Replacing the burnt sugarcane harvesting system with unburnt sugarcane is important for the sustainability of the sugarcane sector in Brazil. Thus, quantifying the impact of the change in the sugarcane harvesting system on soil organic carbon (SOC) stock in Brazil is necessary, as it will allow the refinement of data on SOC, which is essential for the preparation of the national inventory of emissions and removal of greenhouse gases (GHGs), in addition to contributing to national public policies. We used data from both soil sampling and literature review in this study, resulting in 210 pairs of comparisons: 84 for the conversion from burnt sugarcane to unburnt sugarcane; 95 for the conversion from native vegetation to unburnt sugarcane; and 31 for the conversion from native vegetation to burnt sugarcane (NV–burnt), which we analysed using a mixed linear model. In Brazil and the South‐Centre region, burnt–unburnt conversion results in a progressive increase in SOC stocks over time, in surface and subsurface layers. Over 20 years, the NV–burnt conversion showed SOC losses between 15% and 32%, and the NV–unburnt conversion showed losses between 27% and 35%. SOC change rates showed gains of 0.32 and 0.59 Mg C ha−1 year−1 for burnt–unburnt, and losses ranging from 0.82 to 1.06 Mg C ha−1 year−1 for conversions from native vegetation. The time required to offset the negative carbon balance of the NV–unburnt conversion is 6.4 and 8.2 years, being shorter than the payback time of the NV–burnt conversion, which is 9.9 and 9.2 years, in the 0–30 and 0–50 cm layers, respectively.

中文翻译：

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巴西的甘蔗收获系统：对土壤碳储量和乙醇投资回收期的影响


用未烧焦的甘蔗取代烧焦的甘蔗收割系统对于巴西甘蔗行业的可持续发展非常重要。因此，量化甘蔗收获系统的变化对巴西土壤有机碳 （SOC） 存量的影响是必要的，因为它将允许完善 SOC 数据，这对于编制国家排放清单和去除温室气体 （GHG） 至关重要，此外还有助于国家公共政策。在这项研究中，我们使用了土壤采样和文献综述的数据，得出了 210 对比较：84 对从烧焦的甘蔗到未烧焦的甘蔗的转化率;95 用于将原生植被转变为未燃烧的甘蔗;31 分表示从原生植被到烧焦甘蔗 （NV-burnt） 的转换，我们使用混合线性模型进行了分析。在巴西和中南部地区，烧毁-未烧毁的转化导致地表层和地下层的 SOC 储量随着时间的推移逐渐增加。20 多年来，NV 烧毁转换显示 SOC 损失在 15% 到 32% 之间，NV 未烧毁转换显示损失在 27% 到 35% 之间。SOC 变化率显示，烧毁-未烧毁的土壤有机碳变化率在 0.32 和 0.59 Mg C ha-1 年-1 之间增加，而原生植被的转换损失在 0.82 到 1.06 Mg C ha-1 年-1 之间。抵消 NV 未燃烧转化的负碳平衡所需的时间为 6.4 年和 8.2 年，短于 0-30 和 0-50 cm 层的 NV 燃烧转化的投资回收期，分别为 9.9 年和 9.2 年。