Energy analysis of organic arable farming systems: the impact of the level of intensification

The study reveals significant variability in the key parameters of the energy analysis applied to 44 organic crop rotations, each lasting four years. The level of intensification of the systems, assessed in terms of whether or not organic fertiliser is used on cereals and whether irrigation is used on summer crops (mainly grain legumes), largely explains this variability. Average energy consumption ranges from 5,000 to 12,270 MJ/ha/year depending on the level of intensification. Energy production ranges from 35,500 to 43,950 MJ/ha/year. As energy consumption and production vary in the same direction with the degree of intensification, the energy gain remains stable at an average of 29,300 MJ/ha/year. Energy efficiency decreases from 7.1 MJ/MJ for unfertilised and unirrigated crop rotations to 3.5 MJ/MJ for fertilised and irrigated crop rotations, in which soya and field beans play a significant role.