水分管理对太湖地区水稻土无机磷转化的影响

采用中性土无机磷分级方法,研究不同水肥条件下水稻土无机磷动态变化及其影响因素,结果表明:施磷处理明显提高了各形态无机磷含量,在淹水培育条件下,Ca2-P、Ca8-P、Al-P逐步降低,Fe-P、Oc-P呈增高趋势,Ca10-P基本保持稳定;各种形态的磷在60%田间持水量培育下变化类似。总体而言,土壤培育增加了对磷的固定作用,且MNK、MNPK、CNPK处理较C0和CNK效果更明显。培育期内土壤晶质铁、络合铁及无定形铁含量的变化符合土壤无机磷转化的部分机制,至于还原铁在淹水条件下如何再次氧化而导致磷的二次固定需要进一步研究。

Effect of Water Management on Transformation of Inorganic Phosphorus in Paddy Soil in Taihu Lake District

The dynamic changes of inorganic phosphorus in paddy soil and its influential factors under different water and fertilizer conditions were studied by using classification method for inorganic phosphorus in neutral soil.The results indicated that the phosphorus application could significantly increase various forms of inorganic phosphorus content.Under the waterlogged condition,the contents of Ca2-P,Ca8-P and Al-P were gradually decreasing,while the contents of Fe-P and Oc-P were increasing,and the content of Ca10-P was basically stable.The changing trends of all forms of phosphorus content were similar in the 60% field water-holding incubation.In a word,soil incubation increased the fixation ability of soil to phosphorus,and the MNK,MNPK and CNPK treatments fixed more P than C0 and CNK treatments.The changes in the contents of soil crystalloid Fe,chelated Fe and amorphous Fe in the incubation period corresponded with the partial mechanism of soil inorganic phosphorus transformation,but how the reducing iron in the waterlogged soil was oxidized and led to the second fixation of phosphorus still needed further study.