Some effects of cultivation and waterlogging on the availability of phosphorus in pasture soils

Abstract

Compared with growth on undisturbed soil, uniform mixing of the surface 4 in. of pasture soils caused a decrease in the yield of subterranean clover grown in pot culture. This was shown to be due to lowered availability of the soil phosphorus and was probably brought about by sorption of the available phosphorus, which had accumulated at the soil surface, by the unsaturated subsurface soil.

Short periods of waterlogging (1–2 days) also brought about lowered availability of soil phosphorus. This occurred both with undisturbed soil cores and with mixed soils, but was much more severe when the soil was mixed. The effect appeared to be due to the conversion of phosphate to non-available forms during the short period of anaerobic conditions. The phosphate sorption capacity of the soil was increased by the waterlogging treatment but decreased to its original value when the soil was air-dried.