红壤丘陵区农田土壤酸化的时空变化研究

Spatio-temporal variation of soil acidification in hilly red soil croplands

通过GPS技术,采集38个农田土壤样品,研究了红壤丘陵区农田土壤pH的时空间变化特征。结果表明:20年来,江西省兴国县农田土壤pH平均下降0.94个单位。pH下降的面积为645.9 km2,降幅在1.0～2.0个单位,主要分布在千枚岩、花岗岩和红砂岩发育的土壤地区,面积分别为296.1 km2、136.2 km2和42.2km2;pH增加的面积有24.1 km2,主要分布在紫色页岩发育的土壤地区,面积为11.3 km2。从土壤类型看,pH值下降的土壤主要为潴育型水稻土;从海拔上看,pH增加的土壤主要分布在海拔300 m以下的地区,pH降幅最大的土壤主要分布在海拔300 m以下及300～500 m的地区。相关分析显示土壤pH变化量与初始pH呈负相关关系,与海拔、有机质含量、黏粒含量呈正相关关系,通过线性回归模型可以预测pH的变化量。

Using Geographical Information System（GIS） and data from 58 sampling sites in hilly red soil croplands, the spatial and temporal distribution characteristics of pH were investigated. The results indicate that average soil pH decreases by 0.94 and pH decreasing area is 645.9 km^2 in 20 years, pH decreases in the range of 1.0 - 2.0, and is mainly distributed in soils derived from phyllites, granites and red sandstones, with approximately areas of 296.1 km^2, 136.2 km^2 and 42.2 km^2 respectively, pH increasing soil area is 24.1 km^2, and is largely distributed in soils derived from purple shale, which area is approximate 11.3 km^2. Based on soil type, areas with decreasing pH are the water loggogenic paddy soils; elevation wise, areas with increasing pH are below 300 m, though areas with the highest decrease in soil pH generally lies below 300 m or between 500 m and 300 m. Correlation analysis shows that change in pH is negatively correlated with initial pH and positively correlated with elevation, organic matter and clay content. Change in pH in these regions can be predicted based on multi-linear regression models.