福州市蔬菜地土壤磷淋失的“阈值”研究

以福州郊区蔬菜地土壤为研究对象,通过室内模拟试验,研究6种不同土壤测试磷(Olsen-P、CaCI2-P、H2O-P、NaOH-P,Bray-P、有机磷)含量与磷素淋失之间的关系,探讨土壤磷素淋失风险评估的指标.结果表明,CaCI2-p、有机磷与淋洗液溶解总磷(DTP)的当次释放量及其累积量具有极显著的相关关系,可作为评价蔬菜地土壤磷淋失风险的指标,以DTP 0.05 nmg·L-1作为引起水体富营养化的临界值,获得本试验区域蔬菜地土壤磷素淋失的CaCl2-P、有机磷阀值分别为14.1 mg·kg-1和205.8 mg·kg-1；以Hesketh2000年提出的“突变点”方法预测土壤磷素淋失风险,得出本试验区域蔬菜地土壤磷发生淋溶的Olsen-P“突变点”为96.6 mg · kg-1·.

Threshold Values on Phosphorous Leaching of Vegetable Soils in Fuzhou

Surface soils of vegetable plots in Fuzhou suburbs were sampled for this study.A simulated continuous leaching test on the soils was conducted to examine the soil-water phosphorus correlation.The results clearly indicated that CaCl2-P and organic P in the soil correlated very significantly to the concentration and accumulation of dissolved P(DTP).Thus,CaCl2-P and organic P were considered excellent indices for the risk evaluation on soil phosphorus leaching.At DTP concentration of 0.05 mg L-1 as the critical value for eutrophication,the CaCl2-P and organic P threshold values for phosphorus leaching in vegetable soils were 14.1 mg·kg-1 and 205.8 mg·kg-1,respectively.According to Hesketh(2000),the "change-point" concentration of the Olsen-P for the vegetable soils was determined to be 96.6 mg·kg-1.