Spatio-temporal changes of cropland soil pH in a rapidly industrializing region in the Yangtze River Delta of China, 1980-2015

The impacts of rapid industrialization on spatio-temporal changes in soil pH have drawn major attention from the scientific community and decision-makers. A total of 1185 topsoil samples (0-20 cm) were collected from southern Jiangsu Province of China in 1980, 2000, and 2015, and the geostatistical sequential Gaussian simulation (SGS) was used to quantify the spatio-temporal patterns of changes in soil pH and identify the areas with significantly-declined pH. A significant topsoil acidification occurred in major croplands of the study area, with mean decrements of 0.56 and 0.52 units over the periods of 1980-2000 and 2000-2015, respectively. A significant decrease in pH occurred in the areas surrounding Taihu Lake during 1980-2000, and a further decrease was evident predominantly in the northeast during 2000-2015. Over the entire 35-year period, the soil pH for approximately 79% of the study area declined significantly. The decline over the first two decades (1980-2000) was largely attributed to increased chemical fertilizer inputs and the development of industries, while the further enhanced industrial emissions resulting from the significant expansion of factories were the primary reason for the accelerated soil acidification in the subsequent 15 years (2000-2015). Results from this study may serve as a basis for developing management strategies to achieve better soil quality in similar areas moving toward industrialization.