Improving green-house gas balances of organic farms by the use of straight vegetable oil from mixed cropping as farm own fuel and its competition to food production

Mixed cropping is frequently used in organic farming and recommended worldwide in low external input areas to increase productivity, yield security and product diversity. In trials with different oil crops camelina (false flax, Camelina sativa L.), linseed (Linum ustitatissivum L.), rape (Brassica napus L.), safflower (Carthamus tinctorius L.) or white mustard (Sinapis alba L.) grown together with grain legumes or cereals on German sites the potential of renewable fuel production parallel to food production was evaluated in organic farming. Depending on the crop-combination between 10 to 900 kg/ha vegetable oil could be produced. This could cover the fuel demand of agricultural machinery for 0.1 to 9 ha farmland. The food crops combined with oil plants in mixed cropping mostly had relative yields higher as 0.5, showing that also yield increases in food production are possible parallel to the production of renewable fuel. As example for an introduction of a non-common oil crop in farm cycles, research results on the use of straight vegetable oil as fuel in tractors and of oil-cake as feedstuff for livestock from camelina are summarised. Based on the results the importance for the GHG emissions of organic farms is discussed. When mixed cropping systems with oil crops and the use of all products are consequently introduced, improvements in the GHG balance of farms can be expected by savings in production and yield stabilisation in mixed cropping as well as by direct substitution of diesel fuel in agricultural machinery and by substitution of imported feed components for livestock.