Greenhouse gas assessment of soybean production: implications of land use change and different cultivation systems

Abstract The increase in soybean production as a source of protein and oil is being stimulated by the growing demand for livestock feed, food and numerous other applications. Significant greenhouse gas (GHG) emissions can result from land use change due to the expansion and cultivation of soybean. However, this is complex to assess and the results can vary widely. The main goal of this article is to investigate the life-cycle GHG balance for soybean produced in Latin America, assessing the implications of direct land use change emissions and different cultivation systems. A life-cycle model, including inventories for soybean produced in three different climate regions, was developed, addressing land use change, cultivation and transport to Europe. A comprehensive evaluation of alternative land use change scenarios (conversion of tropical forest, forest plantations, perennial crop plantations, savannah and grasslands), cultivation (tillage, reduced tillage and no-tillage) and soybean transportation systems was undertaken. The main results show the importance of land use change in soybean GHG emissions, but significant differences were observed for the alternative scenarios, namely 0.1–17.8 kg CO2eq kg−1 soybean. The original land choice is a critical issue in ensuring the lowest soybean GHG balance and degraded grassland should preferably be used for soybean cultivation. The highest GHG emissions were calculated for tropical moist regions when rainforest is converted into soybean plantations (tillage system). When land use change is not considered, the GHG intensity varies from 0.3 to 0.6 kg CO2eq kg−1 soybean. It was calculated that all tillage systems have higher GHG emissions than the corresponding no-tillage and reduced tillage systems. The results also show that N2O emissions play a major role in the GHG emissions from cultivation, although N2O emission calculations are very sensitive to the parameters and emission factors adopted.

[1]  R. DeFries,et al.  Decoupling of deforestation and soy production in the southern Amazon during the late 2000s , 2012, Proceedings of the National Academy of Sciences.

[2]  T. Ponsioen,et al.  Calculating land use change in carbon footprints of agricultural products as an impact of current land use , 2012 .

[3]  Thiago Libório Romanelli,et al.  Material embodiment and energy flows as efficiency indicators of soybean (Glycine max) production in Brazil , 2012 .

[4]  Olaf Christen,et al.  Long-term productivity and environmental effects of arable farming as affected by crop rotation, soil tillage intensity and strategy of pesticide use: A case-study of two long-term field experiments in Germany and Denmark , 2008 .

[5]  Pål Börjesson,et al.  Agricultural crop-based biofuels – resource efficiency and environmental performance including direct land use changes , 2011 .

[6]  Enrique Ortega,et al.  Brazilian Soybean Production: Emergy Analysis With an Expanded Scope , 2005 .

[7]  N. Halberg,et al.  LCA of soybean meal , 2008 .

[8]  H.M.G. van der Werf,et al.  Methods and data for the environmental inventory of contrasting pig production systems , 2007 .

[9]  P. Rochette,et al.  Towards a Revised Coefficient for Estimating N2O Emissions from Legumes , 2005, Nutrient Cycling in Agroecosystems.

[10]  Shelie A. Miller,et al.  Life cycle of the corn-soybean agroecosystem for biobased production. , 2007, Environmental science & technology.

[11]  T. Bruulsema,et al.  Review of greenhouse gas emissions from crop production systems and fertilizer management effects , 2009 .

[12]  Vamilson Prudêncio da Silva,et al.  Variability in environmental impacts of Brazilian soybean according to crop production and transport scenarios. , 2010, Journal of environmental management.

[13]  Shelie A. Miller,et al.  Minimizing land use and nitrogen intensity of bioenergy. , 2010, Environmental science & technology.

[14]  K. Hayashi,et al.  Variability in environmental impacts during conversion from conventional to organic farming: a comparison among three rice production systems in Japan , 2012 .

[15]  M. Huijbregts,et al.  Biogenic greenhouse gas emissions linked to the life cycles of biodiesel derived from European rapeseed and Brazilian soybeans , 2008 .

[16]  Wim Turkenburg,et al.  Large-scale bioenergy production from soybeans and switchgrass in Argentina: Part B. Environmental and socio-economic impacts on a regional level , 2009 .

[17]  Mareike Lange,et al.  The GHG Balance of Biofuels Taking into Account Land Use Change (Power Point) , 2011 .

