Spatiotemporal variation of soil PH in the past 30 years of Guangdong Province, China

Based on the 1980s´ soil inventory data and the 2002-2007 soil pH data of Guangdong Province, the spatiotemporal variation of soil pH in the Province in past 30 years was studied. In the study period, the spatial distribution pattern of soil pH had less change (mainly acidic), except that in Pearl River Delta and parts of Qingyuan and Shaoguan (weak alkaline). The overall variation of soil pH was represented as acidification, with the average pH value changed from 5.70 to 5.44. Among the soil types, alluvial soil had an increased pH, lateritic red soil, paddy soil, and red soil had a large decrease of pH, lime soil was most obvious in the decrease of pH and its area percentage. The soil acidification was mainly effected by soil characteristics, some natural factors such as acid rain, and human factors such as unreasonable fertilization and urbanization.