Abstract

An energy analysis of agricultural practices shows very coherent patterns of evolution from the Neolithic Age up to this century. All technical advances were in fact exploited toward intensification, and the ratio of food output to energy input was held remarkably constant over such a long stretch of time. New agricultural practices in developed countries linked to massive energy “subsidies” from fossil fuels have disrupted the trend, altering substantially that ratio. A more attentive use of energy in agriculture is going to be necessary when the developing countries will adopt these practices. Low-tillage techniques, hormonal and genetic pesticides and herbicides, nitrogen fixing in grains, and other emerging technologies satisfying this constraint are briefly described and assessed in this paper. Using low tech procedures the top agricultural practice is the classical Chinese one where the food to sustain one person is produced in 100 square meters of land with no external support as mechanical energy and chemical fertilizers. It could be the solution to the hunger problems in low tech countries like Africa.