温度变化对磷在水稻土肥际微域中迁移和转化的影响

以湖北潜江水稻土为研究对象，研究了温度变化对所施磷肥在水稻土肥际微域迁移转化的影响。实验采用室内土柱培养法，将磷酸二氢铵单施或与草酸配施后置于5℃、20℃和35℃的温度条件下，分别培养60 d或120 d后，对水稻土肥际微域内水溶性磷、有效磷及酸溶性磷的含量和分布进行了研究。结果表明：不同形态磷在水稻土肥际微域中的迁移距离均较短，单施磷酸二氢铵在5℃和20℃下肥际微域中不同形态磷迁移距离相近，均为50 mm左右，培养时间延长对迁移距离无显著影响，但在这两种培养温度下配施草酸时随着培养时间的延长，磷的迁移距离有所增加。当温度进一步升高至35℃时，配施草酸与否磷的迁移距离均比中低温条件下迁移距离减小，仅为42.5 mm左右。肥际微域中水溶性磷、有效磷和酸溶性磷含量均随着距施肥点距离的增加而显著降低。随着培养温度的升高，肥际微域水溶性磷和有效磷含量和累积量逐渐减少，但酸溶性磷含量基本呈增加趋势。同一温度下，随培养时间延长，各形态磷含量和累积量也逐渐减少。不同温度下配施草酸均能增加肥际微域内水溶性磷和有效磷的累积量。但是随着温度升高，配施草酸与否施磷后肥际微域水溶性磷和有效磷含量和累积量均有显著下降，表明温度升高施入土壤的磷的有效性下降，配施草酸对于减缓升温对磷的固定没有明显影响，但是同一温度下配施草酸可以增加肥际微域水溶性磷和有效磷的含量和累积量。肥际微域可以作为研究磷肥施入土壤后迁移转化及有效性变化的窗口，但是肥际微域中磷的变化对土体磷植物有效性的影响程度还需要进一步通过小区或大田试验进行研究。

Effect of Temperature Variation on the Transference and Transformation of Phosphorus in the Fertisphere of A Paddy Soil from Central China

The effect of temperature variation was researched on the transference and transformation of phosphorus from phosphate fertilizer in the fertisphere of a paddy soil from Hubei Province, Central China. The soil column incubation experiment was conducted with ammonium dihydrogen phosphate （MAP）, and MAP together with oxalic acid （MAP＋OA） incubated in the paddy soil at 5℃, 20℃, and 35℃ for 60d and 120d. When the incubation experiment finished, the contents and distribution of water-extractable P, Olsen P, and HCl-extractable P were determined. The results showed that the transference distances were very short for all P forms in the fertisphere of paddy soil. At 5℃ and 20℃, only 50 mm of transference distance for P forms were observed in the MAP treatment, and which did not changed when the incubation time was prolonged. But at the same temperatures, with the increase of incubation period the transference distances were increased when OA was co-applied with MAP. When the temperature was increased to 35℃, the transference distances of P forms from MAP with or with no OA co-application were only 42.5 mm, shorter than those at the low or middle temperatures. The contents of water-extractable P, Olsen P, and HCl-extractable P were decreased with the increase of the distance from fertilization site. With the increasing of incubation temperature, the contents and amounts of water-extractable P or Olsen P were reduced, while that of HCl-extractable P seemed to be increased. With the incubation period prolonging, the contents and amounts of P forms were decreased at the same temperature. The co-application of OA could be beneficial to increase the amounts of water-extractable P and Olsen P in the fertisphere at all the temperatures studied. With the temperature rising, the contents and amounts of water-extractable P and Olsen P were significantly reduced in the fertisphere of paddy soil and P fertilizers with or without OA together. It indicated that the availability of P applied into soil declined with