ENVIRONMENTAL ASSESSMENT OF DEMARCATED BED-GROWN ORGANIC GREENHOUSE TOMATOES USING RENEWABLE ENERGY

Abstract

The environmental impacts associated with fossil energy use, in addition to water and fertilization management continue to be major concerns for Northern greenhouse production systems. To reduce the environmental impacts of greenhouse farming under Northern climate conditions and to maintain its competitiveness, the use of renewable energy sources and suitable nutrient management are becoming essential. From this perspective, a closed-loop demarcated bed-grown organic production system that increases the efficiency of water and nutrient use and utilizes waste biomass as a source of energy was developed and tested in the province of Quebec, Canada. The goal of this study was to assess the environmental impacts of this so-called sustainable organic system compared with an open conventional growing system using fossil energy. The environmental analysis was conducted with life cycle assessment methodology as defined by the ILCD handbook (2010) and the SimaPro v.7.3.2 software. The functional unit was 1,000 kg of tomatoes and 1 ha of cultivated area. The system boundary was from raw materials extraction to the farm gate. The life cycle stages considered were infrastructure, auxiliary equipment, climate control system, farm operation, fertilizers, pesticides, waste management and packaging. For both growing systems, results from the environmental assessment indicate that high energy demand was the main contributor to all impact categories. When organic farming using wood biomass as renewable energy was applied, the CO2 footprint of 1 kg of tomatoes was 0.812 kg CO2 eq kg-1, while the impact of an open conventional growing system using fossil energy was 5.788 kg CO2 eq kg-1. The fertiliser assessment of the closed-loop organic crop had a lower environmental burden on abiotic depletion (by 12 times), acidification (by 6 times), eutrophication (by 136 times) and global warming (by 10 times) compared with the fertiliser assessment of the open conventional growing system.