Nitrous oxide and methane emissions are affected by soil tillage systems and crop diversity in the Brazilian Savanna
crossref(2023)
摘要
<p>Population growth associated with the increasing demand for resources around the globe has increased greenhouse gas (GHG) emissions, leading to the climate change process. In this study, we assessed the impact of agrosystems intensification on N<sub>2</sub>O and CH<sub>4</sub> emissions in the Brazilian Savanna. We selected two long-term experiments located in Costa Rica – MS and Itiquira – MT, which consisted of soil tillage systems (conventional (CT) and no tillage (NT) systems) and levels of crop diversification with cover crops (e.g., <em>Brachiaria</em> sp., <em>Crotalaria</em> sp., <em>Pennisetum</em> sp.) in soybean-cotton-based cropping systems. Gas emissions were monitored for 8 months (February 2022 to October 2022). N<sub>2</sub>O and CH<sub>4</sub> fluxes were calculated following the linear changes in the concentration of each gas, and cumulative emissions were estimated after extrapolation from hourly to daily fluxes. Data were subjected to analysis of variance, and means were compared by Tukey's test (p<0.05). In Costa Rica - MS, CH<sub>4</sub> fluxes varied between -30 and 50 µg m<sup>-2</sup> h<sup>-1</sup> of CH<sub>4</sub>-C and were greatly affected by rainfall seasonality. Cropping systems affected cumulative emissions, with soybean + cotton under CT and soybean + cotton + maize presenting emissions of 0.13 and 0.27 kg ha<sup>-1</sup> of CH<sub>4</sub>-C, respectively. Soybean + cotton under NT and the treatments with cover crops (soybean + cotton + <em>Brachiaria</em> sp., and soybean + cotton + rattlebox) promoted CH<sub>4</sub> uptake, sequestering up to 0.6 kg ha<sup>-1</sup> of CH<sub>4</sub>-C. N<sub>2</sub>O fluxes were mostly affected by N fertilization. Peaks up to 270 µg m<sup>-2</sup> h<sup>-1</sup> of N<sub>2</sub>O-N were observed, most associated with soybean + cotton + maize treatment, and soybean + cotton under CT. The highest cumulative N<sub>2</sub>O emissions were observed at soybean + cotton + maize and soybean + cotton + <em>Brachiaria</em> sp. treatment (0.88 kg ha<sup>-1</sup> of N<sub>2</sub>O-N on average). Soybean + cotton under CT and NT systems, and soybean + cotton + rattlebox showed an average cumulative emission of 0.43 kg ha<sup>-1</sup> of N<sub>2</sub>O-N. At Itiquira – MT, CH<sub>4</sub> fluxes also were affected by rainfall seasonality, with values ranging between -40 and 90 µg m<sup>-2</sup> h<sup>-1</sup> of CH<sub>4</sub>-C. Cumulative CH<sub>4</sub> emissions were significantly affected by the treatments, with the highest emissions at soybean + maize succession (i.e., 0.36 kg ha<sup>-1 </sup>of CH<sub>4</sub>-C). The succession between soybean + <em>Brachiaria</em> sp. and the other crop rotations involving rattlebox and millet did not differ from each other, presenting an average uptake of 0.13 kg ha<sup>-1 </sup>of CH<sub>4</sub>-C. For N<sub>2</sub>O-N, the fluxes were highly responsive to N fertilization in maize, presenting peaks up to 75 µg m<sup>-2</sup> h<sup>-1</sup> of N<sub>2</sub>O-N. Cumulative N<sub>2</sub>O emissions, however, were reduced (0.18 kg ha<sup>-1 </sup>of<sup> </sup>N<sub>2</sub>O-N) only at soybean + rattlebox + maize + <em>Brachiaria</em> sp., which was 2.7 times lower than the cumulative emissions found at soybean + maize, soybean + <em>Brachiaria</em> sp., and soybean + rattlebox + maize + <em>Brachiaria</em> sp. for one year period. Overall, our results suggest that cropping intensification in the Brazilian Savanna is an efficient strategy to reduce CH<sub>4</sub> and N<sub>2</sub>O emissions, contributing to tackling the climate change process. </p>
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要