不同熟化度红壤稻田磷的吸附和解吸特征初探

取熟化度不同的３种红壤性水稻土进行室内模拟培养，考察施磷后土壤对磷的吸附和解吸动态，同时比较了不同施磷量及不同培养温度条件下各供试红壤性水稻土对磷的吸附差异。结果表明：熟化度不同，对磷的吸附表现出随熟化度提高，吸磷比下降的明显规律，经９６ｈ培养后，初度熟化红壤水稻土吸附量高达９３％；中度熟化的为４３％；高度熟化的降低至２３．１％。被吸附固定的磷在初度和中度熟化红壤性水稻土中都很难解析出来，只有高度熟化的可解析出一部分。不同施磷浓度比较，以低浓度施磷处理的吸磷量普遍高于高浓度施磷处理，４０℃条件下培养的吸磷量明显高于２０℃条件下培养。上述磷的吸附和解吸特征随熟化度的变化主要与熟化过程中有机质含量增加，活性铁、铝含量明显下降有关。

Study on P Sorption and Desorption Characters of Different Mellow Red Paddy Soils

Laboratory incubation experiment using three red paddy soils with different mellow stage was conducted to investigate the kinetic of P sorption and desorption of soils after P application, also investigate the effect of different P rate and temperature on P sorption by red paddy soil. The results indicated that the P sorption obviously decreaseed with the increasing of soil mellow stage, after 96 hours inculbation, the amount of P sorption for initial mellowing stage soil was up to 93%, it was 43% for medium mellowing soil. it further declined to 23.1% for ample mellowing soil. the P absorbed after application in initial and medium mellowing soils was difficult to be desorpted, only in ample mellowing soil, there was small part of P to be desorpted during incubation. Comparing with different rate of P application, P sorption in low rate treatemnt was generally higher than it in high rate treatment, also P sorption in condition of 40℃ was obviously higher than it in 20℃. Above charecteristics of P sorption and desorption in red soil is related to the increasing of organic matter and the decreasing of free iron and alumilum onides during the period of soil mellowing.