Climate warming and agronomic practice interactively alter soil carbon stock in dry farmland in China

Abstract Understanding drivers of soil organic carbon (SOC) dynamics and stocks is critical for carbon (C) neutrality in Earth’s extensive dryland croplands. Here, we analyzed 721 soil samples across northern China and revealed divergent regional dynamics of SOC stocks in topsoil (0–20 cm) over three decades. Agricultural intensification in northern China, marked by tripled productivity via strategic N-fertilization and policy-driven increases in straw return, created a major C sink (+3.1 Mg C ha −1 ), offsetting ~1.5% of China’s average annual emissions. Conversely, Northeast China experienced SOC depletion (−3.9 Mg C ha −1 ; ~12% loss since 1980s) driven by warming-enhanced decomposition of organic matter. Encouragingly, an annual straw return in excess of 270 kg C ha −1 could offset SOC losses in the face of future warming. Therefore, it is imperative to implement effective soil management practices and adaptation strategies to bolster soil resilience and health, as continued climate warming may undermine soil carbon sequestration.