摘要
以湖南省发育于第四纪红土母质上的耕型红壤及其由这类红壤发育而成的水稀土为材料,用恒温吸附试验等方法研究了旱改水对土壤磷的吸持特性的影响以及控制土壤对磷的吸持特性变化的土壤因素,结果表明,在供试起始磷浓度范围内,红壤性水稻土对磷的吸持容量和吸持强度都大于耕型红壤;引起这一变化的主要原因是由于旱改水后,土壤水分状况的变化引起土壤中氧化铁的活性增强所致。
Phosphate retention characteristics and the controlling factors ofphosphate retention characteristics of the paddy soil and arable red earth de-veloped from the Qutaernary Red Clay in Hunan Province were studied with phos-phate absorption isotherm and statistical analysis. The results are presentedas follows. a. Phosphate retention data of both the paddy soil and arable red earthin the initial concentration range of 0~40 ppm P fitted well in with the One-surface Langmuir, Freundlich, and Temkin Equations, of which the One-surface Lanmuir Equation fitted in best. The Correlations between thephosphate retention data and the three equations are all very significant at0.01 level. b. In the initial phosphate concentration range, phosphate retention ca-pacity and intensity of paddy soil characterized by One-surface Langmuir Para-meters q_m and K are larger than that of arable red earth. Among the paddysoils, that of the paddy soils with early rice-late rice-winter flooding Systemare larger than that of the paddy soils with early rice-late rice-green manureand early rice-late rice-rape systems. c. The main foctor of controlling phosphate retention characteristics of thetested soils is free iron oxide in soils, especially the amorphous iron oxide of it.The maximum phosphate adsorption (q_m) in One-surface Langmuir Equation iscorrelated with amorphous iron oxide content at 0.01 significant level. Afterthe removal of free iron oxide and amorphous iron oxide, phosphate retentioncapacity of the tested soils decreased by 57~76% and 26~60%, respectively.
关键词
水稻
耕作土壤
红壤
磷
Krasnozem
Arable Soil
Paddy soil
Phosphorus
