Sustainable productivity of soil agricultural use and Jevons’ Paradox. Past and future myths

According to W.S. Jevons, the efficiency of a resource use tends to increase, rather than decrease, its consumption rate. This is particular true in the thermo-economics processes. In this note, the authors try to apply this proposition to explain the global trend of progressive impoverishment of the soil, especially in the western societies, and the rise of many environmental problems due to a high-inputs agriculture and to poor impact assessment and participatory methods. In fact, even a “technologically optimistic” scenario, using, for example, Georgesçu-Roegen’s Promethean technologies (such as, in a more modern view, genetic engineering, biotechnologies and renewable energy supplies), for enhancing a better use of agriculture resources and factors, could lead to an increment of productivity in the short period, but, at the same time, to unsustainable practices in the middle-long period (such as biodiversity decrement and natural flow inversion of biosphere evolution, a non-renewable resources depletion, alterations of hydro-geological cycles and microclimate modifications).