华东典型地区有机与常规农业土壤重金属含量的比较研究

A Comparison of Heavy Metals Concentration in Soils of Organic and Conventional Farming in Typical Regions of Eastern China

以上海市奉贤县星辉园艺场有机大葱、白花菜基地,江苏省溧水县共和有机水稻基地和安徽省岳西县余畈有机猕猴桃基地为研究对象,通过采样监测,比较研究了有机农业与周围相应常规农业土壤Cu、Zn、Pb、Cd、Cr和Ni等6种重金属含量的差异性。结果表明,整体上有机农业土壤重金属污染的威胁较小,但如缺乏对有机肥原料的监控,施用Cu、Zn和Cr含量较高的原料制作的有机肥,往往造成土壤中Cu、Zn和Cr的富集,进而会威胁有机食品的品质与安全。

To assess the effect of organic farming on soil heavy metals, concentrations of heavy metals including Cu, Zn, Pb, Cd, Cr and Ni were detected for the soils under the practices of organic and conventional farming. Three sites in eastern China where organic farming has been performed are involved, includingorganic spring onion and cauliflower in Xinghui of Fengxian County,Shanghai City, organic rice farms in Lishui County of Jiangsu Province, and organic kiwifruit orchards in Yuexi County of Anhui Province. The results indicate that concentrations of the six heavy metals in soils accord with the first class standard of Environmental Quality Criterion in Soil (GB15618—1995) for the three sites. Compared with the conventional farming, the concentrations of Pb, Cd and Ni decreased remarkably, while that of Cu increased obviously in the organic farming soils. The concentrations of Cr and Zn in the organic farming soils are a little higher than that in the conventional farming in the plots of Fengxian and Lishui counties. The increase of Cu, Cr and Zn might attribute to the application of chicken and pig manure for some heavy metals are feedstuff additives. By contrast,the concentrations of Cr and Zn are lower in the organic kiwifruit orchards in Yuexi County where green manure is usually amended as organic fertilizer. These suggest that the quality of organic fertilizers should be carefully controlled to promote the development of organic agriculture in China.