[18]  Enrique Ortega,et al.  Integrated environmental assessment of biodiesel production from soybean in Brazil , 2010 .

[19]  B. Dale,et al.  Regional variations in greenhouse gas emissions of biobased products in the United States—corn-based ethanol and soybean oil , 2009 .

[20]  C. Cederberg,et al.  The interaction between milk and beef production and emissions from land use change – critical considerations in life cycle assessment and carbon footprint studies of milk , 2012 .

[21]  A. Patyk,et al.  Energie- und Stoffstrombilanzen der Düngemittelbereitstellung , 1997 .

[22]  Sebastião Roberto Soares,et al.  Comparison of the ecological footprint and a life cycle impact assessment method for a case study on Brazilian broiler feed production , 2012 .

[23]  Roland Clift,et al.  A Life-Cycle Approach to Characterising Environmental and Economic Impacts of Multifunctional Land-Use Systems: An Integrated Assessment in the UK , 2010 .

[24]  E. Stehfest,et al.  Global scale DAYCENT model analysis of greenhouse gas emissions and mitigation strategies for cropped soils , 2009 .

[25]  Shelie A. Miller,et al.  A comparative life cycle assessment of petroleum and soybean-based lubricants. , 2007, Environmental science & technology.

[26]  E. Gnansounou,et al.  Life cycle assessment of soybean-based biodiesel in Argentina for export , 2009 .

[27]  Arnaldo Walter,et al.  The energy balance of soybean biodiesel in Brazil: a case study , 2011 .

[28]  T. Friedrich.  Does No-Till Farming Require More Herbicides? , 2005 .

[29]  Francesco Cherubini,et al.  GHG balances of bioenergy systems – Overview of key steps in the production chain and methodological concerns , 2010 .

[30]  Theocharis Tsoutsos,et al.  Life Cycle Assessment for biodiesel production under Greek climate conditions , 2010 .

[31]  Hong Huo,et al.  Life-cycle assessment of energy use and greenhouse gas emissions of soybean-derived biodiesel and renewable fuels. , 2009, Environmental science & technology.

[32]  Shelie A. Miller,et al.  Use of Monte Carlo analysis to characterize nitrogen fluxes in agroecosystems. , 2006, Environmental science & technology.

[33]  Shelie A. Miller,et al.  Using DAYCENT to quantify on-farm GHG emissions and N dynamics of land use conversion to N-managed switchgrass in the Southern U.S. , 2011 .

[34]  Prem S. Bindraban,et al.  Changes in organic carbon stocks upon land use conversion in the Brazilian Cerrado: a review. , 2010 .

[35]  N. Halberg,et al.  Environmental assessment of organic soybean (Glycine max.) imported from China to Denmark: a case study , 2010 .

[36]  Timothy D. Searchinger,et al.  Estimating Greenhouse Gas Emissions from Soy-based US Biodiesel when Factoring in Emissions from Land Use Change , 2008 .

[37]  Detlef P. van Vuuren,et al.  Contribution of N2O to the greenhouse gas balance of first‐generation biofuels , 2009 .

[38]  Brenda Chang,et al.  Estimating life cycle greenhouse gas emissions from corn–ethanol: a critical review of current U.S. practices , 2009 .

[39]  Enrique Ortega,et al.  Emergy, nutrients balance, and economic assessment of soybean production and industrialization in Brazil , 2009 .

[40]  Rainer Zah,et al.  Global environmental consequences of increased biodiesel consumption in Switzerland: consequential life cycle assessment , 2009 .

[41]  F. Freire,et al.  Life-cycle GHG assessment of soybean biodiesel , 2012, 2012 IEEE International Symposium on Sustainable Systems and Technology (ISSST).

[42]  B. Gabrielle,et al.  Environmental impact of the substitution of imported soybean meal with locally-produced rapeseed meal in dairy cow feed , 2009 .

[43]  Mark A. J. Huijbregts,et al.  Nitrous oxide emissions from liquid biofuel production in life cycle assessment , 2011 .

[44]  Eros Comunello,et al.  From forest to waste: Assessment of the Brazilian soybean chain, using nitrogen as a marker. , 2008 .