蔬菜种植年限对土壤磷素吸附解吸特性的影响

为揭示不同种植年限土壤磷的固定和释放机制,通过土壤磷的等温吸附、解吸试验研究种植年限分别为3～5年、15～20年、25～30年的黄棕壤0～5cm和5～20cm土层磷的吸附、解吸特性。结果表明:土壤磷的等温吸附曲线、吸附量-解吸量曲线分别与Langmuir方程(R2为0.8728～0.8436)、二次函数方程拟合良好(R2为0.9545～0.9970);随蔬菜种植年限延长,表层土壤磷最大吸附量(Qm)、磷最大缓冲容量(MBC)明显降低,而土壤磷吸附饱和度(DPS)和解吸率明显提高;种植年限15～20年、25～30年土壤磷的解吸率明显高于3～5年土壤。对表征土壤磷素吸附、解吸特性的主要因子如MBC及DPS等作相关分析发现,无定形铁铝含量的变化是影响土壤磷吸附解吸特性的主要因素。

Effect of the number of years of vegetable cultivation on soil phosphorus sorption-desorption characteristics

An experiment involving 3~5, 15~20 and 25~30 years continuous vegetable cultivation was carried out to determine fixation and release mechanisms of soil phosphorus in cultivated yellow brown soils. Based on the results, phosphorus isothermal adsorption and adsorption-desorption curves are respectively described by Langmuir equation and quadratic equation. With increasing years of cultivation, the maximum phosphorus adsorption (Q_m) and maximum buffer capacity (MBC) of surface soil decrease significantly. However, degree of phosphorus saturation (DPS) and phosphorus desorption rate increase. Phosphorus desorption rates in 15~20- and 25~30-year cultivated vegetable soils are significantly higher than that in the 3~5-year cultivated vegetable soils. Correlation analysis for the main factors affecting soil phosphorous adsorption-desorption (e.g., MBC, DPS, etc.) reveals that soil amorphous Fe-Al content significantly affects soil phosphorus adsorption-desorption.