Sunflower Husk Biochar as a Key Agrotechnical Factor Enhancing Sustainable Soybean Production

Climate change has a decisive impact on the physical parameters of soil. To counteract this phenomenon, the ongoing search for more effective agri-technical solutions aims at the improvement of the physical properties of soil over a short time. The study aimed to assess the effect of biochar produced from sunflower husks on soil respiration (SR), soil water flux (SWF), and soil temperature (ST), depending on its dose and different soil cover (with and without vegetation). Moreover, the seed yield was assessed depending on the biochar fertilization. Field experiments were conducted on Calcaric/Dolomitic Leptosols (Ochric soil). SR, ST, and SWT were evaluated seven times in three-week intervals during two seasons, over 2018 and 2019. It was found that the time of biochar application had a significant effect on the evaluated parameters. In the second year, the authors observed significantly (p < 0.005) higher soil respiration (4.38 µmol s−1 m−2), soil temperature (21.2 °C), and the level of water net transfer in the soil (0.38 m mol s−1 m−2), compared to the first year. The most effective biochar dose regarding SR and soybean yield was 60 t ha−1. These are promising results, but a more comprehensive cost-benefit analysis is needed to recommend large-scale biochar use at this dose.