Effect of lead on plant availability of phosphorus and potassium in a vegetable-soil system.

Two typical red soils were sequentially cultivated with celery (Apium graveolens L.) and Chinese cabbage (Brassica chinensis L.) in a greenhouse to determine the effect of lead (Pb) on plant availability of phosphorus (P) and potassium (K) in the soils. The concentrations of available P as estimated by the 0.05 mol L-1 HCl-0.025 mol L-1 (1/2 H2SO4) extraction and available K estimated by the NH4OAc extraction method in the crop-free soils were not affected by Pb treatment. Plant P concentrations in the above-ground part of celery and Chinese cabbage exposed to Pb were either lower or showed no significant difference to the control.