Soil components affecting phosphate sorption parameters were studied using acid paddy soils derived from basalt, granite, sand-shale and the Pearl River Delta sediments, respectively, in Guangdong Province. For each s...Soil components affecting phosphate sorption parameters were studied using acid paddy soils derived from basalt, granite, sand-shale and the Pearl River Delta sediments, respectively, in Guangdong Province. For each soil, seven 2.50 g subsamples were equilibrated with 50 mL 0.02 mol L-1 (pH=7.0) of KCI containing 0, 5, 10, 15, 25, 50 and 100 mg P kg-1, respectively, in order to derive P sorption parameters (P sorption maximum, P sorption intensity factor and maximum buffer capacity) by Langmuir isotherm equation. It was shown that the main soil components influencing phosphate sorption maximum (Xm) included soil clay, PH, amorphous iron oxide (Feo) and amorphous aluminum oxide (Alo), with their effects in the order of Alo > Feo > pH > clay. Among these components, pH had a negative effect, and the others had a positive effect. Organic matter (OM) was the only soil component influencing P sorption intensity factor (K). The main components influencing maximum phosphate buffer capacity (MBC) consisted of soil clay, OM,pH, Feo and Alo, with their effects in the order of Alo > OM > pH > Feo > clay. Path analysis indicated that among the components with positive effects on maximum phosphate buffer capacity (MBC), the effect was in the order of Alo > Feo > Clay, while among the components with negative effects, OM > pH. OM played an important role in mobilizing phosphate in acid paddy soils mainly through decreasing the sorption immensity of phosphate by soil particles.展开更多
Silicate adsorption in eight paddy soils developed from four different parent materials in Guangdong Province, China was examined to obtain fundamental knowledge of silicate adsorption to improve the efficacy of silic...Silicate adsorption in eight paddy soils developed from four different parent materials in Guangdong Province, China was examined to obtain fundamental knowledge of silicate adsorption to improve the efficacy of silicate fertilizer use in these areas. A correlation analysis showed that silicate adsorption did not obey the Langmuir equation (r = -0.664-0.301) but did obey the Freundlich and Temkin equations (P < 0.01, r = 0.885-0.990). When the equilibrium silicate concentration (Ci) was less than 45 mg SiO2 kg-1, the adsorption capacity was in the following decreasing order of paddy soils: basalt-derived > Pearl River Delta sediment-derived > granite-derived > sand-shale-derived. Stepwise regression and path analysis showed that for the investigated paddy soils amorphous MnO and Al2O3 were the two most important materials that affected silicate adsorption. Moreover, as Ci increased, amorphous Al2O3 tended to play a more important role in silicate adsorption, while the effects of amorphous MnO on silicate adsorption tended to decrease.展开更多
基金Project supported by the Guangdong Provincial Natural Science Foundation of China! (No. 990719) the fund of the "Ninth Five-
文摘Soil components affecting phosphate sorption parameters were studied using acid paddy soils derived from basalt, granite, sand-shale and the Pearl River Delta sediments, respectively, in Guangdong Province. For each soil, seven 2.50 g subsamples were equilibrated with 50 mL 0.02 mol L-1 (pH=7.0) of KCI containing 0, 5, 10, 15, 25, 50 and 100 mg P kg-1, respectively, in order to derive P sorption parameters (P sorption maximum, P sorption intensity factor and maximum buffer capacity) by Langmuir isotherm equation. It was shown that the main soil components influencing phosphate sorption maximum (Xm) included soil clay, PH, amorphous iron oxide (Feo) and amorphous aluminum oxide (Alo), with their effects in the order of Alo > Feo > pH > clay. Among these components, pH had a negative effect, and the others had a positive effect. Organic matter (OM) was the only soil component influencing P sorption intensity factor (K). The main components influencing maximum phosphate buffer capacity (MBC) consisted of soil clay, OM,pH, Feo and Alo, with their effects in the order of Alo > OM > pH > Feo > clay. Path analysis indicated that among the components with positive effects on maximum phosphate buffer capacity (MBC), the effect was in the order of Alo > Feo > Clay, while among the components with negative effects, OM > pH. OM played an important role in mobilizing phosphate in acid paddy soils mainly through decreasing the sorption immensity of phosphate by soil particles.
基金Project supported by the Guangdong Provincial Natural Science Foundation of China (No. 021029)the President Fund of South China Agricultural University (No. 2002014).
文摘Silicate adsorption in eight paddy soils developed from four different parent materials in Guangdong Province, China was examined to obtain fundamental knowledge of silicate adsorption to improve the efficacy of silicate fertilizer use in these areas. A correlation analysis showed that silicate adsorption did not obey the Langmuir equation (r = -0.664-0.301) but did obey the Freundlich and Temkin equations (P < 0.01, r = 0.885-0.990). When the equilibrium silicate concentration (Ci) was less than 45 mg SiO2 kg-1, the adsorption capacity was in the following decreasing order of paddy soils: basalt-derived > Pearl River Delta sediment-derived > granite-derived > sand-shale-derived. Stepwise regression and path analysis showed that for the investigated paddy soils amorphous MnO and Al2O3 were the two most important materials that affected silicate adsorption. Moreover, as Ci increased, amorphous Al2O3 tended to play a more important role in silicate adsorption, while the effects of amorphous MnO on silicate adsorption tended to decrease.
