosphorus is a relatively abundant element, many soils have low phosphorus levels for plant growth. More than 30 per cent of the world's crop lands are phosphorus deficient, including the majority of Australian soils.
Good agronomy and scientifically informed soil fertility management have guided Australia's phosphorus fertiliser use.Wheat yields have increased three-fold since the 1880s due largely to use of phosphorus fertiliser, along with legumes, better plants and improving farm technology. Pastures have also been transformed by the combined use of phosphorus fertiliser and pasture legumes such as subterranean clover.
However, 10 years ago an assessment of the known global phosphate rock "reserves" (from which fertilisers are made) suggested their longevity may be very limited to several decades. This sent shockwaves around the world.
While some regions of the world have fertile soils, or are oversupplied with phosphorus (eg Western Europe), other regions like ours depend on phosphorus fertilisers to maintain high food production from deficient soils.
New audits of global reserves quickly followed and dispelled the immediacy of the apparent crisis, estimating the world has 200-300 years of supply from phosphate rock reserves, at current rates of use.
These assessments have heightened global awareness of the importance of phosphorus for food security; the need to increase phosphorus-use efficiency along the whole supply chain (mining to food production), and the importance of recycling phosphorus from waste streams.
Phosphorus use may increase in time, but technology is also changing. The world has vast lower-grade phosphorus "resources" and it's likely that increases in the price of phosphorus, and improved mining and processing technology, will open the use of these resources.
The good news is that Australian farmers are already getting ahead of the game. Soil tests to guide efficient fertiliser use are well established; critical phosphate requirements of many crops and pastures have been determined, and farmers know where, when and how to place phosphorus fertiliser to maximum effect.
Researchers are investigating crop and pasture varieties that use phosphate more efficiently and improved fertiliser technology and practices. Many innovations are already in use on Australian farms, working to safeguard our precious phosphorus reserves.
Response by: Richard Simpson, CSIRO Agriculture and Food
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