Inventorying Greenhouse Gas Emission Due to Harvest Practices in Sugarcane Areas of South Central, Brazil.

Increasing biofuels use is an alternative to fossil fuels, which helps to reduce greenhouse gas (GHG) emissions to atmosphere. Sugarcane ethanol has proved to promote up to 90% of GHG emission reduction compared to gasoline (IEA, 2007). However, changes in land management, especially in harvest practices could influence the GHG emissions related to the sugarcane in agricultural phase. This study estimates the GHG emissions due to sugarcane harvest practices, contrasting burned and green harvest, in sugarcane areas of South Central region, Brazil. Estimations were performed considering the period from 2006 until 2011, applying IPCC (2006) methodologies. The GHG emissions were associated with the following sources: i) sugarcane residue burning; ii) N₂O emissions from sugarcane residues left on soils after green harvest; and iii) emission from diesel consumption by harvesting operations. The methodology used to follow the harvest status, as performed either with burning or non-burning practices, uses MODIS satellite data acquired from April to December of each year. Our estimates indicate that total sugarcane areas available for harvest increased from 4.6 to 7.7 Mha during the 2006-2011 period, corresponding an increase of 67%. On the other hand, the total emissions related to the harvest practices raise only 33%, from 5.8 to 7.7 Mton CO₂eq, respectively. Considering total GHG emission per area, our estimates point out a reduction of more than 20% in the studied period, from 1.25 to 0.99 ton CO₂eq ha^-1. This reduction is due to the conversion from burned to green harvest, in which the contribution of pre-harvest burning in total sugarcane area decreased from 61 to 27%. This study suggests that ethanol production from sugarcane could easily more sustainable if non-burning practices could be implemented in all production area.