Objective  The paper aimed to determine the influence of biodegradable plastic film mulching on soil organic carbon pool and aggregates, so as to provide a theoretical basis for improving soil quality and realize the reduction and replacement of ordinary plastic mulching.

  Method  Based on a field experiment carried out in garlic fields in Pizhou, Jiangsu Province from October 2021 to June 2022, the random block design was adopted, and three treatments were set up: no mulching (CK), polyethylene plastic film mulching (PM) and biodegradable plastic film mulching (BM). The contents of soil organic carbon pool in 0-20 cm soil layer and water stable aggregates of different particle sizes were analyzed.

  Result  Compared with CK, both PM and BM had no significant effect on soil total organic carbon content. Compared with PM, BM treatment could significantly increase the content of soil dissolved organic carbon and easily oxidized organic carbon, but significantly reduce the content of microbial biomass carbon. Under the three different treatments, the proportion of water stable aggregates with particle size > 5 mm was the largest, accounting for 33.65%-37.85%. Compared with CK, PM and BM treatments significantly increased the average weight diameter and geometric average diameter of aggregates, but had no significant effect on the fragmentation rate of aggregates. With the increase of particle size, the organic carbon content of soil water stable aggregates increased first and then decreased, with the highest particle size of 0.5-1 mm. Except for water-stable aggregates with particle size > 5 mm and 3-5 mm, the organic carbon content of water-stable agglomerates with other particle sizes was significantly higher than that of CK or PM under BM treatment.

  Conclusion  Under the short-term condition, fully biodegradable plastic film mulching can improve the soil structure of garlic field, increase the content of soil active organic carbon and water stable aggregate organic carbon with particle size > 0.25 mm, and help to improve the soil quality.