水田长期改种蔬菜土壤化学性状变化特征

Vegetable Crop Plantation Induced Changes in Chemical Characteristics of Paddy Soils

为了解水田长期改种蔬菜后土质量的变化,从浙西北采集了32对水田及其长期改种蔬菜的旱地对比表层土壤样品,分析了土壤p H、水溶性盐分、有机碳、全氮、全磷、有效磷、速效钾、有效铁、有效锰和6种重金属元素含量,探讨了水田长期改种蔬菜后土壤化学性状的变化特征。结果表明,水田改为蔬菜地后,土壤水溶性盐分呈增加趋势,有机碳呈下降趋势,全磷、有效磷和速效钾明显增加;土壤趋向酸化,p H下降;土壤有效铁和有效锰呈现下降趋势,而土壤Cd、Cu、Pb、Hg和Zn的积累较为明显。p H变化量与对照水田p H呈"U"字型关系,近中性土壤的p H下降量最大,向酸性和向碱性两侧的p H变化量逐渐减小。有机质和全氮的下降量随对照水田土壤有机质和全氮含量增加而增加,两者呈显著的正相关。水田长期改种蔬菜后土壤酸化、盐渍化明显,有机碳呈下降趋势;土壤环境质量也有所下降。

In order to study the change of soil quality of land use alteration from paddy field to vegetable garden, the author collected 32 pairs of surface soil samples from paddy field and vegetable garden altered from paddy field in the northwestern Zhejiang, analyzed the change of soil chemical characteristics by measuring pH, water soluble salt, organic carbon, total nitrogen, total phosphorus, available phosphorus, available potassium, available Fe, available Mn and 6 kinds of heavy metal elements. The results showed that, after altering into vegetable garden, the content of soil water total phosphorus, available phosphorus and available soluble salt increased while organic carbon declined, potassium increased obviously. Meanwhile, the soil tended to be.acidification, pH decreased. The contents of soil available Fe and Mn decreased, while Cd, Cu, Pb, Hg and Zn accumulated significantly. There was a U-form relationship of pH between the altered and original soil, pH of neutral soil decreased significantly, but slightly for acidic and alkaline soils. The decreased amount of organic carbon and total N rose with the increase of the content of organic matter and total N in CK, there was a significant positive correlation between them. After altering to vegetable garden, soil acidification and salinization were obvious, soil organic carbon decreased and soil environmental quality also declined with the transformation.