Stabilization of acidification in China’s cropland soils

Abstract

China’s cropland soil has faced acidification since the latter half of the twentieth century; however, the temporal and spatial variations of this are poorly known. Here we analyse cropland soil acidification using 7,024 regional surveys and a machine learning model to project spatiotemporal variations in cropland topsoil pH across China from 1985 to 2040. Our results reveal a turning point in China’s agricultural soil chemistry: consistent acidification from the 1980s ceased as a whole around 2013 (with a cumulative pH decline of ~0.25 units during 1985–2013), correlating strongly with changes in nitrogen fertilizer application patterns consequent to agricultural policy reforms. Regional heterogeneity was observed, with paddy fields exhibiting pH recovery post-2013 while values in dryland soils remained largely static since 2000. These findings underscore the critical role of agricultural policy and nitrogen fertilizer management in shaping soil health dynamics. This Article offers guidance for sustainable agriculture in China while providing insights applicable to global farming practices. China’s cropland soil experienced acidification between the 1980s and about 2013 correlating with nitrogen fertilizer application patterns, followed by heterogeneous soil pH recovery, according to combined regional surveys and machine learning.