不同生境酸化背景下铁、铝氧化物对磷有效性的调控及机理研究

The iron and aluminum (hydr)oxides are very important fractions in the soil fixation capacity for phosphorus. Iron and aluminum (hydr)oxides affect P availability in the soils, whether newly phosphorus fertilizer or old phosphorus fertilizer. It is well known that low P availability in the soils would seriously affect crop normal growth and yield. In a real situation, stopping the soil acidification would be extremely difficult, at the same time, low P fertilizer utilization rate and the price of P fertilizer increased are inevitable. Questions remain, however, the study deals with the interaction between P, iron and aluminum (hydr)oxides, regulating mechanism of iron and aluminum (hydr)oxides on P availability in the background of acidification and different habitats is still weakness. Based on the unsolved questions mentioned above, this project selects red soil which extensively spreads in the South of China as tested soil, and the following experimental methods are used: indoor culture, solution culture and soil culture. Our specific objectives for this project are to dedicate the following researches in the different habitats. 1) effect of soil acidification on iron, aluminum oxide (crystal, amorphous)in the different habitats; 2) effect of soil acidification on P availability; 3) interaction and mechanisms of iron, aluminum oxide and P in the process of soil acidification; 4) effect of soil acidification and P fertilizer usage on rice and rape growth and physiological character. In this project, it is intended to uncover mechanisms of interaction of iron, aluminum oxide and P, and influence of iron, aluminum oxide on P availability in the background of soil acidification and different habitats from different aspects. It also means to provide theoretic basis and direction for application P fertilizer reasonable in the acid soil.

土壤中铁、铝氧化物对磷有强烈的固定作用，影响新施入和已存在于土壤中磷素的生物有效性，低的磷有效性将严重影响作物正常生长和产量。现实中，土壤酸化很难遏制，磷肥利用率低且磷肥价格上涨不可避免，而不同生境酸化背景下磷、铁氧化物、铝氧化物交互作用及磷有效性受铁、铝氧化物影响调控机制的研究尚显薄弱。本项申请将以红壤为研究对象，采用室内培养、水培、土培试验相结合的方法，研究不同生境条件下（氧化、还原），酸化对铁、铝氧化物（结晶态、无定形）的影响；酸化对磷有效性的影响；酸化过程中铁、铝氧化物、磷的交互作用及机理；酸化和磷肥用量对水稻、油菜生长及生理性状的影响。旨在从不同角度揭示不同生境条件下，酸化过程中铁、铝氧化物对磷有效性的影响及作用机理，意欲为酸化过程中合理制定酸性土壤磷肥管理技术措施提供理论依据。

土壤酸碱性是土壤众多化学性质的综合反应，分为自然酸化和人为酸化。长江以南地区雨水充沛，土壤风化强烈，且富含铁、铝氧化物，常年经历着氧化、还原交替过程，上述因素均为影响土壤磷有效性的重要因素，在此背景下研究土壤磷有效性，具有重要的理论和现实意义。.本研究以红壤为试验材料，研究了酸化强度、酸化时间对磷有效性、铁氧化物形态变化的影响及磷有效性与铁氧化物形态变化的关系。结果表明，试验土壤经3天，6天，9天，15天，不同pH(3.6，4.5，5.6)酸液浸泡后，pH值降低、酸化时间增加，促进速效磷的释放；pH值降低对铁氧化物形态变化影响不显著；酸化时间增加铁氧化物形态发生变化，游离氧化铁、无定形氧化铁二种形态铁氧化物呈此消彼长的关系，二者显著、极显著负相关。速效磷与无定形氧化铁正相关，而与游离氧化铁负相关。表明当土壤存在渍水还原情况时，无定形的磷酸铁化合物可以作为一种有效磷源。.评价土壤磷有效性常用的农艺指标是Olsen P，常用的评价磷环境效应的指标为磷吸附饱和度。当用二个指标同时评价土壤磷素状况时，二者有交集，磷吸附参数与Olsen P从环境和农业生产需求二方面说明土壤磷素丰缺状况，既兼顾了农业生产需求也兼顾了环境保护问题。