Practical recommendations for supporting agricultural decisions through life cycle assessment based on two alternative views of crop production: the example of organic conversion

Earlier studies on agricultural life cycle assessment recommend that practitioners use two functional units-product weight and land area-because agriculture entails commodity production and land use. However, there are still ambiguities in this approach from the perspective of decision support. The purpose of this paper is to provide recommendations to support farming conversion decisions on the basis of a framework constructed on two alternative views of agricultural production. Organic conversion of arable farming is selected as a case study. Four types of conversion were constructed on the basis of land-oriented expression, in which inputs into and outputs from land were depicted, and product-oriented expression, in which inputs into and outputs from products were depicted. Then, the frequencies for each type were counted using LCI databases and data from journal papers. The results can be summarized as follows: (1) trade-off conversion, in which improvements in environmental impacts per area unit are involved in decrease of yield per area unit, is common. (2) Conversion tended to be efficient; that is, environmental impacts per product unit tended to improve. (3) Within trade-off conversion, the conversion tended to be efficient. (4) When conversion was efficient, there were trade-offs. Since the results for one expression were not always derivable from the results for another expression, the recommendation of this study is to use the two expressions complementarily, knowing that win-win conversion is rare. In addition, there is a general recommendation to use decision criteria rather than trying to make decisions on the basis of multiple functional units because comparisons based on the two functional units are not on the same level.