Eco-efficiency determinants: a new approach combining an agronomic whole–farm model and efficiency frontier analysis

The growing awareness on the multiple environmental impacts of livestock production has risen the necessity to widen the definition of efficiency to a multidimensional eco-efficiency concept. Our paper suggests a combined approach of a whole-farm agronomic model and frontier efficiency method to explore deeply the determinants of eco-efficiency. The whole-farm model used, GAMEDE, is randomly parameterized for key management practices and structural parameters in order to generate a large dataset of simulated dairy systems in La Réunion Island. Upper and lower bounds fixed for the stochastic choice of parameter values are a key point in the approach and relies on expert knowledge derived from participatory modeling. For each simulation, numerous indicators describing the functioning and the performance of the production system are model-based calculated and some of them (inputs, outputs and undesirable ouputs) are chosen to define the production technology in a frontier efficiency analysis. The frontier efficiency method used, data envelopment analysis, provides a multidimensional synthetic eco-efficiency score. It represents the potential outputs raise, with no increase in inputs and undesirable outputs. The eco-efficiency score can be linked to all the indicators of the production system calculated by the whole-farm model and it becomes possible to characterize accurately the factors (managerial, structural, economic, agro and zootechnical, etc) explaining ecoefficiency levels. In our study case, dairy farming in La Réunion, livestock production is strongly constrained by land scarcity. Consequently most eco-efficient farms appear to be intensive systems with important forage productivity to ensure their alimentation self-sufficiency. While most efficiency studies are restricted to narrow data set, the proposed methodology is innovative as it allows to cover the realm of possible livestock production systems in a given territory and characterize them, at low cost in time and money, with a large range of descriptive variables. Coupling whole–farm models and efficiency frontier analysis is a promising methodology to better identify the eco-efficiency determinants and the ecological intensification pathways.