Eco-energetics analysis of an agricultural system: The French case in 1970

摘要: Abstract Eco-energetics analysis is used to describe structure and functioning of the French agricultural system. Data are for 1970. For energy inputs, most costly items these related motor driven equipment chemical fertilizers. 153.7 MGJ (megagigajoule = 1015 joules) due use carburants (energy directly used) 53.8 indirect energy. fertilizers, 149.7 used, principally production nitrogenous These two items, represent a combined value more than 60% total inputs: one likely find similar values system in industrialised countries. Other such as construction, buildings electricity not negligible, 41.2 15.1 respectively. Concerning outputs plant products, major part animal feed; this represents 1,441.2 which added 15 imported products. half consumption (720 MGJ), source crops with very high input, artificial grassland, fodder cereals; grain cereals (217.7 MGJ) items. Furthermore, only important export from at 142.3 MGJ. human crop products supply gain 177.2 43.7 meat, 37 milk 2.5 eggs. In sub-system “husbandry”, rearing activities (70.7 must be consumed (378.2 feed processing (47.2 MGJ). Energy devoted food 180 The input 596.5 MGJ, 4.2 man power 8.4 power. food, needs 1.45 units produce unit: it better other modern systems. Efficiency work equals 94: figure logically all systems Sixty-eight per cent comes imports. Economies realized positive action could done by different ways: avoid overequipping quick obsolescence materials; foster adoption systematic rotations; fertilizing possibilities plants nitrogen-fixating symbionts, manure organic wastes; study carefully advantages close rearing-crops relationships.