Soil Characteristics and Management Effects on Phosphorus Sorption by Highland Plateau Soils of Ethiopia
- Miressa Dufferaa and
- Wayne P. Robarge *a
Differences in crop and fertilizer management are known to influence P retention by soils. An experiment was conducted to study the effect of soil characteristics and management practices on P sorptoin behavior of the highland plateau soils of Ethiopia. Surface samples from two Vertisols, an Andisol, and an Alfisol were collected from farmers' fields, research station farms, and from non-cultivated-non-fertilized areas. Phosphorus sorption data were obtained by equilibrating 3-g soil samples in 30 mL of 0.01 M CaCl2 containing various amounts of KH2PO4 Inorganic P fractions were determined by the Hedley P fractionation scheme. There was little variation in P sorption among Vertisol samples of alluvial origin as a result of cultivation-fertilization practices. For soils of volcanic origin (Vertisol2 and Andisols), and the Alfisol, samples collected from farmers' fields sorbed more P than the non-cultivated and research station samples. Least amounts of applied P sorbed by the non-cultivated Andisol samples reflect the relatively large amounts of resin extractable P initially present in these soils and demonstrate that labile P initially present in the soil can influence subsequent P sorption. Stepwise regression analysis of the P sorption data showed that resin P accounts for 81% of the variation in P sorption at 0.2 mg P L−1 in solution. The highest amount of P was sorbed by samples collected from farmers' fields and was mainly due to the practice of continuous cropping with minimal P fertilization, which depletes labile P, and therefore requires higher levels of P fertilization for optimum crop yield.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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