The Effect of Fertilizer Phosphorus on Labile Phosphorus in Soils of Varying Sorption Capacities

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Bekunda M.A
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It has been shown (Bekunda, 1987) that substantial amounts of fertilizer phosphorus (P) (>20%) could still be present in some soils in resin extractable torms (labile P) two years After application. Larsen et al. (1965) measured the rate of P immobilization in terms of the time in years required for half of the applied P to become non-labile. There was no obvious relationship between the half-life values and soil properties normally associated with the adsorption complex (e.g. clay, organic matter content, nri extractable AI and Fe). This would appear to conflict with the general experience that the residual effectiveness of P is least on very highly buffered soils and greatest on weakly buffered soils (Anderson and McLachlan, 1951 and Hughes and Searle, 1964). Movement of P has been attributed to the nature of soil as it relates to the chemical reactions that occur in the soil (Logan and McLean, 1973).
East African Agricultural And Forestry Journal, 55 (4), p. 219-226