The dissolution of North Carolina phosphate rock in some south-western Australian soils

To investigate the prospects for phosphate rock (PR) application in south-western Australia (WA), 228 soil samples were collected from the main agricultural areas and their chemical and textural properties analyzed. All the samples were incubated with North Carolina PR and the amount of PR dissolved was measured using the DELTACa technique. The amounts of PR dissolved were generally low and only 29 of the soils dissolved more than 40% of the added PR. These are located in the wettest area of WA, to the west of the 800mm isohyet. Within this area a variety of soil types were able to dissolve PR including vertisols, spodosols, alfisols, and ultisols. Of these the humic podzols and peaty sands appeared to have the best potential for PR application. It is also from some of these soil types that much P from water-soluble fertilizers is leached so that the slow release characteristics of PR fertilizers may be beneficial.