华北地区有机种植与常规种植土壤质量比较研究

为探讨有机种植与常规种植两种不同种植方式对土壤质量的影响,本文在华北地区选取典型的有机种植基地与附近相似条件的常规种植地块,比较了不同种植方式下土壤体积质量、土壤中水稳性团聚体及土壤中各养分含量和土壤中7种重金属含量。结果表明:相比常规种植,有机种植降低了土壤体积质量,提高土壤中水稳性大团聚体数量,提高了土壤中水稳性团聚体的MWD值和GMD值,降低了分形维数D,提升了土壤水稳性团聚体稳定性,提高了土壤抗侵蚀的能力。有机种植方式下土壤中有机质含量相比常规种植提高了20%~80%,土壤中速效磷、速效钾、碱解氮和全氮、全磷等养分含量也显著提高,说明有机种植有利于土壤培肥,提高土壤肥力。与土壤背景值相比,土壤中重金属含量有不同程度的增加和积累,曹县有机基地As含量超过土壤环境质量国家一级标准,肃宁有机基地土壤中Cu、Zn含量接近国家一级标准。在调查地区,有机种植降低了土壤中Cr、Cd、Hg污染的威胁,但由于施入有机肥的质量差异,存在重金属Cu、Zn、As富集的风险。相比常规种植,有机种植有利于改善土壤结构,提高土壤综合肥力,土壤中重金属污染的风险主要与施入的有机肥质量有关,有机种植应加强对有机肥源的监控,合理施肥。

Effect of Conventional and Organic Farming on Soil Quality in Regions of Northern China

In order to study the effects of conventional and organic cropping systems on soil quality , experiment was conducted by choosing topical organic and conventional farms,for studying soil bulk density and water stable aggregates and soil nutrient and the concentrations of soil heavy metals under different cropping systems.The results show that compared with the conventional farming, organic farming reduce soil bulk density, improve the soil moisture and the value of MWD and GMD of soil aggregate , reduce soil aggregate fractal dimension D, indicate that organic cultivation can effectively reduce the soil compactness,improve the quantity and stability of water stable soil aggregate..Organic farming improve the content of soil organic matte,and the content of nitrogen,phosphorus,potassium significantly,so organic farming is beneficial to improve soil fertility. The concentration of heavy metal in soil including Cu, Zn, Pb, Cr, Cd, Hg, As in organic farms do not exceed the national first standard , organic cultivation reduce the threat of Cr, As, Hg, Cd contamination in soil,but there is risks of Pb, Cu, Zn,enrichment because of the different quality of organic mature.Conclusions:Compared with conventional farming,organic farming will be helpful to improve soil structure , raise soil fertility , reduce the overall risk of soil heavy metal contamination.