中文摘要：

土壤有效磷含量低是影响作物生产的重要限制因素之一．作物根分泌活化难溶性磷的有机酸对改善其磷素营养具有重要意义．采用张守敬和Jackson,S；机磷分级方法，以湖北省武昌土为材料，加入不同磷源和有机酸，经室温培养后，测定速效磷含量和无机磷组分．结果表明，有机酸引起速效磷含量增多，除苹果酸处理的变化较小外，草酸和柠檬酸的加入使土壤中速效磷显著增加．供试有机酸均使土壤铝磷（Al-P）含量下降，钙磷（Ca-P）含量上升，变幅大小依次为草酸处理〉柠檬酸处理〉苹果酸处理；有机酸活化的磷主要来源于土壤中Al-P和铁磷（Fe-P）中的磷，同时有机酸能够促进土壤中闭蓄态磷（0．P）的形成与积累．图1表3参30

英文摘要：

Low content of available phosphorus in soil is one of the major limitations to crop production. Mobilization of insoluble phosphates by root exudates plays an important role in improving P nutrition of crops. The soil samples collected from Hubei, China were tested to analyze their inorganic phosphorus fractions and available P after incubated with added various phosphorus sources and organic acids. The results indicated that organic acids, except malic acid, had significant influence on available P. Application of organic acids decreased the content of A1-P and increased that of Ca-P, in the order of oxalic acid 〉 citric acid 〉 malic acid. Phosphorus was activated by organic acids mostly from the fractions of AI-P and Fe-P, and organic acids accelerated formation and accumulation of O-P in soil. Fig 1, Tab 3, Ref 30