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菌渣还田可改善土壤结构和供给作物生长所需部分养分,然而其所残留的重金属镉(Cd)和铅(Pb)可能污染土壤.为了解其施用量和环境容量之间的关系,在观察空白对照(CK)、常规施肥(T1)、单施菌渣提供100%氮(T2)、高量单施菌渣提供125%氮(T3)、菌渣和化肥配施各提供50%氮(T4)、菌渣和化肥配施分别提供75%和25%氮(T5)处理下土壤耕作层(0~(-2)0 cm)Cd和Pb含量变化的基础上,采用地累积指数法及污染指数法进行污染评价,应用静态容量法估算其环境容量.结果表明,土壤Cd和Pb含量随着菌渣施用量的增加及麦稻轮作周期延伸呈上升趋势,且水稻季土壤Cd和Pb含量上升趋势较小麦季略有减缓.污染评价结果表明,一年轮作周期后各处理下土壤Cd和Pb地累积指数(-0.51-0.29)和单因子污染指数(0.50-0.61)及综合污染指数(0.55-0.59)均属无污染等级,其中T4处理对土壤污染最低.经测算,土壤Cd和Pb静态环境容量为26.88 kg hm~(-2)和85.08 kg hm~(-2),菌渣适宜年还田量为8 183~(-1)2 681 kg hm~(-2)a~(-1),可安全使用15年.综上,重金属含量不超标的菌渣具备替代化肥的潜力,适量施用能够延长土壤的安全使用年限.
Residues can improve the soil structure and supply some of the nutrients needed for crop growth, however, residual cadmium (Cd) and lead (Pb) may contaminate the soil. To understand the relationship between application rates and environmental capacity, CK, conventional fertilization (T1), 100% nitrogen (T2) with single application of bacteria residue and 125% nitrogen (T3) with single application of bacteria residue, and 50% of nitrogen (T4). The changes of Cd and Pb contents in soil tillage layer (0 ~ (-2) 0 cm) under 75% and 25% nitrogen (T5) treatment were respectively provided by microbial community and chemical fertilizers. And pollution index method, the environmental capacity was estimated by static capacity method.The results showed that the content of Cd and Pb in soil increased with the increase of the amount of bacteria residue and the cycle extension of wheat rotation, and the contents of Cd and Pb The trend of soil moisture content was slightly slower than that of wheat.The pollution evaluation results showed that the accumulation index of soil Cd and Pb (-0.51-0.29) and single factor pollution index (0.50-0.61) and the comprehensive pollution index (0.55-0.59) were non-polluting grade, among them, T4 treatment had the lowest soil pollution.According to the calculation, the soil Cd and Pb static ring The soil available capacity was 26.88 kg hm ~ (-2) and 85.08 kg hm ~ (-2), respectively, and the suitable annual amount of residue was 8 183 ~ (-1) 2 681 kg hm ~ (-2) a ~ ), Can be safely used for 15 years.In summary, not exceeding the heavy metal content of bacteria residue with the potential of alternative fertilizers, the amount of application can extend the safe life of the soil.