近30年来苏南耕地土壤pH时空变化特征及影响因素分析

Spatial-Temporal Variation and Associated Driving Factors of pH Values in Soils in the Past 30 Years in the Southern Jiangsu Province

苏南地区是我国重要的粮食产区之一,其耕地土壤的酸碱度特征直接影响着土地品质和粮食质量。本文通过调查2010年以来苏南农耕土壤p H空间分布特征,发现苏南土壤p H呈现西酸东碱格局,这与自然条件和人为改造行为密切相关。近30年来苏南土壤p H时空变化在2003年前后呈现两种模式:总体上,1980年至2003年期间,土壤发生酸化和碱化的地区与1980年至2010年来的总变化特征基本一致,而2003年至2010年近10年来部分地区土壤酸碱变化趋势出现逆转,以镇江句容地区的先碱化后酸化和苏州无锡地区的先酸化后碱化最为典型。本文分析认为,地区间土地利用格局和利用方式的时空差异所导致的缓冲物质的增减更替,是造成苏南土壤p H时空变化区域差异的主要驱动力。

The Southern Jiangsu Province is one of the major Chinese grain-producing areas, where the quality of cultivated soil andfarm produce are significantly affected by the changes of soil pH values. Through the investigation of pH values of cultivated soils in theSouthern Jiangsu Province in 2010s, and comparing with two spatial distribution maps of soil pH in 1980 and 2003 from previousstudies, the spatial-temporal variation of pH values and associated factors have been discussed in this paper. The results showed thatthe spatial distribution pattern of soil pH in 2010s was significantly different from that in 1980, with lower soil pH values in the west partof the study areas than those in the east in 2010s, which is associated with natural conditions and social behaviors. Two phases of pHchange have been observed in the context of complex changes in soil chemical properties during the past 30 years. The variation trendsof pH values in different regions from 1980 to 2003 were similar to the major trends from 1980 to 2010s, while transformations haveemerged in the last decade since 2003, especially presented in Jurong city where soil acidification has occurred in the later 10 yearsafter alkalization in previous 20 years, and Suzhou-Wuxi Countries where it displayed the opposite trend. The decrease of pH values insoils can be explained by both heavy application of chemical fertilizers and industrial acid deposition. In addition, urbanization andcement production also played an important role in the pH increase. It is concluded that the different variations of pH values are causedby the waxing and wining of buffer substances in soil, which are mainly forced by the changes in land utilization in different regions.