Life cycle assessment shows that integrating nut trees reduces carbon footprint of soybean farming

Abstract

Agroforestry systems enhance productivity, resource-use efficiency, and climate resilience, offering a promising pathway for integrating soybean ( Glycine max L. Merr.), European hazelnut ( Corylus avellana L.) and sweet chestnut ( Castanea sativa Mill.) into sustainable farming systems. This study employed a cradle-to-farm gate life cycle assessment, focusing on the climate change impact (carbon footprint) only due to its relevance as a key environmental indicator in agroforestry systems, to assess the climate change impacts and productivity of soybean monoculture, nut tree systems, and soybean–nut agroforestry in western Slovakia. Three agroforestry configurations were assessed using the IPCC (2021) GWP 100 method, with biogenic carbon uptake in tree biomass modelled as negative CO 2 flows. Integrating soybeans with nut trees consistently reduced net greenhouse gas emissions, with total GWP 100 ranging from − 8.8 to − 17,122 kg CO 2 -eq ha −1 , and modelled soybean yields ranging between 416 and 979 kg ha −1 . Compared to conventional soybean monoculture (CAS), GWP was reduced by 68–101% (hazelnut) and 1,020–1,265% (chestnut), with yield declines of 61–83%. Sweet chestnut-based systems achieved the largest GWP reductions through modelled woody-biomass accumulation, whereas soybean–hazelnut systems retained higher modelled soybean yields but achieved smaller GWP reductions. Nut production provided an additional agricultural output. Overall, soybean–nut agroforestry systems show potential for climate mitigation alongside agricultural production under the assumptions of this study.

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