广州城郊菜地土壤磷素特征及流失风险分析

通过化学分析和土壤淋洗试验对广州城郊菜地土壤磷素特征和流失风险进行了研究和分析。结果表明.广州城郊菜地土壤全磷含量极高;与自然土壤相比较,菜园土壤无机磷比例增大、有机磷比例降低;无机磷中的AI-P、Fe-P比例增加.O-P比例降低,Ca-P比例基本一致;土壤Olsen P、Bray-1 P、Mehlich-1 P、0.01mol/L CaCl_2和H_2O提取的磷含量相当高;土壤淋洗液中溶解态磷和总磷持续保持很高的浓度,土壤磷供应强度大。菜园土壤中磷进入水体引起水体磷浓度增加,导致水体富营养化风险大;土壤磷的测定值可作为土壤磷流失风险和对水环境影响程度的评估依据。菜地应作为农业非点源磷污染的优先控制区、应通过严格控制磷肥的投入和合理施肥等控制磷的流失。

Phosphorus characteristics and loss risk assessment of vegetable garden soils in the suburbs of Guangzhou city

The phosphorus characteristics and loss risk assessment of vegetable garden soils in the suburbs of Guangzhou city were studied by chemical analyses and leaching experiment. The results indicated that total P content of vegetable garden soils was very high; The proportion of inorganic P was higher and organic p lower, Al-P, Fe-P were higher, O-P was lower and Ca-P was similar compared with natural soil in the same region. The content of Olsen P, Bray-1 P, Mehlich-lP and extractable P with 0.01 mol/L CaCl2 and H2O were very high and exceeded crop needs. The dissolve and total P concentrations in leachate were high and soil had high P supply intensity. The possibility of P in vegetable garden soils loss to water and leading to eutrophication risk was high. The soil test P could be provided basis for soil P loss risk and effect degree on water environment. Vegetable garden should be regarded as the first controlled district for agricultural nonpoint source P pollution, strictly P fertilizer input and rational application of fertilizer should be taken to decrease soil P loss.