Since sugarcane areas have increased rapidly in Brazil, the contribution of the sugarcane production, and, especially, of the sugarcane harvest system to the greenhouse gas emissions of the country is an issue of national concern. Here we analyze some data characterizing various activities of two sugarcane mills during the harvest period of 2006-2007 and quantify the carbon footprint of sugar production.

Soil organic carbon (SOC) plays an important role for soil quality and its conservation is affected by the land-use change (LUC) associated with sugarcane (Saccharum officinarum) expansion. This study was based on the hypothesis that: (i) LUC from perennial crops (e.g., coffee and citrus) and extensive pasture to sugarcane plantation results in depletions of soil carbon (C) stock and its quality; and (ii) transition of annual crops to sugarcane increases soil C stock and improves its quality. Therefore, the objective of this study was to assess changes in soil C stocks and the humification levels of soil organic matter (SOM) upon conversion of different land uses (coffee, citrus, annual crop and pasture) into sugarcane plantation in the Mococa region, northeast of São Paulo state, southern Brazil. The experiment was conducted within commercial farms and experimental design is comprised of a farming system involving four scenarios of land-use transition to sugarcane (e.g., paired areas). Soil samples were collected to a 1-m depth (0?10,10?20, 20?60 and 60?100 cm), and the equivalent layers of 0?20 and 0?100 cm were obtained for each paired area. SOC decreased in 3 years ranged from 124.5 to 99.8 Mg C ha-1 for the 0?100 cm layer following the conversion of coffee to sugarcane. Conversion of citrus to sugarcane depleted soil C stock from 147.7 to 113.1 Mg C ha-1 for the 0?100 cm layer after a 4-year period. Conversion of pasture into sugarcane was comparatively less adverse in terms of soil C stocks, with depletion only for the 0?20 cm layer from 30.3 to 17.0 Mg C ha-1 in 8 years. Regarding the conversion from annual crop to sugarcane, there was no difference in soil C stock among land uses at any soil depths. Laser-Induced Fluorescence Spectroscopy (LIFS) showed a high stage of humification of SOM with increase in the magnitude of depletion of soil C stock, and vice versa. Increases in humification stages of SOM were observed from the top to the deepest layers for most of the land-use systems. Overall, conversions of perennial tree crops (e.g., coffee and citrus) into sugarcane increased the humification levels of SOM in sub-soil, except when sugarcane replaced pasture. The latter had lower humification of SOM in the surface layers of soil because of intensive tillage associated with sugarcane planting operations. Thus, the short-term maintenance of straw had a minor impact in improving soil C accumulation as well as reversing the increased oxidation level of SOM induced by sugarcane expansion. Further, our study suggests the need of assessing the impacts of LUC on soil C budget to deep sub-soil layers in agricultural systems. Finally, the data indicate that expansion of sugarcane over coffee and citrus agrosystems may impact the sustainability of ethanol production because of LUC-induced depletion of soil C stock and degradation of soil quality

There is a growing need for all productive sectors to develop greenhouse gas (GHG) mitigation techniques to reduce the enhanced greenhouse effect. However, the challenge to the agricultural sector is reducing net emissions while increasing production to meet growing demands for food, fiber, and biofuel. This study focuses on the changes in the GHG balance when sugarcane areas are converted from burned harvest (BH) to green harvest (GH, mechanized harvest), including the changes caused by the adoption of conservationist practices such as reduced tillage and a 4‐month crop rotation with Crotalaria juncea L. during sugarcane replanting. Based on the Intergovernmental Panel on Climate Change (IPCC) (2006) methodologies, the annual emission balance includes both agricultural and mobile sources of GHG, according to the mean annual consumption of supplies per hectare. The potential soil carbon accumulation was also considered in the GH plot. The total amounts of GHG were 2651.9 and 2316.4 kg CO₂eq ha⁻¹ yr⁻¹ for BH and GH, respectively. Factoring in a mean annual soil carbon accumulation rate of 888.1 kg CO₂ ha⁻¹ yr⁻¹ due to the input from long‐term crop residues associated with the conversion from BH to GH, the emission balance in GH decreased to 1428.3 kg CO₂eq ha⁻¹ yr⁻¹. A second decrease occurs when a reduced tillage strategy is adopted instead of conventional tillage during the replanting season in the GH plot, which helps reduce the total emission balance to 1180.3 kg CO₂eq ha⁻¹ yr⁻¹. Moreover, the conversion of sugarcane from BH to GH, with the adoption of a crop rotation with Crotalaria juncea L. as well as reduced tillage during sugarcane replanting, would result in a smaller GHG balance of 1064.6 kg CO₂eq ha⁻¹ yr⁻¹, providing an effect strategy for GHG mitigation while still providing cleaner sugar and ethanol production in southern Brazil.