Soil carbon dynamics and greenhouse gas balance: implications of sugarcane straw removal for bioenergy production

Abstract

Bioenergy production, particularly liquid biofuels, has been promoted as a mean to enhance energy security and reduce climate change impacts. Additionally, the growing demand for energy for the next few years has intensified investments in technologies capable of using crop residues as raw material for bioenergy production. Sugarcane straw has enormous potential for use in industry to maximize the production of second generation ethanol (2G) and/or bioelectricity. However, while straw removal for bioenergy production can be advantageous from the point of view of energy security, otherwise, maintaining this raw material in the field ensures the continued provision of ecosystem services such as improved soil quality and biomass production. The objective of this project is to evaluate the effects of straw removal on the temporal dynamics of soil carbon (C) stocks, taking into account the peculiarities of soil, climate and crop management in the south-central region of Brazil. Our challenge is to identify and contrast sustainable removal scenarios in relation to the potential of greenhouse gases (GHG) mitigation when using this material for bioenergy purposes. In order to achieve the desired outcomes, the proposal will be implemented in three phases, including medium-term field experiments and the use of mathematical modeling (DayCent) to simulate and predict the implications of straw removal on soil C stocks on a long-term perspective, so that to identify recommended management practices that may mitigate the potential adverse effects of straw removal. Finally, these results will be integrated in the Virtual Sugarcane Biorefinery (VSB) in order to quantify the GHG balance associated with sucroenergetic sector in different scenarios of straw removal, taking into account all stages of the 2G ethanol production process and bioelectricity cogeneration. We believe that the results generated in this research could contribute to the formulation of public and sectoral policies that prioritize the sugarcane production and bioenergy towards greater sustainability. (AU)