Changes in cropland soil inorganic carbon and its relationship with nitrogen fertilization and precipitation over the past 40 years in the Sichuan Basin, China

作者：Aiwen Li, Jinli Cheng, Dan Chen, Xinyi Chen, Yaruo Mao, Qian Deng, Bin Zhao, Wenjiao Shi, Zemeng Fan, John P. Wilson, Tianfei Dai, Guirui Yu, Qiquan Li · 发表于：Journal of Integrative Agriculture · 年份：2025 · DOI：10.1016/j.jia.2025.04.039 · 被引用次数：2 · 研究领域：Soil Carbon and Nitrogen Dynamics、Plant Ecology and Soil Science、Forest, Soil, and Plant Ecology in China

• Machine learning models were developed to fill the missing SIC of soil samples. • Cropland soils experienced an overall decrease in SIC during the 1980s–2010s. • Precipitation was the dominant driver and controlled the effect of N fertilization. • The magnitude of SIC decline varied parabolically with N fertilizer rates. • The high N fertilizer rate did not cause SIC loss in areas with rainfall<950 mm. Widespread soil acidification driven by nitrogen (N) fertilization and precipitation challenges the conventional notion of the long-term stability of soil inorganic carbon (SIC) in agroecosystems. However, the changes in SIC with precipitation and N fertilization remain ambiguous. Based on 4,000+ soil samples collected in the 1980s and 2010s and by developing machine learning models to fill the missing SIC of soil samples, this study generated 3,697 paired soil samples between the two periods and then investigated the cropland SIC change and explored its relationship with precipitation and N fertilization across the Sichuan Basin, China. The results showed an overall SIC loss, with a decline of the mean SIC by 15.73%. SIC change varied with initial soil pH and initial SIC and exhibited an exponential relationship with soil pH change, indicating the changing role of carbonates in providing acid-buffering capacity. There was a parabolical relationship between the magnitude of SIC decline and N fertilizer rates, and low N fertilizer rates contributed to a reduction in SIC loss, ...