Aerobic composting is an important technology for resource utilization, yet substantial greenhouse gas emissions and carbon–nitrogen losses limit its environmental benefits. Although biochar amendment has been widely applied, the stage-specific effects of electric field assistance on biochar-pig manure composting remain unclear. This study focuses on the effects of electric field application on the transformation of carbon and nitrogen during different stages of biochar-pig manure composting. The physicochemical properties of the compost pile, as well as the concentrations and forms of carbon and nitrogen, were analyzed. Four electric-field application treatments were established: continuous application throughout the whole composting period (E1), weeks 0–2 (E2), weeks 3–4 (E3), and weeks 5–6 (E4). The results showed that the total nitrogen contents in the electric field treatment groups were 20. 29–36. 58% higher compared to the initial level and significantly higher compared to CK (10. 91%). The cumulative NH3 emissions reduced by 44. 58–56. 23%, while N2O emissions declined by 8. 99–49. 29%. NH4+-N content was higher in E3 (electric field application during weeks 3–4), while NO3−-N content was higher in E4 (electric field application during weeks 5–6), indicating the optimal retention of nitrogen. In terms of carbon transformation, the cumulative emissions of CO2 and CH4 decreased by 6. 22–33. 49% and 3. 5–60. 35%, respectively. In addition, the electric field promoted organic matter degradation and aromatic substance accumulation, realizing efficient carbon sequestration. Meanwhile, it altered the structure of microbial communities, inhibited Pseudogracilibacillus, and activated norankfMWH-CFBk5, norankfFodinicurvataceae, as well as aerobic degraders such as Pseudomonadota. This study confirms that electric field treatment facilitates efficient waste resource utilization by optimizing the composting microenvironment and cutting greenhouse gas emissions. Treatment E1 exhibited the optimal carbon retention capacity, while treatments E3 and E4 showed the best nitrogen retention performance.
Zhang et al. (Sat,) studied this question.