有機農業は環境にやさしいのか : 農業のLCAが示すこと

抄録

Many studies have been conducted for assessing the environmental impacts of organic agriculture. They compare, in general, a few agricultural systems including organic and conventional production. The comparison, however, raises several issues to be clarified from system thinking based on life cycle assessment (LCA). Therefore, this paper reviews applications of LCA to agriculture and presents the state of the art and some difficulties in the current studies. After surveying previous research projects and international conferences on agricultural LCA, applications of LCA to field crop production and horticulture are surveyed. Since the survey reveals the importance of utilizing multiple impact categories due to the existence of trade-offs between, for example, global worming and eutrophication, the relationship between environmental impacts of organic agriculture and impact categories in agricultural LCA is examined using previous LCA of wheat, in which data are gathered from field experiment. In addition, the problem with the selection of functional units is discussed because of the dependence of the results on the selection. The problem brings up a question how to cope with land in agricultural LCA and thus biodiversity and soil quality in agricultural LCA are reviewed. Finally, future research directions are presented for the development of agricultural LCA in Japan.