Biodegradable　plastics,　as　an　alternative　to　petroleum　plastics,　are　fiercely　increasing,　but　their　incomplete　degradation　under　natural　conditions　may　lead　to　the　breakdown　into　microplastics　(MPs).　Here,　we　explored　the　impacts　of　chicken　manure-derived　(MBC)　and　wood　waste-derived　biochar　(WBC)　on　the　degradation　of　polylactic　acid　microplastics　(PLA-MPs)　during　soil　incubation　for　one　year.　Both　biochars　induced　more　pronounced　degradation　characteristics　in　PLA-MPs,　including　enhanced　surface　roughness,　the　proportion　of　MPs　4+　via　Fe2+-driven　NO3-/NO2-　reduction　and　microbial　nitrogen　fixation,　and　oxidative　degradation　by　radicals　generated　through　Fenton/Fenton-like　reaction.　WBC　caused　aminolysis/ammonolysis　and　oxidative　degradation　mainly　through　dissimilatory　nitrate　reduction　to　ammonium　and　surface　free　radicals　on　biochar.　These　findings　indicate　that　biochar　has　the　potential　to　accelerate　PLA-MP　degradation,　and　its　regulatory　mechanism　depends　on　the　type　of　biochar.　©　2024　Elsevier　B.V.