Releasing Pattern Of Applied Phosphorus And Distribution Change Of Phosphorus Fraction In The Acid Upland Soils With Successive Resin Extraction
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Releasing Pattern of Applied Phosphorus and Distribution Change of Phosphorus Fractions in the Acid Upland Soils with Successive Resin Extraction (A. Hartono): The releasing pattern of applied P in the acid upland soils and the soil properties influencing the pattern were studied. Surface horizons of six acid upland soils from Sumatra, Java and Kalimantan were used in this study. The releasing pattern of applied P (300 mg P kg'l) of these soils were studied by successive resin extraction. P fractionation was conducted to evaluate which fractions released P to the soil solution after successive resin extraction. The cumulative of resin-Pi (Pi) release of soils was fitted to the first order kinetic. Regression analysis using factor scores obtained from the previous principal components analyses was applied to determine soil properties influencing P releasing pattern. The results suggested that the maximum P release was significantly (P < 0.05) increased by acidity plus 1.4 om mineral-related factor (PCl) i.e. exchangeable Al and 1.4 om minerals (smectite and vermiculite) and decreased by oxide related factor (PCI) i.e. aluminum (AI) plus 112 iron (Fe) (by ammonium oxalate), crystalline Al and Fe oxides. cation exchange capacity. and clay content. P fractionation analysis after successive resin extraction showed that both labile and less labile in the form of NaHCO-Pi and NaOH-Pi fractions, respectively, can be transformed into resin-Pi when in the most labile resin-Pi is depleted. Most of P released in high oxides soils were from NaOH-Pi fraction while in low oxides soils were from NaHC01-Pi. P release from the former fraction resulted in the maximum P release lower than that of the latter one. When NaHCOJ-Pi was high, NaOH-Pi was relatively more stable than NaHCOJ-Pi despite resin-Pi removal. NaHCOJ-Pi and NaOH-Pi are very important P fractions in replenishing resin-Pi in these acid upland soils.