不同利用方式土壤中磷的吸附与解吸特性

研究不同利用方式土壤对磷的吸附解吸特性及其影响因素。采用室内恒温培养法研究了湖南典型土壤(红壤、潮土和紫色土)的不同利用方式(旱地、水田)土壤对P的吸附和解吸过程。土壤对磷的吸附解吸过程是分阶段进行的,用Langmuir方程拟合程度比Freundlich方程高,相关系数均在0.90(P<0.05)以上;从最大吸附量(Qm)、吸附反应常数(K)和最大缓冲容量(MBC)3项吸附参数综合考虑,旱地对P的吸附无论在强度还是容量方面均大于同母质的水田土壤;解吸率随着吸附量的增加而增大,其大小为旱地<水田。Qm与<0.002 mm粘粒及无定形铁含量呈正相关,相关系数分别为0.95和0.94(P<0.05)。不同利用方式土壤P吸附解吸特性差别较大,针对不同土壤应采取不同的磷素管理措施以实现作物增产和保护环境的双重效益。

Characteristics of phosphate adsorption and desorption in soils under different utilization

The characteristics and influencing factors of phosphate adsorption and desorption in soils under different land uses (dryland and paddy field) were investigated in this study. Through the constant-temperature incubation experiment, the process of phosphate adsorption and desorption, which carried out by stages, was studied in three various soil types (red soil, alluvial soil and purple soil) of Hunan respectively. The results showed that Langmuir equation gave a better fitting capability than Freundlich equation, all of correlation coefficients of Langmuir equation were beyond 0.90(P<0.05). By comprehensively taking Q_m (maximum quantity of adsorption), K (adsorption constant) and MBC (maximum buffing capacity) into account, we found in the aspects of both intensity and capacity of P adsorption that dryland soils showed superior to paddy soils. The phosphorus desorption rate increasing with the level of adsorbed P in dryland was greater than that in paddy soil. Qm had positive correlation with the content of clay (<0.002 mm) and amorphous iron with correlation coefficient of 0.95 and 0.94, respectively(P<0.05). The characteristics of phosphate adsorption and desorption varied greatly. Therefore, different phosphorus management measures should be adopted in view of the different soils in order to achieve higher crop production and environmental benefit.