Influence of Hedge Pruning Returning on Soil CO2 Flux in Subtropical China

There is an increasing attention to the effects of agroforestry systems on agricultural sustainability and greenhouse gas emissions in recent years. We examined soil CO₂ fluxes under different hedgerow pruning management practices (removed from plots (AR), incorporated into soil (AI) and applied as mulch (AM)) in Vetiver-wheat intercropping system on a loamy clay soil, in subtropical China. Some potential factors such as soil temperature, rainfall, water-filled pore space (WFPS) and crop biomass were also measured during wheat crop cultivation. The results showed that soil CO₂ fluxes revealed distinct seasonal dynamics, with the highest values being observed during the heading stage of crop growth, while the lowest fluxes were observed during the overwintering stage. Furthermore, significant differences in soil CO₂ fluxes were observed among the three hedgerow pruning managements during the wheat growing period, following the order of VI> VR > VM. Cumulative soil CO₂ fluxes were estimated as 9265.01, 7598.72 and 5659.30 kg C hm^-2 for VI, VR and VM, respectively. Compared to removal of pruning, incorporation of pruning increased soil CO₂ fluxes, while the opposite trend was observed from surface-applied pruning. In this study, soil temperatures, especially at depth 10 cm, and wheat growth were the major factors influencing soil CO₂ fluxes during the entire growing period, while no significant correlation between soil CO₂ flux and WFPS was observed. As a result, hedge pruning returning to soil can, in turn, influence soil temperature and crop growth, which can further alter the magnitude of soil CO₂ flux in the present environmental conditions to some extent.