Multifunctionality-solving approaches of compost application in crop rotations

Compost is usually applied once at the beginning of a cropping plan and provides fertilization to several crops. The paper focuses on the way of distributing compost burdens (environmental and economic) among those crops in a real Mediterranean rotation. Four approaches were proposed and compared to solve that multifunctionality problem, according to the hierarchy recommended by the ISO 14044. The rotation included four crops: chard, tomato, cauliflower, and onion; and two fertilizing options: mineral fertilizers (M) and mineral fertilizers plus compost (CM). Life cycle assessment was used for the environmental assessment, and standard farm accounting for the economic one. Compost production had very relevant responsibility for the total impacts of the option using compost, CM. Therefore, the choice of the multifunctionality-solving approach for compost burden distribution had major effects on the results. The compost was a very modest contributor to the total costs; therefore, the divergences on the economic results due to the solving approach were small. Among the four solving approaches, subdivision according to nitrogen mineralization rates and physical allocation related to nitrogen uptake seemed to be the best options. Both approaches had a tight causal relationship with the amount of nitrogen consumed; however, only the physical allocation was based on the specific data obtained during the study.