Triple impact: Biochar, no-tillage, and cover crops for soil carbon enhancement and climate resilience in soybean farming

Abstract

With the dissemination of conservation agriculture, no-tillage (NT) and cover crops have widely been adopted globally. However, their effects on greenhouse gas (GHG) emissions are controversial. Biochar is posited to mitigate climate change by increasing carbon (C) sequestration and decreasing GHG emission in soil. To investigate the comprehensive effect of NT, cover crops, and biochar on soil organic carbon (SOC) sequestration and net global warming potential (GWP), a split-split-plot experiment was conducted. The experiment involved various combinations of two tillage methods (NT; Moldboard plowing, MP), two cover crop treatments (Fallow, FA; Rye, RY), and two biochar treatments (with biochar application, WB; no biochar application, NB). NT and RY demonstrated a trend of increasing N2O emission, while WB tended to reduce the N2O emission in NT plots. NT–RY–WB increased the SOC stock (0–30 cm) by 23.2% in 2020 and 30.2% in 2021 compared with MP–FA–NB, indicating that this combination promoted C sequestration. Due to the heightened SOC stock, the net carbon dioxide (CO2) retention effectively compensated the GWP arising from non-CO2 emissions. Consequently, the triple combination of NT, RY and WB positively contributed to a decreased net GWP in the soybean field (−1231 kg CO2 equivalent ha−1 year−1 in 2020 and −2767 kg CO2 equivalent ha−1 year−1 in 2021). These findings highlight the considerable potential of the combined NT–RY–WB for SOC sequestration and net GWP decrease, positioning it as an environmentally beneficial agricultural system for mitigating climate change in Asia’s long-term food production.