近50年浙江省耕作土壤有机质和酸碱度的变化特征

Changing Characteristics of Organic Matter and pH of Cultivated Soils in Zhejiang Province over the Last 50 Years

为了解浙江省耕作土壤有机质和酸碱度的长期演变，利用历史资料和近期土壤质量调查数据探讨了近50年来浙江省耕作土壤有机质和酸碱度的变化特点．结果表明，近50年来，浙江省耕作土壤有机质和土壤酸碱度发生了较大的变化，但其变化程度和方向因历史时期和土壤类型而异．从1958—1980年，水稻土有机质积累明显，平均增加幅度达40．34％；土壤pH值有轻微的增高趋势，平均上升约0．05个pH值单位．从20世纪80年代初至2008年，水稻土有机质含量总体平均降幅为5．58％，但各土壤分布区中水稻土有机质的变化有所差异，其中，河谷平原区呈现增加趋势，而水网平原、丘陵山地和滨海平原区呈现下降趋势；潮土有机质含量平均增幅为29．48％；盐土有机质含量平均增幅为14．60％；土壤pH值普遍呈现下降，全省耕作土壤平均下降了0．25个pH值单位，水稻土pH值的平均下降高于盐土和潮土．分析认为，施肥结构和土地利用方式的变化是引起耕作土壤有机质和酸碱度变化的主要原因．

By comparing the current quality investigation data of cultivated soils in Zhejiang province with the past data, changing characteristics of organic matter and pH value of the soils in this province over last 50 years were analyzed. The results showed that content of organic matter and pH value of the cultivated soils changed greatly during past 50 years, and the changes varied with historical periods and soil types. From 1958 to 1980s, accumulation of soil organic matter was obvious, soil organic matter increased averagely by 40.34% , and the mean pH increased slightly by 0. 05 of pH unit. From 1980s to 2008, the mean content of organic matter in paddy soils decreased by 5.58%. The changes of soil organic matter varied with distribution zones of the paddy soils. The mean content of organic matter of paddy soils in valley plain increased with time, and those in plain with water network, hilly area and coastal plain decreased with time. The mean contents of organic matter in fluvio-aquic soil and coastal saline soil in the year 2008 were 29.48% and 14.60% respectively higher than those in 1980s. As compared with those obtained at 1980s, the cultivated soil in this province have been significantly acidified in the past thirty years, the mean pH value declined by 0. 25 of pH unit, and the decline of pH value of paddy soils was greater than those of fluvio-aquic soil and saline soil. Changes in fertilization structure and conversion of paddy fields to upland were thought as main causes of the changes in both soil organic matter and pH value.