集约化蔬菜地土壤磷素累积特征及流失风险

Accumulation and Leaching Risk of Phosphorus in Vegetable Soils Under Intensive Cultivation

  • 摘要: 以南京市郊集约化蔬菜长期种植基地为对象,采集蔬菜种植年限分别为3~5、15~20、25~30 a的土壤,测定土壤全磷( TP) 、速效磷(Olsen-P) 、水溶性磷(CaCl2-P) 、生物有效磷(NaOH-P)的含量,并对0—20 cm土层磷素吸附特性进行分析,通过研究土壤磷吸附饱和度(DPS) 、最大缓冲容量(MBC)来对土壤磷素流失风险进行评估。结果表明,在0—20 cm土层,除NaOH2P外,其余各形态磷( TP、Olsen-P、CaCl2-P)都随种植年限延长呈增加趋势。不同种植年限土壤TP、Olsen-P、CaCl2-P、NaOH-P主要积累在0—20 cm土层,且随着土层深度的增加土壤磷的累积量逐渐降低。DPS随种植年限延长而升高,种植年限25~30 a的菜地0—5 cm土层DPS超过土壤磷素流失环境敏感指标临界值(25% ) ,其MBC也最低,表明随着蔬菜种植年限的延长土壤磷素流失风险加剧,且流失风险主要体现在0—5 cm土层。

     

    Abstract: In order to study accumulation and leaching risk of soil phosphorus, soil sampleswere collected from vegetable fields, different in intensive vegetable cultivation history (3 - 5, 15 - 20 and 25 - 30 years) in the suburbs ofNanjing for assay of concentrations of total phosphorus ( TP) , available phosphorus (Olsen-P) , dissolved reactive phosphorus (CaCl2-P) and bio2available phosphorus (NaOH-P) , and Padsorption in 0 - 20 cm soil layer, and for assessment of soil phosphate leaching risk through determination of degree of phosphorus saturation (DPS) and maximum buffer capacity (MBC)of the soils. Results show that the longer the history of intensive vegetable cultivation, the higher the accumulation of phosphorus for all Pfractions, except forNaOH-P, which was higher in soils of 3 - 5 a than in the other two groups. TP, Olsen-P, CaCl2-P and NaOH-P accumulatedmainly in the 0 - 20 cm soil layer, and decreased in concentration with the dep thin profile. DPS increased with the history. In the 0 - 5 cm soil layers of soils of 25 - 30 a, the concentration of DPS was even higher than 25% , the environmental sensitive index for soil P loss, while MBC was the lowest, suggesting that the leaching risk of soil phosphorus riseswith the cultivation history, particularly in 0 - 5 cm soil layer.

     

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