Forty-five acid sulfatc topsoil samples (depth < 0.5 m) from 15 soil coreswere collected from 11 locations along the New South Wales coast, Australia. There was an overalltrend for the concentration of the HCl-extr...Forty-five acid sulfatc topsoil samples (depth < 0.5 m) from 15 soil coreswere collected from 11 locations along the New South Wales coast, Australia. There was an overalltrend for the concentration of the HCl-extractable P to increase along with increasing amounts oforganic C and the HCl-extractable trivalent metals in the topsoils of some less-disturbed acidsulfate soils (pH < 4.5). This suggests that inorganic P in these soils probably accumulated viabiological cycling and was retained by complexation with trivalent metals or their oxides andhydroxides. While there was no clear correlation between pH and the water-extractable P, theconcentration of the water-extractable P tended to increase with increasing amounts of theHCl-extractable P. This disagrees with some established models which suggest that the concentrationof solution P in acid soils is independent of total P and decreases with increasing acidity. Thehigh concentration of sulfate present in acid sulfate soils appeared to affect the chemical behaviorof P in these soil systems. Comparison was made between a less disturbed wetland acid sulfate soiland a more intensively disturbed sugarcane acid sulfate soil. The results show that reclamation ofwetland acid sulfate soils for sugarcane production caused a significant decrease in theHCl-extractable P in the topsoil layer as a result of the reduced bio-cycling of phosphorusfollowing sugarcane farming. Simulation experiment shows that addition of hydrated lime had noeffects on the immobilization of retained P in an acid sulfate soil sample within a pH range3.5～4.6. When the pH was raised to above 4.6, soluble P in the soil extracts had a tendency toincrease with increasing pH until the 15th extraction (pH 5.13). This, in combination with the poorpH-soluble P relationship observed from the less-disturbed acid sulfate soils, suggests that solubleP was not clearly pH-dependent in acid sulfate soils with pH < 4.5.展开更多
文摘Forty-five acid sulfatc topsoil samples (depth < 0.5 m) from 15 soil coreswere collected from 11 locations along the New South Wales coast, Australia. There was an overalltrend for the concentration of the HCl-extractable P to increase along with increasing amounts oforganic C and the HCl-extractable trivalent metals in the topsoils of some less-disturbed acidsulfate soils (pH < 4.5). This suggests that inorganic P in these soils probably accumulated viabiological cycling and was retained by complexation with trivalent metals or their oxides andhydroxides. While there was no clear correlation between pH and the water-extractable P, theconcentration of the water-extractable P tended to increase with increasing amounts of theHCl-extractable P. This disagrees with some established models which suggest that the concentrationof solution P in acid soils is independent of total P and decreases with increasing acidity. Thehigh concentration of sulfate present in acid sulfate soils appeared to affect the chemical behaviorof P in these soil systems. Comparison was made between a less disturbed wetland acid sulfate soiland a more intensively disturbed sugarcane acid sulfate soil. The results show that reclamation ofwetland acid sulfate soils for sugarcane production caused a significant decrease in theHCl-extractable P in the topsoil layer as a result of the reduced bio-cycling of phosphorusfollowing sugarcane farming. Simulation experiment shows that addition of hydrated lime had noeffects on the immobilization of retained P in an acid sulfate soil sample within a pH range3.5～4.6. When the pH was raised to above 4.6, soluble P in the soil extracts had a tendency toincrease with increasing pH until the 15th extraction (pH 5.13). This, in combination with the poorpH-soluble P relationship observed from the less-disturbed acid sulfate soils, suggests that solubleP was not clearly pH-dependent in acid sulfate soils with pH < 4.5.
