Energy use and carbon footprint from lawn management : A case study in the Uppsala region of Sweden

Abstract: Atmospheric concentrations of greenhouse gas emissions are now higher than ever before, with severe implications for both humans and ecosystems around the world. To mitigate climate change, large and sustained reductions of greenhouse gas emissions are required. The management of lawns entail frequent maintenance activities, such as mowing, irrigation and fertilisation, which require energy and cause greenhouse gas emissions. Lawns cover a significant part of urban areas worldwide, with functions such as air quality improvement, flood mitigation and the potential to sequester carbon and consequently reduce carbon dioxide (CO2) from the atmosphere. The existing knowledge about the environmental impact from lawn management is limited and more research is needed to determine related climate effects. The objective of the study was to evaluate energy use and carbon footprint from urban lawn systems with different intensities through a life cycle perspective. The lawns included in the study consisted of utility lawns and meadow lawns, with management under responsibility of Uppsala municipality, and the two golf courses Upsala GK and Sigtuna GK, divided into the lawn types greens, tees, fairways and roughs. The energy use and carbon footprint was determined by an inventory of the existing lawn management practices through interviews with greenkeepers at the golf courses, stakeholder at Uppsala municipality and lawn caretakers. Additional information for the inventory was received from literature and databases. Based on the inventory, calculations of the energy use and carbon footprint throughout the life cycle was made. The results showed that greens had the largest carbon footprint and energy use per hectare followed by tees, fairways, roughs, utility lawns and meadow lawns. The energy use was the highest for the golf courses, with 16.5 GJ ha-1 year-1 for Upsala GK and 13.0 GJ ha-1 year-1 for Sigtuna GK. Lower energy use was determined for the utility lawns and meadow lawns, where 3.0 and 0.5 GJ ha-1 year-1 were required for the lawn management, respectively. The carbon footprint of the golf courses was 1.33 Mg CO2- equivalents (CO2e) ha-1year-1 for Upsala GK and 0.94 Mg CO2e ha-1 year-1 for Sigtuna GK, which was larger compared to the utility lawns of 0.2 Mg CO2e ha-1 year-1 and meadow lawns of 0.03 Mg CO2e ha-1 year-1. Mowing, irrigation and manufacturing of fertiliser were the management activities consuming most energy. The activities with largest carbon footprint were mowing, manufacturing of fertiliser and soil emissions from application of fertilisers. This study was a part of a multidisciplinary research programme, where the results will be used to determine the net emission balance when the carbon sequestration potential of the lawns has been concluded. Suggested improvements at the golf courses were to reduce the applied amounts of nitrogen fertiliser and improve the documentation of used resources. Increasing the usage of hybrid and electrical mowers was recommended for both the municipality as well as the golf courses to reduce the energy use and the carbon footprint.