Phosphate Desorption from Soils and Sediments with Varying Levels of Extractable Phosphate1
- Tom O. Oloya and
- T. J. Logan2
Desorption of P from soils and sediments was studied using sequential (10-cycle) batch equilibration in 0.01M CaCl2 for equilibration periods of 2, 60, 480, 1,440, and 5,760 minutes. Soils with high Bray P1-extractable P contained a pool of easily desorbable P which was depleted by the fifth cycle. Stream suspended sediments, bottom sediments, and soils low in Bray-extractable P released small, but constant, amounts of P. Desorption of P from high extractable P soils was independent of equilibration time for the first two equilibrations, but obeyed first-order kinetics for the subsequent eight extractions. Phosphate desorbed from all soils and sediments was highly correlated with Bray P1-extractable P. The sediments and Hoytville soils from Defiance County, Ohio, gave a linear relationship between Bray P1 and desorbable P, while the Hoytville soils from the tillage study gave a quadratic increase in desorbed P with increasing Bray P1-extractable P.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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