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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NaOH-P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。
Taking the intensive vegetable long-term planting base in suburb of Nanjing as the object, the soil with vegetable planting years of 3-5, 15-20, 25-30 a were collected. The contents of TP, Olsen-P, Phosphorus (CaCl2-P) and bio-available phosphorus (P-P) in soil were analyzed. The characteristics of phosphorus adsorption in 0-20 cm soil layer were analyzed. The effects of soil phosphorus adsorption saturation (DPS), maximum buffering capacity ) To assess the risk of soil phosphorus loss. The results showed that all the forms of phosphorus (TP, Olsen-P and CaCl2-P) increased with the extension of planting age except NaOH-P in 0-20 cm soil layer. Soil TP, Olsen-P, CaCl2-P and NaOH-P accumulate mainly in 0-20 cm soil layer in different planting years, and the accumulation amount of soil phosphorus decreases with soil depth increasing. DPS increased with the extension of planting years. DPS of 0-5 cm soil layer in 25-30 years of planting years exceeded the critical value (25%) of sensitive index of soil phosphorus loss and the MBC was the lowest, indicating that with the planting of vegetables The extension of the risk of soil phosphorus exacerbated, and the risk of loss is mainly reflected in the 0-5 cm soil layer.