phosphate rock concern

Weekly Times

August 2, 2010

THE depletion of phosphate rock could threaten the availability of fertiliser and the long-term future of Australian agriculture.

The diminishing world reserves of phosphate rock for manufacturing phosphorus fertiliser will be discussed at the 19th World Congress of Soil Science being held in Brisbane this week.

Australia, with its phosphorus-deficient soils, is more vulnerable than many other countries to the world supply of mined phosphorus running out.

Dr Eric Craswell from the Fenner School on Environment and Society at the Australian National University says the reason mined phosphate rocks are so critical to food production is that there is no substitute for phosphorus.

Phosphorus cannot be synthesised or manufactured in a laboratory and without sufficient phosphorus we cannot grow crops, he says.

A recent estimate suggests that global production of phosphorus fertilisers will peak in 2033 and will be one third of that peak level by the end of the 21st century. Irrespective of when the peak occurs, exploitation of a non-renewable resource such as phosphate rock will peak and prices will increase as it becomes more scarce.

Dr Craswell says further research is needed to improve the efficiency of phosphorus fertiliser manufacture and application, improve phosphorus recycling, and boost the efficiency with which crops utilise phosphorus from the soil.

A team of soil scientists and agronomists from the Queensland Governments Department of Environment and Resource Management (DERM) and Department of Employment, Economic Development and Innovation (DEEDI) is developing more effective diagnostic soil tests for assessing the status of available phosphorus of soils and more efficient phosphorus fertiliser application methods.

Principal Soil Scientist of DERM Indooroopilly, Dr Philip Moody, is presenting a paper on the teams work looking at how to improve techniques to measure soil phosphorus levels and develop new application methods to apply phosphorus in the plant root zone to maximise crop uptake and to minimise any potential losses.

Principal Agronomist of DEEDI Kingaroy, Dr Mike Bell, highlights not only phosphorus deficiency as an emerging issue for broadacre grain cropping in northern Australia, but also potassium and sulphur deficiencies.

Potassium, like phosphorus, is an essential element for plant growth and cannot be substituted with other elements. It is also a non-renewable mined resource that could one day run out.

Dr Bells team has found that soil reserves of potassium and sulphur in grain cropping regions of Queensland and northern NSW are being depleted and the high costs associated with replacing these nutrients could potentially make cropping unviable in these regions.