低分子量有机酸对石灰性土壤磷素形态转化及有效性的影响

采用室内培养和化学分析的方法研究了几种低分子量有机酸对石灰性土壤中磷的活化作用。结果表明:供试有机酸通过溶解、螯合等作用均能不同程度地促进合成磷酸盐的磷素释放。活化DCP、ODP、Fe-P、A l-P的能力依次为柠檬酸>草酸>苹果酸>酒石酸>乙酸;活化FA的能力是草酸>柠檬酸>苹果酸>酒石酸>乙酸。同种有机酸作浸提剂时,有机酸浓度越高磷酸盐中磷素释放量也越大。施加各种有机酸可以不同程度地降低土壤中Fe-P、A l-P和Ca10-P,增加Ca2-P、Ca8-P和O-P含量,总的趋势是促进土壤中植物难以利用的无机磷形态向有效性较高的形态转化。这种促进作用大小顺序为草酸>柠檬酸>酒石酸。

Effect of Low Molecular Weight Organic Acids on Transformation and Availability of Phosphates in Calcareous Soil

The mobilizing effects of low molecular weight organic acids(LMWOA) on several synthesized phosphates commonly occurring in calcareous soils were studied by indoor incubation and pot trial.The results showed that,the tested LMWOA could promote the phosphorus release of the phosphates(DCP,ODP,FA,Fe-P and Al-P) tested in different degrees.The mobilizing ability for DCP,ODP,Fe-P and Al-P was in the order of citric acid > oxalic acid > malic acid > tartaric acid > acetic acid,and that for FA was oxalic acid > citric acid > malic acid > tartaric acid > acetic acid.The mobilizing capacity increased with the increment of organic acid concentration.The adding of LMWOA could reduce the contents of Ca_(10)-P,Fe-P,Al-P and increase Ca_2-P,Ca_8-P,and O-P in the soil,i.e.promote the transformation from less or unavailability phosphates to more available phosphates.