The sorption of phosphate (P) by four strongly acid Fijian soils from 0.01 M CaCl2 decreased with increasing pH up to pH 5.5–6.0 and then increased again. The initial decrease in P sorption with increasing pH appears to result from an interaction between added P, negative charge, and the electrostatic potential in the plane of sorption. The results of a sorption study, involving KCl or CaCl2 of
... [Show full abstract] varying concentrations as the background electrolyte and using Nadroloulou soil incubated with KOH or Ca(OH)2, suggested that the increase in P sorption at pH values > 6.0 was caused by the formation of insoluble Ca-P compounds. For some soils this is consistent with the results of an isotopic-exchange study in which incubation with lime caused marked reductions in the amounts of exchangeable P at high pH.
