Multifunctionality of Biochar From Wood Gasification: Control of Pesticide Dynamics and Early Plant Growth

Introduction: Biochar can play a relevant role in the soil‐plant system by affecting both the dynamics of agrochemicals and plant growth. This study investigated the potential of a poplar wood biochar produced at 850°C to control the retention and leaching of the long‐persistent fungicide boscalid (BOS) in soil and the early growth of agricultural plants. Materials and Methods: Biochar characterization included advanced analyses such as inductively coupled plasma‐atomic emission spectroscopy (ICP‐AES), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and Brunauer‐Emmet‐Teller (BET) analysis. BOS adsorption/desorption was evaluated by performing sorption kinetics and isotherms, and by modeling the experimental data with various theoretical equations. Bioassays on horticultural plants were also conducted. Results: Adsorption studies demonstrated a noticeable and rapid retention of BOS on biochar according to a pseudo‐second order kinetic model, which denoted the contribution of chemisorption. The adsorption isotherms of BOS fitted well the Freundlich model and showed distribution coefficients (Kd) values of 5.5, 23.5 and 28.3 mg g−1 at interaction temperatures of 10, 20°C and 30°C, respectively. A minimal release of BOS was observed after four desorption cycles, indicating a long‐term retention of the compound on biochar. Leaching experiments in soil columns showed that the addition of 1, 2% and 5% biochar was effective in countering the downward movement of BOS, and that such activity was directly proportional to the dose. Bioassays on cucumber and sunflower treated with 0.04% and 0.1% (w/v) biochar did not show inhibitory effects, but rather a stimulation of root elongation of cucumber at the higher dose. Conclusion: The overall results obtained confirmed the multifunctionality of this material, which, in a context of sustainable agriculture and soil health protection, can play a substantial role in controlling the dynamics of organic xenobiotics in soil without exerting inhibitory effects on the tested plants.