Effect of straw biochar application on soil carbon, greenhouse gas emissions and nitrogen leaching: A vegetable crop rotation field experiment

Abstract

Intensive vegetable crop systems are rapidly developing, with consequences for greenhouse gas (GHGs) emissions, nitrogen leaching and soil carbon. We undertook a field trial to explore the effect of biochar application (0, 10, 20 and 40 t ha−1) on these factors in lettuce, water spinach and ice plant rotation. Our results show that the 20 and 40 t ha−1 soil treatments resulted in the SOC content being 26.3% and 29.8% higher than the control (0 t ha−1), respectively, with significant differences among all treatments (p < .05). Biochar application caused N2O emissions to decrease during the lettuce and water spinach seasons, by 1.5%–33.6% and 12.4%–40.5%, respectively, compared the control, with the 20 t ha−1 application rate resulting in the lowest N2O emissions. Biochar also decreased the dissolved nitrogen (DN) concentration in leachate by 9.8%–36.2%, following a 7.3%–19.9% reduction in dissolved nitrogen in the soil. Similarly, biochar decreased the nitrate (NO3−) concentrations in leachate by 3.9%–30.2%, following a 3.8%–16.7% reduction in the soil nitrate level. Overall, straw biochar applied at rate of 20 t ha−1 produced the lowest N2O emissions and N leaching, while, increasing soil carbon.

Biochar use in agriculture as a nature-based solution: factors influencing N>small<>sub<2>/small<>/sub<O emissions in tropical soils

“…The most significant reduction was seen in soils amended with sugarcane straw biochar, where N2O emissions were 50% lower than in NF (Figure 12 B). This finding corroborates with studies that have observed suppression of N2O emissions caused by straw-based biochars (Abbruzzini et al, 2019;Hamad et al, 2023;Zhang et al, 2022). Conversely to previous studies that reported no reductions in soil N2O emissions in response to woody biochar application (Lan et al, 2019;Ramlow et al, 2019), we observed that both wood-based biochars reduced N2O emissions.…”