Effects of including nitrogen emissions from soil in environmental systemsanalysis of waste management strategies

The environmental impacts of nitrogen emissions from soil resulting from th e use of organic fertilizers, such as manure, are large compared with the c orresponding impacts of mineral fertilizers. However, soil emissions are ra rely included in systems analysis of waste management strategies. This stud y examines whether the inclusion of soil emissions can affect the environme ntal ranking of systems for managing solid biodegradable waste. Waste manag ement scenarios based on incineration, anaerobic digestion and composting, respectively, were compared. The scenarios were analysed using the organic waste research (ORWARE) simulation model. A simplified model for calculatin g nitrogen availability and emissions was also constructed. Life-cycle anal ysis methodology was used for choosing system boundaries and evaluating the results. Global warming, acidification and eutrophication were the impact categories considered. The results indicate the vital importance of conside ring nitrogen emissions from soil when comparing biological waste managemen t systems with other waste management methods, especially with regard to eu trophication effects. Soil emissions are also important when comparing the environmental impacts of anaerobic digestion and composting systems. Howeve r, the variation in nitrogen emissions from soil is large and depends on th e spreading technique used, climate, drainage and soil texture (C) 1998 Els evier Science B.V. All rights reserved.