低分子量有机酸对石灰性潮土无机磷形态转化的影响

无菌培养条件下,模拟缺磷胁迫时植物根系分泌的低分子量有机酸种类和数量,采用石灰性土壤无机磷分级方法,研究了低分子量有机酸对石灰性潮土无机磷形态转化的影响。结果表明:①在石灰性潮土中无机磷主要以有效性较低的磷酸钙盐(Ca10-P等)形式存在,而有效性较高的形式(Ca8-P等)含量较少,Ca2-P就更少。②有机酸通过结合土壤中可以使磷固定的Ca、Fe及Al,致使根际范围酸化,促进磷酸盐的形态转换,增加磷的有效性。这种促进能力因有机酸种类和性质的不同而异,其促进能力大小顺序为草酸>柠檬酸>酒石酸。

Influence of Low Molecular Weight Organic Acid on Conversion of Inorganic Phosphorus in Calcareous Alluvial Soil

Under the abacterial condition, the influence of low molecular weight organic acids(LMWOA) on the conversion of inorganic phosphorus in calcareous alluvial soil was studied by simulating the sorts and concentrations of LMWOA secreted by plant roots using the method of inorganic phosphate fractionation. The results showed that ① the majority of inorganic phosphorus was the less available calcium phosphate (Ca(10)-p etc.) in calcareous alluvial soil. The content of available components (Ca8-p etc.) were low and that of Ca2-p even lower; ② organic acids could convert the unavailable inorganic phosphorus into available form because they absorbed the substances such as Ca, Fe and Al, which can fix phosphorus, and made the rhizosphere acidified. The ability of the different organic acids to convert inorganic phosphorus components varied.The order was Oxalic acid >Citric acid >Tartaric acid.