Agrosilvopastoral and silvopastoral systems can increase carbon sequestration, offset greenhouse gas (GHG) emissions and reduce the carbon footprint generated by animal production. The objective of this study was to estimate GHG emissions, the tree and grass aboveground biomass production and carbon storage in different agrosilvopastoral and silvopastoral systems in southeastern Brazil. The number of trees required to offset these emissions were also estimated. The GHG emissions were calculated based on pre-farm (e.g. agrochemical production, storage, and transportation), and on-farm activities (e.g. fertilization and machinery operation). Aboveground tree grass biomass and carbon storage in all systems was estimated with allometric equations. GHG emissions from the agroforestry systems ranged from 2.81 to 7.98 t CO2e ha−1. Carbon storage in the aboveground trees and grass biomass were 54.6, 11.4, 25.7 and 5.9 t C ha−1, and 3.3, 3.6, 3.8 and 3.3 t C ha−1 for systems 1, 2, 3 and 4, respectively. The number of trees necessary to offset the emissions ranged from 17 to 44 trees ha−1, which was lower than the total planted in the systems. Agroforestry systems sequester CO2 from the atmosphere and can help the GHG emission-reduction policy of the Brazilian government.

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RESUMOA carência de estudos sobre o balanço de carbono e viabilidade econômica em sistemas agroflorestais (SAF) motivaram este estudo. Foram avaliados um sistema agrissilvipastoril (SASP) composto por eucalipto, feijão e capim braquiária e um sistema silvipastoril (SSP) composto por eucalipto e capim braquiária, ambos aos 3 anos de idade. Para estimar a biomassa do componente arbóreo foi utilizado o método indireto e para a gramínea, o direto. As emissões de gases de efeito estufa (GEE) foram baseadas no guia de Inventários Nacionais de GEE. Carbon Balance and Economic Viability in Two Agroforestry Systems inViçosa, MG ABSTRACTThe lack of studies on carbon balance and economic viability in Agroforestry Systems (AFS) motivated this study. We evaluated an agrosilvopastoral system (SASP), composed of Eucalypt, beans and Brachiaria-grass; and a silvopastoral system (SSP), composed of Eucalypt and Brachiariagrass, both 3 years old. The tree biomass was estimated using the indirect method and the direct method was used to quantify the grass biomass. Greenhouse gas (GHG) emissions were based on the National Inventory tab of GHGs. The Net Present Value (NPV) and Internal Rate of Return (IRR) were calculated. Both systems had a positive carbon balance. The NPV in the SASP was $388.77 and the IRR was 21%. The positive results were due to revenue generated by the sale of beans. The SSP NPV was -$ 1,298.00 and the IRR of -2%, considering the 3 years old trees cutting.