Spatial heterogeneity of soil acidification driven by cropping patterns and soil types in red soil dryland of Southern China

The red soil dryland in southern China has the largest area of acidic soils countrywide. We calculated acid production based on the principle of charge balance and the annual output and input of major elements to evaluate soil acidification rate under different nutrient input-output budgets (crop cultivation and land abandonment) in red soil dryland of the Jitai basin in Jiangxi Province. Semi-variance analysis revealed moderate spatial autocorrelation in soil acidification rate, with a nugget effect of 49.97 %. Structural and random factors accounted for comparable proportions of spatial variation in soil acidification rate, indicating the impacts of artificially controlled nutrient budgets and inherent soil properties. Under agricultural management, soil acidification rate reached its highest level in sesame plots (7.50 keq·ha⁻¹·yr⁻¹), with the lowest rate in rapeseed plots (2.46 keq·ha⁻¹·yr⁻¹). Abandoned plots experienced slow soil acidification (0.96 keq·ha⁻¹·yr⁻¹). Chemical fertilizer application contributed the greatest to soil acidification rate in rapeseed plots (58.39 %), and crop removal contributed prominently in other cultivated plots (sesame: 44.66 %, peanut: 138.70 %, sweet potato: 75.25 %). Organic fertilizer application was a negative contributor, alleviating soil acidification in all cultivated plots. Soil acidification rate differed significantly with soil type and parent material. A range of soil physicochemical properties exhibited linear and nonlinear effects on soil acidification rate. This study underscores the role of both nutrient budgets and soil properties in driving soil acidification in red soil dryland. Effective control of red soil acidification necessitates dryland managers to focus on nutrient input-output and soil quality improvement, especially optimizing the type of nitrogen fertilize and avoiding excessive removal of crop straw.