Unveiling carbon dynamics in year-round waterlogged pond fields: insights into soil organic carbon accumulation and sustainable management

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Agri-ecosystems with flooded fields are pivotal in global carbon (C) dynamics. Although extensive research has focused on carbon sequestration in paddy fields, year-round waterlogged pond fields remain underexplored. This study investigates carbon dynamics in pond fields planted with Semen Euryales for 0, 24, and 60 years, examining soil organic carbon (SOC) accumulation and shifts in its composition. The results revealed a progressive increase in SOC, driven by particulate organic C (POC) and mineral-associated organic (MAOC). SOC increased significantly from 7.49 g kg–1 to 46.10 g kg–1 over the 60 years, with particulate organic carbon (POC) rising from 12.0% to 42.0% and mineral-associated organic carbon (MAOC) decreasing from 87.8% to 58.0%. Lignin phenols, reflecting plant-derived carbon, surged from 11.0% to 68.8%, while amino sugars, indicative of microbial residues, declined from 89.0% to 31.2%, suggesting reduced microbial activity under prolonged anaerobic conditions. Total microbial phospholipid fatty acid (PLFA) decreased by 40.6% and 43.8% after 24 and 60 years, respectively, further supporting the conclusion that anaerobic conditions limit microbial survival. The prolonged waterlogging reduced microbial decomposition, enhancing the accumulation of POC, particularly from plant-derived carbon such as Semen Euryales residues. The accumulation of microbial residues, especially fungal necromass, played a significant role in forming MAOC. That is, continuous waterlogging promoted POC accumulation and also contributed to MAOC stabilization. The findings provide valuable insights into sustainable carbon management practices in pond fields and contribute to climate change mitigation.Graphical