Liming and the phosphatase activity and mineralization of phosphorus in an andic soil

Abstract

Ca(OH) 2 was added under laboratory conditions to an acid soil rich in organic matter and with variable charge surfaces, and the effects on phosphatase activity and extractable P fractions were studied. During 39 days of initial incubation at room temperature (until the various limed soil samples reached the desired pH values of pH 5.5, 6.0 or 6.5), there were decreases in phosphatase activity and bicarbonate-extractable Po that were greater the greater the dose of lime; during 9 weeks of subsequent incubation at 28°C, net P mineralization that was uncorrelated with phosphatase activity occurred in all samples. In the samples limed to pH 6.5, mineralization of organic P, especially HCO − 3 Po and NaOH Po, was significantly greater than in less heavily limed and unlimed samples.