Residual values of Australian rock phosphates

For years superphosphate has been the cheapest, convenient and most effective way of supplying phosphorus to newly cleared soils in Western Australia\u27s South-West that are acutely deficient in phosphorus. However its effectiveness as a phosphorus source falls markedly after application. Regular applications are needed to maintaine profitable pastures and crops on these soils. After a big jump in supperphosphate prices in the mid 970s, researchers tested the use of Australian rock phosphates as potentially cheaper alternative phosphorus fertilisers to superphosphate. On the none-leaching sands, as this article shows, none of the rock phosphates was as effective for plant growth as superphosphate in the year of application or in subsequent years. Research is now concentrating on measuring the residual value of fertiliser phosphorus for pastures so that phosphorus fertiliser recommendations can be more finely tuned