Carbon Footprint and Variable Costs of Production Components for a Container-grown Evergreen Shrub

Using an east-coast nursery scenario, the production components of an evergreen shrub (Ilex crenata ‘Bennett’s Compacta’) grown in a #3 container were analyzed for their costs and contributions to carbon footprint using Life Cycle Assessment (LCA) methods. A life cycle inventory included input materials, equipment use, and all cultural practices and other processes utilized in a model production system for this evergreen shrub. Greenhouse gas emissions (GHG) and their global warming potential (GWP; kg CO₂e), and variable cost of each component of the model system were determined. Transportation and transplanting of the final product in the landscape as well as its removal after a 40-year useful life were also included. GHG emissions from input products and processes during the production (cutting-to-gate) of the evergreen shrub were estimated to be 2.918 kg CO₂e. When considering carbon sequestration during production, weighted over a 100-year assessment period, the carbon footprint for this model system at the nursery gate was 2.144 kg CO₂e. Operations, combining the impact of material and equipment use, that contributed most of GHG emissions during production included fertilization (0.707 kg CO₂e), the liner and transplanting (0.461 kg CO₂e), the container (0.468 kg CO₂e), gravel and ground cloth installation (0.222 kg CO₂e), substrate materials and preparation (0.227 kg CO₂e), and weed control (0.122 kg CO₂e). The major contributors to GWP also added the most to the cutting-to-gate variable costs ($3.224) except for processes that required significant labor and little equipment investments. Post-harvest activities would result in GHG emissions of 0.376, 0.458 and 0 kg CO₂e for transporting the shrub to the landscaper, transporting it to the landscape site and transplanting it, respectively. Variable costs for post-harvest activities were $6.409 and were dominated by labor costs (90%). Analysis of nursery crop production systems using LCA has led to a greater understanding of the major contributing factors to GWP and variable costs. The cutting-to-landscape GWP of a container-grown evergreen shrub was estimated to be less than the accumulated, weighted impact of annual carbon sequestration during its useful life in the landscape. Such information will inform nursery managers and equip them for making better decisions on production protocols, market area, and ways to communicate the economic and environmental value of their products to the consuming public.