不同土壤磷的固定特征及磷释放量和释放率的研究

CHARACTERISTICS OF FIXATION AND RELEASE OF PHOSPHORUS IN THREE SOILS

通过加入不同浓度的P(水土比为 2 0∶1 )并利用连续提取法 ,对三种土壤P的固定特征以及磷的释放进行了研究。结果表明 ,红壤对P的固定能力高于潮土 ,而潮土高于水稻土 ,在加入P量为 2 97gkg- 1土壤的条件下 ,三种土壤对P的固定量分别为 2 84gkg- 1、2 5 3gkg- 1和 2 0 8gkg- 1。三种土壤对P的固定率则随着加入P量的增加而降低。在P的释放研究中 ,随着提取次数的增加 ,P的释放量减少 ,并在提取 8次后 ,以后各次P的释放量不发生显著变化。三种土壤中 ,水稻土P的最大释放量 (1 2 4 0 7mgkg- 1)显著高于红壤 (60 46mgkg- 1)和潮土 (1 9 74mgkg- 1) ,水稻土P的总释放量 (1 6次 )也大于红壤和潮土 ,三种土壤P的总释放量分别为 2 0 6 0 2 (1 98gkg- 1土壤P处理 )和 2 71 91mgkg- 1(2 97gkg- 1土壤P处理 )、1 0 0 48和2 60 5 3mgkg- 1、1 1 6 0 6和 1 3 1 91mgkg- 1。三种土壤P的释放率随着提取次数的增加而增加 ,并逐渐达到稳定。水稻土的释放率显著高于红壤和潮土。水稻土和潮土中 ,1 98gkg- 1土壤P处理的土壤P的释放率高于2 97gkg- 1土壤P处理的土壤 。

In this experiment, characteristics of phosphorus fixation and release were studied with added different concentrations of P (water∶ soil is 20∶1) and by sequential extraction. The results showed that, fixing P capacity of red soil is higher than that of fluvo-aquic soil, and fixing P capacity of paddy soil is lowest among three soils. Fixing P capacities of three soils are 2.84 g kg -1, 2.53 g kg -1 and 2.08 g kg -1 soil under treatment of P 2.97 g kg -1 soil. Ratio of P fixed to P added reduces with increase of added P. In release experiment, capacities of P release reduce with increase of extracting times, and change insignificantly after 8 times of extraction. In three soils, maximum of P release of paddy soil (124.07 mg kg -1) is higher than that of red soil (60.46 mg kg -1)and fluvo-aquic soil (19.74 mg kg -1), the similar results were obtained in total amount of P released. At the beginning of experiment, the ratio of P released to P fixed increases gradually and then reaches equilibrium with increase of extracting times, and that of P released in paddy soil is higher significantly than that of red and fluvo-aquic soils. Ratio of P released to P fixed of soils treated with 1.98 g P kg -1 soil is higher than that of soils treated with 2.97 g P kg -1 soil in paddy and fluvo-aquic soils, but the contrary result was obtained in red soil.