福州市蔬菜地土壤磷淋失的“阈值”研究
Threshold Values on Phosphorous Leaching of Vegetable Soils in Fuzhou
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摘要: 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、CaCl2-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,CaCl2-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 mg·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。Abstract: 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穔g-1 and 205.8 mg穔g-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穔g-1.