长期定位施肥对土壤重金属含量的影响

[目的]探讨耕层土壤重金属含量变化,为合理施肥和调控土壤环境提供依据。[方法]在15年长期定位试验研究基础上,分析5种施肥处理(无肥、N、NPK、N+M和N+S)对0～20 cm土层中6种土壤重金属(Cu、Zn、Cd、Cr、Hg和As)的含量变化。[结果]6种元素含量都呈现增加趋势。N+M处理的Zn含量超过土壤环境质量标准2级(pH值6.5～7.5)的限界,Hg含量增加幅度较大,比试验基础值(0.084 mg/kg)增加了114%,比不施肥处理增加了50%。单施N肥(尿素)对土壤重金属影响不大,施用P肥使土壤重金属含量增加。畜禽排泄物为原料的有机肥可使土壤重金属含量提高,特别是Cu、Zn、Hg增加幅度较大。[结论]施肥是影响土壤重金属含量变化的重要因素;对畜禽排泄物为原料的有机堆肥也要合理施用。

Effects of Long- term Located Fertilization on Heavy-metal Content in Soil

[Objective] The objective of the research was to explore the change of heavy-metal content in soil and provide the foundation for rational fertilization and the regulation of soil environment.[Method] Based on long location experiment for 15 years,the change of six heavy metals(Cu,Zn,Cd,Cr,Hg and As) content in 0~20 cm soil treated with 5 different fertilization treatments such as N,NPK,N M(manure),N S(straw) and no fertilizer(CK).[Result] All 6 elements content in soil showed the increasing trend.Zn content in soil applied with N M exceeds the limit of the Soil Environmental Quality Standard II(pH 6.5~7.5).Hg content in soil was increased greatly,being 114% higher than the test foundational value(0.084 mg/kg) and 50% higher than CK.Applying N fertilizer(urea) singly had little effect on the soil heavy-metal,applying P fertilizer increased the heavy metal content in soil.The organic fertilizer which taken the excrements of livestock and poultry as raw materials could increase the heavy metal content in soil,especially increased the contents of Cu,Zn and Hg greatly.[Conclusion] Fertilization is an important factor effecting the change of heavy metal content in soil.The organic fertilizer which takes excrements as raw materials should be used reasonably.