III Agricultural data for life cycle assessments

An inventory for Life Cycle Analysis of agricultural products must address questions of representatively and coherence of models. This paper discusses the possibilities of modelling the input and production of typical farms to establish inventories that are consistent with higher level statistical information. Energy use has been modelled for typical Danish farms and compared with the national agricultural statistics. Expected differences in the use of fertiliser and pesticides and in the yields of 12 different types of crop rotations on two groups of soil types were modelled on the basis of 13,000 detailed farm accounts. The overall representatively and consistency were checked against regional and national statistical information based on other sources and in case of larger differences than 25%, the models were adjusted. Partial models of emissions in single enterprises should be adjusted or calibrated against consistent data or models of farm types on the one side and against aggregated statistics at a higher level on the other side. This might be done for the losses of N and P using a balance approach. For emissions like greenhouse gasses or heavy metals, where no sector specific aggregated measurements exist, the emissions might be estimated directly from the input inventory. Following the proposed procedure might secure consistent models of input and emissions for a representative set of farm types and none of the tasks should be omitted without clear indication and explanation.