| Abstract |
CONTEXT: A mismatch between nutrient demand and consumption in livestock and cropping systems makes these sectors responsible for 24.5% of greenhouse gas emissions. In order to reduce the gap between the two industries, approaches focused on integrating livestock and crop management have been presented. Location is a key factor in the sustainable operation of these integrated systems since this variable affects both the economic and environmental dimensions of the design of the farm.OBJECTIVE: In this work, a two-step methodology is proposed to address simultaneously the formulation of the feed, the design of the nutrient recovery process, the location of the facilities, and its size, from economic and environmental points of view.METHODS: First, prescreening is used to discard locations that do not meet a series of environmental constraints. Next, an optimization framework is developed by integrating empirical models that estimate the nutritional needs of the animals, fertilizer consumption, waste production, as well as the effect of selection of locations and the size of the farm on the objective function. The farm is designed to produce the feed on the premises and animal wastes are used to produce fertilizers and biogas, implementing the circular economy. The optimization framework is used to estimate the optimal feed formulation, crop selection, size and location, following a multi -objective approach.RESULTS AND CONCLUSIONS: The methodology is applied to a case study in Spain. Of the 345 agricultural districts considered, 145 are discarded in the prescreening. The optimal number of initial animals is 1000. The results show that the selection of 'Bureba-Ebro' and a crop distribution that consumes 12% less nutrients than the economic scenario, results in the reduction of 35% in the environmental impact. In addition, meat production cost is 8.87 euro /kg (1.6 euro /kg corresponds to the waste treatment). Nevertheless, it can be reduced down to 1.51 euro /kg by considering the income from crop sales.SIGNIFICANCE: Only through this integrated framework it is possible to determine the feed formulation and facility location that best balance the economic and environmental objective, and determines the percentage of nutrients that can be recovered. The methodology is generic enough to be applied to other locations, crops, and animals. |