Abstract:
The spatiotemporal changes of soil pH are of great significance in assessing the evolution of regional soil quality and function. The significant decline of soil pH during 1980 s—2010s in China has been reported by many papers, showing the overuse of chemical fertilizer was one of the important driving factors. To weaken the adverse effect of chemical fertilizer, straw returning to soil and formula fertilization started to be extensively implemented since 2005, which was an important change in soil management across the national scale. But the effects of them on soil pH changes had rarely been evaluated. In this paper, the changes of soil pH in a typical agricultural region of North China during the periods of 1984—2007 and 2007—2017 were investigated by means of sequential gaussian simulation based on 1287 soil samples. The results showed that soil acidification had taken placed in the most of fluvo-aquic soil, non-loess derived cinnamon soil and Shajiang black soil during the period of 1984—2007. During the period of 2007—2017, the acidification of fluvo-aquic soil showed a trend of recovering because of straw returning and formula fertilization, no significant changes were in non-loess derived cinnamon soil, but a further decrease was in Shajiang black soil. The area dominated by loess-derived cinnamon soils showed an increase in soil pH in the both periods. It was found that the different effects of returning straw to the field and formula fertilization on easing soil acidification in different soil types could partly be attributed to their differences in texture and initial pH values. The soil pH increased in the loess area was related to the erosion of surface soil and the subsurface soil with higher pH value. In order to achieve better soil pH adjustment in North of China, in addition to insisting on the straw returning to soil and formula fertilization, more localized and optimized management strategies should be developed with considering the effects of soil category, soil texture, soil parent material and landform.