Landscape Position and Particle-size Effects on Soil Phosphorus Distributions
1987
Day, L. D. | Collins, M. E. (Mary Elizabeth) | Washer, N. E.
The objectives of this study were to investigate the effects of pedogenesis and landscape position on (i) the association of total P with particle-size content and with various particle-size separates, (ii) relative abundance of different forms of P, and (iii) P distributions between horizons and soils representing five landscape positions on an Ultisol hillslope in northwest Florida. Total-P content in soil seemed to be directly associated with the amount of clay in the lower landscape positions. This association may be the result of the activity of the mineralogy dominant in the clay fraction. Total P in the clay and P-fraction values indicated that some P had been redistributed between horizons and possibly between soils on the landscape. Coarser sands commonly had more total P than finer sand fractions. The sand fractions were composed primarily of quartz and ironstone. The amount of ironstone in the sand fraction was probably responsible for the amount of total P. Among P fractions, a large portion of P was in the residual form, especially in lower horizons, implying that the soils are intensely weathered or developed from parent materials that contained considerable residual-P, which was occluded in sesquioxides prior to deposition of the sediments. The P forms were present in the order of decreasing abundance as residual-P, Fe-P, Al-P, and Ca-P. Water-soluble P was not detected in any of the soils.
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