Greenhouse gas emissions in coffee grown with differing input levels under conventional and organic management

Coffee plays a key role in sustaining millions of livelihoods around the world. Understanding GHG emissions from coffee supply chains is important in evaluating options for climate change mitigation within the sector. We use data from two long-term coffee agroforestry experiments in Costa Rica and Nicaragua to calculate carbon footprints (CF) for coffee and identify emission hotspots within different management systems, levels of inputs and shade types. Management system and input level were the main cause of variation in CFs. Carbon footprints for 1 kg of fresh coffee cherries were between 0.26 and 0.67 kgCO2e for conventional and 0.12 and 0.52 kgCO2e for organic management systems. The main contributor to GHG emissions for all management systems was the inputs of organic and inorganic nitrogen. Nitrous oxide emissions from pruning inputs contributed between 7% and 42% of CFs. However, these estimates were strongly influenced by the choice of emission factor used in the calculations. Research is required to develop emission factors that account for different qualities and management of nitrogen inputs to enable effective calculation of the CF from different management strategies, and especially from the pruning and organic inputs managed in agroforestry systems. As such, effective climate change mitigation strategies can only be developed from site-specific studies which utilise accurate accounting and regional-specific emission factors.