Phosphate sorption by calcareous vertisols and inceptisols of Spain
1989
Solis, P. | Torrent, J.
The study of phosphate sorption by soils has practical interest but little is known on the quantitative importance of phosphate sorption by Vertisols and the soil properties affecting it. In this study we examined phosphate sorption by 24 samples of calcareous Vertisols and associated Inceptisols of southern Spain. Sorption isotherms were described by the Freundlich equation. The amount of phosphate sorbed at 6 d at 1 mg P L-1 equilibrium concentration was highly correlated with the percentages of citrate-dithionite-bicarbonate extractable Fe (Fed) and clay; regression analysis suggested that the Fe oxides, as estimated by Fed, were the most active sorbents. In contrast calcium carbonate seemed to play a secondary role in sorption. Phosphorus buffer capacity was also highly correlated with the content in Fe oxides (r = 0.79) but less with clay content. Little sorption took place after 6 d for equilibrium concentrations of about 1 mg P L-1. Long-term sorption was affected by calcium carbonate content; Fe oxides seemed to contribute little to that process. Buffer capacity measured from P quantity and intensity changes produced by cropping was similar in magnitude and weakly correlated with the buffer capacity calculated from sorption isotherms in the laboratory. Thus, sorption curves can provide an estimate of the buffer capacity in desorption by plants for the soils studied.
显示更多 [+] 显示较少 [-]