有机酸对石灰性潮土有机磷组分的影响

采用小麦盆栽试验的方法,研究了有机酸对石灰性潮土有机 P 组分含量及土壤 P 有效性的影响.结果表明:石灰性潮土的 4 种有机 P 组分中,以中度活性有机 P 为主,其次为高稳性有机 P 和中稳性有机 P ,活性有机P的含量最低;施用磷酸二氢钾和氟磷灰石后,土壤有机P总量和有机P各组分发生了变化;土壤经有机酸处理后,有机P总量增加,有机P总量的增加主要是中度活性有机P和活性有机P的增加.而中稳性有机P和高稳性有机P主要表现为下降,说明有机酸能够促进土壤有机P由有效性较低的形态逐步向有效性高的形态转化,从而进一步矿化为无机P或者被植物根系直接吸收,其中草酸的作用效果总体上较腐殖酸强;在P素供应不足的情况下,有机酸(草酸和腐殖酸)能够提高石灰性潮土中P的有效性,促进植物的正常生长.

Effects of Organic Acids on Organic Phosphorus Fractions in Calcareous Soil

The effects of organic acids on organic phosphorus fraction in calcareous soil were studied by pot experiments. The results indicated that: the middle-labile organic phosphorus was dominant in the organic phosphorus fraction in calcareous soil, followed by the high-stable organic phosphorus and the middle-stable organic phosphorus, while the labile organic phosphorus was the lowest; the application of phosphate fertilizers (potassium dihydrogen phosphate and fluoraoatite) caused the changes of organic phosphorus content and its fraction in the tested soil; the content of organic phosphorus increased after organic acids were applied to the tested soil, which mainly attributed to the increases of the middle-labile organic phosphorus and the labile organic phosphorus, but the contents of the middle-stable organic phosphorus and the high-stable organic phosphorus decreased; organic acids promoted the activity or the bioavailability of soil organic phosphorus, thus accelerated organic phosphorus to be mineralized to inorganic phosphorus or directly absorbed by plant root system. The effect of oxalic acid in this aspect was generally stronger than that of humic acid. Under phosphorus stress, organic acids increased the phosphorus availability in calcareous soil and prompt the crop growth.