Biochar impact on soil properties and soil solution nutrient concentrations under cotton production

Intensive tillage and unsustainable agricultural practices adversely impact soil health and the long-term sustainability of crop production in humid subtropics. Biochar, a soil amendment, can be used to improve soil properties and agricultural productivity. A field experiment evaluated the impact of biochar application rates (B) (0, 10, 20, and 40 Mg ha^-1) on soil properties and soil solution chemistry under rainfed cotton (Gossypium hirsutum L.) production systems in the Lower Mississippi Delta from 2020 to 2022. An application of 40 Mg ha^-1 of biochar significantly reduced bulk density and increased water content in 0-15 cm compared to other rates and depths. Biochar increased aggregate stability compared to the control in the topsoil layer for aggregate fractions of size 0.5-1 mm and 1-2 mm in 2021. Biochar application at 20 and 40 Mg ha^-1 reduced NO₃-N concentration in soil by 63 % and 53 %, respectively, compared to the control at a 0-15 cm depth in 2021. Biochar applications reduced soil solution NO₃^--N losses 49 %-87 % and 42 %-102 % during the fallow period compared to the control at a 46 and 81 cm depth, respectively. Biochar also reduced the soil solution PO₄^3--P concentration 14 %-39 % compared to the control in the fallow period. Biochar improved soil properties while reducing nutrient losses in the soil solution and has the potential to be an alternative soil amendment strategy for sustainable cotton production.