A multi–input multi–output model is developed by extending the life cycle assessment framework for analysing the relationship between agricultural production and environmental impacts. The inputs include farmland and materials such as fertilisers, pesticides and animals. The outputs are of two types: one is agro–economic production, such as crop yields, and the other is environmental impacts, including greenhouse gas emissions. Additive and ratio models are defined for analysing the relationship between management intensity, land productivity and environmental impacts based on the farm model. After the framework of multiple paired comparisons is illustrated, the multi–input multi–output model is applied to rice farming in Japan. The results indicate that the additive and ratio models can be used for detecting the directions of changes. These models can be extended for analysing the land–use competition between food and energy production.
Keywords: ecological assessment, economic assessment, life cycle assessment, LCA, multiple paired comparisons, management intensity, additive models, trade–offs, ratio models, eco–efficiency, rice production, modelling, MIMO models, multi–input multi–output, agricultural production, farmland, fertilisers, pesticides, animals, agro–economic production, crop yields, greenhouse gases, GHG emissions, land productivity, environmental impact, Japan, modelling, land use competition, food production, energy production