Sulphate retention by New Zealand soils in relation to the competitive effect of phosphate

摘要

Abstract Retention of sulphate and phosphate ions added in solution, alone and in combination, was determined in percolation experiments using individual horizons from soils differing widely in parent material, degree of weathering, and level of native adsorbed sulphate. Weakly weathered soils, formed from moderately siliceous sedimentary parent materials and containing mainly 2:1 type (micaceous) clays contained little native adsorbed sulphate, and had little capacity to retain added sulphate. Moderately to strongly weathered soils, with mainly 1:1 type (kaolinitic) clays contained significant amounts of native adsorbed sulphate and showed an appreciable capacity to retain added sulphate. Weakly weathered soils from volcanic parent materials contained low levels of native adsorbed sulphate but had a greater capacity to adsorb added sulphate than did the “sedimentary” soils. The more weathered “volcanic” soils showed very high levels of native adsorbed sulphate and very high sulphate-retention capacities....