Soil P status, inorganic P fractions, and P sorption properties were studiedusing sandy fluvo-aquic horticultural soils, which are high in organic matter content for vegetableproduction in comparison with a soil used ...Soil P status, inorganic P fractions, and P sorption properties were studiedusing sandy fluvo-aquic horticultural soils, which are high in organic matter content for vegetableproduction in comparison with a soil used for grain crop production in Zhengzhou, Henan Province,China P fractions, Olsen-P, and OM were determined at different depths in the soil profile andsorption isotherm experiments were performed Most P in excess of plant requirements accumulated inthe topsoil and decreased with soildepth. Total P, inorganic P, and OM concentrations increased withcontinued horticultural use Olsen-P concentrations in the 0-20 cm depth of horticultural soils were9 to 25 times higher than those of the grain crop soil. A linear transformation of the Langmuirequation showed that the P adsorption maximum (491.3 mg P kg^(-1)) and the maximum phosphatebuffering capacity (162.1 L kg^(-1)) for 80--100 cm were greater in the grain crop soil than thehorticultural soils. Thus, the most immediate concern with excess P were in areas where heavy Pfertilizer was used for vegetable crops and where soil P sorption capacities were low due to sandysoils and high organic matter content.展开更多
Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley＇s extraction was used to separate soil phosphorus （P） into inorganic Pi （ge...Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley＇s extraction was used to separate soil phosphorus （P） into inorganic Pi （geochemical） and organic Po （biological） fractions. Direct extractable P by Olsen （Olsen-P）, by Mehlich llI （M3-P） and by ammonium oxalate （Pox） was also determined. Phosphorus sorption was carried out with 1：10 soil/solution ratio and sorption parameters were derived from the Langmuir model to the experimental data. Most of the total P occurred in inorganic P forms （74% of Pt）, while organic P comprised only 26% of the Pt. Among the various inorganic P forms relatively large amount of residual P （111 mg kg^-1） was observed, while occluded P in calcium phosphate minerals （d.HCI-Pi） and in Fe, Al-oxides （c.HCI-Pi） existed in equal amounts （83.1 and 83.7 mg kg^-1 respectively）. The phosphorus sorption parameters showed positive relationships with clay content, cation exchange capacity and the sum of exchangeable calcium plus magnesium. Overall, this study indicated that Ca and Mg compounds strongly influence the P chemistry in moderately weathered soils, with relatively high concentration of primary P minerals.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 40071053 and 40078055).
文摘Soil P status, inorganic P fractions, and P sorption properties were studiedusing sandy fluvo-aquic horticultural soils, which are high in organic matter content for vegetableproduction in comparison with a soil used for grain crop production in Zhengzhou, Henan Province,China P fractions, Olsen-P, and OM were determined at different depths in the soil profile andsorption isotherm experiments were performed Most P in excess of plant requirements accumulated inthe topsoil and decreased with soildepth. Total P, inorganic P, and OM concentrations increased withcontinued horticultural use Olsen-P concentrations in the 0-20 cm depth of horticultural soils were9 to 25 times higher than those of the grain crop soil. A linear transformation of the Langmuirequation showed that the P adsorption maximum (491.3 mg P kg^(-1)) and the maximum phosphatebuffering capacity (162.1 L kg^(-1)) for 80--100 cm were greater in the grain crop soil than thehorticultural soils. Thus, the most immediate concern with excess P were in areas where heavy Pfertilizer was used for vegetable crops and where soil P sorption capacities were low due to sandysoils and high organic matter content.
文摘Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley＇s extraction was used to separate soil phosphorus （P） into inorganic Pi （geochemical） and organic Po （biological） fractions. Direct extractable P by Olsen （Olsen-P）, by Mehlich llI （M3-P） and by ammonium oxalate （Pox） was also determined. Phosphorus sorption was carried out with 1：10 soil/solution ratio and sorption parameters were derived from the Langmuir model to the experimental data. Most of the total P occurred in inorganic P forms （74% of Pt）, while organic P comprised only 26% of the Pt. Among the various inorganic P forms relatively large amount of residual P （111 mg kg^-1） was observed, while occluded P in calcium phosphate minerals （d.HCI-Pi） and in Fe, Al-oxides （c.HCI-Pi） existed in equal amounts （83.1 and 83.7 mg kg^-1 respectively）. The phosphorus sorption parameters showed positive relationships with clay content, cation exchange capacity and the sum of exchangeable calcium plus magnesium. Overall, this study indicated that Ca and Mg compounds strongly influence the P chemistry in moderately weathered soils, with relatively high concentration of primary P minerals.
