Organic carbon loss from the black soil region threatens food security in China

Changes in soil organic carbon (SOC) within the world's most fertile black soils pose a major challenge to soil carbon-based climate change mitigation and food security. Yet limited understanding of the spatiotemporal dynamics of SOC across different depths in black soils and their effects on crop yields has constrained sustainable soil management (SSM). Using 18,314 field observations from China's black soil region, we integrated process-based and machine learning approaches to reconstruct and project spatiotemporally consistent SOC time series at the centennial scale. Results show that cropland topsoil (0–30 cm) SOC concentrations decreased from 24.2 to 20.2 g kg−1 between 1980 and 2023, with minimal changes in deeper soils. Under future climate scenarios, topsoil SOC may decline by 22%–29% by 2100, potentially reducing crop yields by 263–412 kg ha−1, which corresponds to 5.7%–8.9% of total crop production in Northeast China in 2023. Promoting SSM through digital agriculture could help mitigate declines in SOC and crop yields in China, while global coordination is urgently needed to establish standardized SOC monitoring systems and safeguard the sustainable productivity of black soils worldwide.