Researchers from the Institute of Subtropical Agriculture, Chinese Academy of Sciences, in partnership with international colleagues, made strides in reveal soil organic carbon sequestration mechanisms in Eastern China. They sampled 20 pairs adjacent paddy and upland soils from mid-temperate to tropic zones in eastern China, and separated bulk soils into aggregate and free mineral fractions via density fractionation to determine the contributions of aggregate protection and mineral association to SOC sequestration. Then,  microbial necromass and metabolism in these fractions were measured to determine the contribution of microbial participation in SOC sequestration. The study was published in Agriculture, Ecosystems & Environment on July 30th,The sequestration of soil organic carbon (SOC) in agricultural lands is pivotal in mitigating greenhouse gas emission and elevating soil fertility. Eastern China is scattered distributed with extensive agricultural lands in mid-temperate, warm temperate, subtropic and tropic zones from north to south. These lands are diverse in climatic and edaphic conditions. .In their most recent study, the proportion of SOC in aggregate fractions was decreased from mid-temperate to tropic zones, while that in free mineral fractions was increased. The pearson correlation analysis showed that the enriched exchangeable calcium and magnesium as well as glomalin-related soil proteins in northern climates strengthened aggregate protection, while enriched sodium dithionite extracted iron and aluminum oxides in southern climates intensified mineral association. As for microbial participation, the contribution of microbial necromass C to free mineral-associated C formation increased from mid-temperate to tropic zones. This was attributed to more extensive microbial anabolism in southern regions characterized by wetter and warmer climate condition.

This research indicated that SOC sequestration in northern climates was prevailed by aggregate protection, while in southern climates was characterized by mineral association and microbial participation. “These findings reveal the contrasting mechanisms of SOC sequestration in agricultural lands from mid-temperate to tropic zones in eastern China ”Said Prof. Xiangbi Chen, the corresponding author of the study,“and provide scientific basis for pertinent strategies to manage soil C stocks in agricultural ecosystems.”

Contact:Xiangbi Chen

E-mail: xbchen@isa.ac.cn

Schematic  diagram  of  managing  biophysiochemical  pathways  of  soil organic  C  accumulation  in  agricultural  lands  in  cooler  and  warmer climates.(Image  by  Xiangbi  Chen)