四川盆地丘陵区农田土壤对磷的吸附与解吸特征

研究了四川盆地丘陵区典型水田和旱地土壤对磷的吸附与解吸特征,并讨论了吸附-解吸参数与土壤基本理化性质的关系。结果表明,不同pH的农田土壤对磷的吸附和解吸均存在显著差异,土壤对磷的吸持能力表现为中性土壤〉酸性土壤〉石灰性土壤,中性有利于土壤吸附磷;水稻土对磷的最大吸附容量（Qm）和最大缓冲容量（MBC）高于紫色土,而临界平衡磷浓度（EPC0）和解吸率（b）低于紫色土。农田土壤对磷的吸附与解吸参数还受土壤理化性质的影响,Qm和MBC与有机质含量、无定形铁（Fe-ox）含量呈极显著正相关（P〈0.01,n=6）;吸附常数（K）与有机磷含量呈显著负相关（P〈0.05,n=6）;EPC0与土壤pH、CaCO3含量呈显著负相关,与有机磷含量呈显著正相关（P〈0.05,n=6）;b与Fe-ox含量呈显著负相关（P〈0.05,n=6）。

Adsorption and Desorption Characteristics of Phosphorus on Cropland Soils in the Hilly Area of Sichuan Basin,China

Adsorption and desorption characteristics of cropland soils at different pH in the hilly area of Sichuan Basin to phosphorus were studied,and the effect of soil physicochemical properties on adsorption and desorption parameters was discussed.The results showed that the adsorption characteristics of the tested soil to phosphorus could be well described by Langmuir,Freundlich,and Temkin equations.Adsorption and desorption of the cropland soils at different pH to phosphorus indicated significant differences.The adsorption capacity showed an order of neutral,acidic and calcarous for the purple soil and paddy soil from high to low,and neutral soil was beneficial to phosphorus adsorption.The Maximum adsorption capacity（Qm） and maximum buffer capacity（MBC） of the paddy soil to phosphorus were higher than that of the purple soil,while the equilibrium concentration of phosphorus at zero sorption（EPC0） and desorption rate（b） in an inverse order.The adsorption and desorption parameters were influenced by the physicochemical properties of soil.Qm and MBC showed a positive relationship with the contents of organic matter and Fe-ox（P0.01,n=6）,while b showed a negative relationship with the content of Fe-ox（P0.05,n=6） significantly.Adsorption constant（K） showed a negative relationship with the content of organic phosphate（P0.05,n=6） significantly.EPC0 showed negative relationship with pH and CaCO3 content（P0.05,n=6） while a positive relationship with the content of organic phosphate（P0.05,n=6） significantly.Therefore,the suitable countermeasures should be put forward for phosphorus managements in farmland,e.g.,promote the activation of phosphorus for the paddy soil and control the usage of phosphorus fertilizers for the purple soil.