持续淋溶条件下有机酸对土壤磷素释放及无机磷组分的影响

Effects of Low-molecular-weight Organic Acids on Release of Soil Phosphorus and Inorganic Phosphorus Fractions in Continuous Leaching Condition

采用土柱模拟试验,研究了柠檬酸、草酸和乙酸在持续淋溶条件下土壤磷的动态释放特征及淋溶前后无机磷组分的变化情况。结果表明:相同浓度条件下三种有机酸对供试土壤磷的活化能力大小顺序为:柠檬酸>乙酸>草酸,且不同有机酸淋溶过程中磷的释放特征各不相同。乙酸的最大释磷量及释磷率虽不及其它有机酸处理,但表现出了较好的持续活化能力。持续淋溶条件下,三种有机酸均能显著地活化土壤无机磷,其中柠檬酸和乙酸处理对无机磷的活化效果较好,草酸相对较弱,且有机酸的淋溶使土壤磷素形态构成发生变化;柠檬酸和乙酸作用下各形态无机磷变化率大小顺序为:Ca-P>Fe-P>Al-P>O-P;草酸处理下变化率顺序为:Ca-P>Al-P>O-P>Fe-P,说明三种有机酸对Ca-P的活化最为明显,其次为Fe-P或Al-P,而O-P在淋溶前后变化很小。

A soil column leaching experiment was conducted to investigate the effects of citric acid, oxalic acid and acetic acid on release characteristics of phosphorus and the inorganic phosphorus fractions. The results showed that the ability order of three organic acids on activating soil phosphorus was citric〉oxalic〉acetic acid. Different treatments resulted in though the different release characteristics of phoshorus. The acetic acid showed a relatively strong sustainability, highest release amount and rate of P of acetic acid were significantly lower than other organic acid treatments. During the continuous leaching, all the three organic acids could significantly activate the inorganic phosphorus. The activation effects of citric acid and acetic acid were better than oxalic acid, and the effect of organic acids could change the structure of inorganic phosphorus. The rate of variation on inorganic phosphorus fractions by citric acid and acetic acid was followed the order of Ca-P〉Fe-P〉Al-P〉O-P, while the rate of variation by oxalic acid was followed the order of Ca-P〉Al-P〉O-P〉Fe-P. These results indicated that the activation effect of the three organic acid on Ca-P was the most obvious, the second obvious was Fe-P or AI-P, while O-P little changed.