Assessing the potential of biochar to enhance maize productivity and soil organic carbon sequestration under future climate scenarios in Togo

Abstract

Ensuring food security has become a major challenge in the face of climate change impacts on agricultural systems, leading to soil fertility decline and reduced crop yields. To investigate the potential of biochar, three field experiments were conducted from July 2022 to January 2024 at the research station of the Togolese Institute for Agronomic Research, the Center of Agronomic Research of the Littoral (ITRA/CRAL) based in Davié across three growing seasons. To leverage our analysis, we used the data to calibrate and evaluate a process-based crop model (DSSAT-Ceres) and applied it to estimate the implications of biochar use under future climate projections. The application of 20 t ha-1 of biochar (B20) significantly increased SOC concentration by 2.20 g kg-1. Meanwhile, B10 and C1 did not significantly influence SOC. The effect on soil total nitrogen from different treatments was not significant. Grain yield increased significantly with biochar application at a rate of 20 t ha⁻¹ during the second season, while the positive effect was marginal in the third growing season. After calibration, the DSSAT-Ceres model showed an RMSE of 0.16% and 0.09%for biomass and SOC, respectively. The future projections at the Davié site showed an increase in temperature of 1.27°C equivalent to 4.58% under the optimistic scenario (SSP126) and 2.05°C which is equivalent to 7.38% under the pessimistic scenario (SSP585) across almost all the 5 GCMs selected in this study, but a +6.67 mm increase under the SSP126 scenario and -12.99 mm decrease in rainfall. If crop management remains the same, maize yields are projected to decrease by 0.84% to 13.03% under the optimistic and 9.05% to 24.11% under the pessimistic scenarios for the years 2040-2070. However, this was not statistically significant. Similarly, the SOC is projected to decrease by 0.11% to 3.47% under the optimistic scenario (SSP126) and decrease by 0.89% to 5.26% under the pessimistic scenario (SSP585). When biochar is integrated as management practice (C0F0B20), the yields and SOC could be increased by 374.38 % and 73.38 %, respectively, as compared to low-input practice (e.g., C0F0B0) in average for historical and future scenarios. If combined with compost and mineral fertilizers, the increase in yield and SOC is higher (483.98 and 80.82%) as compared to low-input, but when compared to C1F1B0 the effect on yields is small (12.83%) whereas SOC increases considerably (20.54%). The model should be improved to capture the management practices and residual effects of soil organic amendments to give a representation close to reality.