Embodied energy in agricultural inputs. Incorporating a historical perspective

This working paper analyzes the energy embodied in agricultural inputs from a historical perspective. The study is based on a wide literature review, which has been complemented with own estimations in order to create a coherent database including all direct and indirect energy associated to the main agricultural inputs with the maximum possible level of disaggregation. The inputs studied include human labour, energy carriers such as fuels and electricity, materials, machinery, synthetic fertilizers and pesticides, organic inputs, propagation material, irrigation inputs, buildings, greenhouses, transport and non-material services. For each input we describe its historical evolution from an energetic perspective, the most common methods used for the calculation of its embodied energy published in the literature and temporal data series on the historical evolution of this energy. The temporal data series are expressed in 10-year time-steps and, in the majority of cases, they cover the whole 20th century and the first decade of the 21st century. The values provided are global averages or covering the main producing regions. The results show the large changes that have occurred in the energy efficiency of the production of agricultural inputs, underlining the need for the use of dynamic coefficients in historical energy analyses of agricultural systems.