Energy Efficiency in Agrarian Systems From an Agroecological Perspective

Energy analyses applied to agriculture should express something more than the energy cost of the net biomass produced for the benefit of society. They should also provide information about structural and functional changes in the agroecosystem which might affect the maintenance of the ecosystem services which the agroecosystem provides. With this aim, a methodological proposal has been developed to add agroecological EROIs (energy return on the investment) to the existing economic EROIs. This proposal has been applied to an agroecosystem which is representative of Mediterranean agro-climatic conditions at three key moments: one of balanced organic agriculture (1752), at the beginning of the use of chemical inputs (1904), and a time of agricultural production decoupled from its territory (1997). The results demonstrate the usefulness of the combination of both types of EROI in the detection of processes (agriculturalization vs. livestock farming, reforestation, generation of spatial heterogeneity, or the maintenance of biodiversity), which affect the fund elements of agroecosystems and their capacity to generate flows of ecosystem services.