The potassium status of some coarse textured soils of the south western region of Western Australia

Abstract

The total, hydrochloric acid soluble, and exchangeable potassium contents of two soils typical of large areas of the south-west coastal region of Western Australia and of two soils in this region which had received varying levels of potassium fertilizer were determined. It was found that all four soils were low in exchangeable K, containing less than 60 lb exchangeable K per acre in their surface three inches. One of the soils had an exchangeable K content of 0.21 m-equiv. per cent after 2 cwt KCl per acre and another 0.08 m-equiv. per cent after 1 cwt KCl per acre had been applied and satisfactory pasture growth had been made. These values are lower than those reported elsewhere for satisfactory plant growth. One soil, extremely low in exchangeable K and which responded to potassium fertilizer, was found to contain the high total K content of 1 per cent. Mineralogical examination disclosed that almost the whole of this was present as feldspar.