Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, PR China.
College of Resources and Environmental Sciences, Hunan Agricultural University, Changsha, PR China.
Glob Chang Biol. 2021 Jun;27(11):2478-2490. doi: 10.1111/gcb.15595. Epub 2021 Mar 23.
Paddy soils make up the largest anthropogenic wetlands on earth, and are characterized by a prominent potential for organic carbon (C) sequestration. By quantifying the plant- and microbial-derived C in soils across four climate zones, we identified that organic C accrual is achieved via contrasting pathways in paddy and upland soils. Paddies are 39%-127% more efficient in soil organic C (SOC) sequestration than their adjacent upland counterparts, with greater differences in warmer than cooler climates. Upland soils are more replenished by microbial-derived C, whereas paddy soils are enriched with a greater proportion of plant-derived C, because of the retarded microbial decomposition under anaerobic conditions induced by the flooding of paddies. Under both land-use types, the maximal contribution of plant residues to SOC is at intermediate mean annual temperature (15-20°C), neutral soil (pH7.3), and low clay/sand ratio. By contrast, high temperature (24°C), low soil pH (~5), and large clay/sand ratio are favorable for strengthening the contribution of microbial necromass. The greater contribution of microbial necromass to SOC in waterlogged paddies in warmer climates is likely due to the fast anabolism from bacteria, whereas fungi are unlikely to be involved as they are aerobic. In the scenario of land-use conversion from paddy to upland, a total of 504 Tg C may be lost as CO from paddy soils (0-15 cm) solely in eastern China, with 90% released from the less protected plant-derived C. Hence, preserving paddy systems and other anthropogenic wetlands and increasing their C storage through sustainable management are critical for maintaining global soil C stock and mitigating climate change.
稻田是地球上最大的人为湿地，具有显著的有机碳（C）固存潜力。通过量化四个气候带稻田土壤中植物和微生物来源的 C，我们发现稻田和旱地土壤中有机 C 的积累是通过不同的途径实现的。与相邻旱地相比，稻田在土壤有机 C（SOC）固存方面的效率要高 39%-127%，在较温暖的气候下差异更大。旱地土壤中微生物来源的 C 补充较多，而稻田土壤中植物来源的 C 比例较高，这是由于稻田淹水导致的厌氧条件下微生物分解的减缓。在这两种土地利用类型下，植物残体对 SOC 的最大贡献出现在中等年平均温度（15-20°C）、中性土壤（pH7.3）和低粘土/砂比条件下。相比之下，高温（24°C）、低土壤 pH（~5）和大的粘土/砂比有利于增强微生物残体的贡献。在较温暖气候下，水淹稻田中微生物残体对 SOC 的更大贡献可能是由于细菌的快速合成代谢，而真菌不太可能参与，因为它们是需氧的。在从稻田转为旱地的土地利用转换情景下，仅中国东部的稻田土壤（0-15cm）就可能因 CO 而损失 504 Tg C，其中 90%来自保护程度较低的植物来源的 C。因此，保护稻田系统和其他人为湿地，并通过可持续管理增加其碳储量，对于维持全球土壤碳储量和减缓气候变化至关重要。
