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Beyond the Bale : June 2011
FAST FACTS l Peak P -- when demand for phosphorus (P) outstrips supply -- is now not expected to occur in the near future. l Pursuing ways to improve the effectiveness of fertiliser P use will, nevertheless, provide opportunities to improve the profitability, sustainability and the environmental credentials of Australian agriculture. l A new tool provides information on adequate P levels, return on investment and stocking rates -- to help producers in their P application decision making. Phosphorus (P) plays an essential role in grazing businesses and accounts for about 10 per cent of all expenses. It is the largest single overhead cost after labour costs. So it is not surprising that the availability of affordable P supplies and their efficient use are of great interest to woolgrowers. In 2009, there were fears that within 25-30 years, global P supply might no longer keep up with demand resulting in a sharp increase in the cost of P fertilisers. However, following a reassessment of the size of world P resources, high quality P reserves are now thought to be four times larger than previous estimates and the risk of Peak P in the foreseeable future is relatively low. While there will always be some uncertainty about the size of global P reserves, debate about the sustainability of P is inevitable due to the crucial role fertilisers play in food security. Pasture agronomist with CSIRO's Sustainable Agriculture Flagship, Dr Richard Simpson points out that while it is good news P shortages are probably not imminent, it is not an excuse for delaying action to find ways to use P more effectively in agriculture. "We have seen the price of P fertiliser double over the past decade and as the world moves to mine new P reserves, which are of lower quality or harder to extract, the cost of P fertiliser will continue to increase," Dr Simpson says. "It is important to remember that P is a finite resource and we need to use it efficiently." Presently, Australia sources about half of its annual P requirements domestically and the remainder from overseas. At a national level we apply about four units of P as fertiliser to produce products that contain only one unit of P. The difference (about three quarters of the P used in agriculture) accumulates in the soil. This is an inefficiency that Dr Simpson says is being addressed by research. Dr Simpson says P use efficiencies vary between Australian farm enterprises, with grazing being typically 20-40 per cent efficient (about 5 units of P are applied as fertiliser to achieve one unit in farm products), and cropping being typically up to 60 per cent efficient. "If improvements to P use efficiency were easy, we would have already done it; we need to start looking outside the box to find more gains." However, inefficiency associated with P use, especially in grazing enterprises, also represents a potential opportunity to reduce costs. "We are investigating how plant roots can explore soil for nutrients more effectively and capture less-accessible P, which is already in the soil. "There may also be gains to be made by rethinking how fertilisers deliver P to plants. Efficiencies such as this have been used in the grains industry for many years because it has been possible to band P fertilisers close to seeds at sowing." Dr Simpson says while R&D will take several years to trial these concepts in the field, there are some immediate gains to be made on farms. "There is evidence to suggest that some farm businesses are not following 'best practice' fertiliser recommendations and are operating at soil fertility levels in excess of the level necessary for maximum production. "On these farms, immediate fertiliser input savings of up to 30 per cent may be possible by using soil testing more effectively and managing soil P fertility in a targeted way." When making P application decisions for their property, woolgrowers can use the new 'Five Easy Steps' tool (see article opposite). This tool provides information on adequate P levels, return on investment and stocking rates. More information: View the slides that Dr Simpson presented at the AWI/MLA R&D Insights forum in March on the AWI website at www.wool.com/RnDInsights On some farms, immediate fertiliser input savings of up to 30 per cent may be possible by using soil testing more effectively and managing soil P fertility in a targeted way. PHOTO: CSIRO, PLANT INDUSTRY June 2011 BEYOND THE BALE 28 ON-FARM Using phosphorus efficiently to red "IT IS IMPORTANT TO REMEMBER THAT P IS A FINITE RESOURCE AND WE NEED TO USE IT EFFICIENTLY" DR SIMPSON