Finding the right compromise between productivity and environmental efficiency on high input tropical dairy farms: a case study.

This study focused on the trade-off between milk production and its environmental impact on greenhouse gas (GHG) emissions and nitrogen surplus in a high input tropical system. We first identified the objectives of the three main stakeholders in the dairy sector (farmers, a milk cooperative and environmentalists). The main aim of the farmers and cooperative's scenarios was to increase milk production without additional environmental deterioration but with the possibility of increasing the inputs for the cooperative. The environmentalist's objective was to reduce environmental deterioration. Second, we designed a sustainable intensification scenario combining maximization of milk production and minimization of environmental impacts. Third, the objectives for reducing the eco-inefficiency of dairy systems in Reunion Island were incorporated in a framework for activity analysis, which was used to model a technological approach with desirable and undesirable outputs. Of the four scenarios, the sustainable intensification scenario produced the best results, with a potential decrease of 238 g CO2-e per liter of milk (i.e. a reduction of 13.93% compared to the current level) and a potential 7.72 L increase in milk produced for each kg of nitrogen surplus (i.e. an increase of 16.45% compared to the current level). These results were based on the best practices observed in Reunion Island and optimized manure management, crop-livestock interactions, and production processes. Our results also showed that frontier efficiency analysis can shed new light on the challenge of developing sustainable intensification in high input tropical dairy systems.