Biogas residue - a safety risk in organic farming?

The Norwegian government aims to increase the organic food production and consumption to 15 % of the total within year 2015. To reach this ambiguous goal, it is estimated that of the total Norwegian agricultural area for each crop, approx. 18 % of the mea dow, 20 % of the pasture, 7,5 % of cereal, 15 % of vegetables, fruit and berries and 10 % of potatoes has to be organically managed in 2015, representing a total of 155 400 ha. The main challenge in organic plant crop and meat (sheep and beef cattle) prod uction is to attain high plant yields, because of lack of manure. Anaerobic digestion in biogas plants (BGP) is an alternative way to handle organic household waste, and there is an increasing interest in BGPs using food waste as energy source. The anaero bic digestion produces biogas (energy), and the biogas residue may be used as fertiliser in organic agriculture. Organic agriculture is based on the four principles (1) the principle of health, (2) the principle of ecology, (3) the principle of fairness a nd (4) the principle of care. These principles are the roots from which organic agriculture grows and develops. The project aims to contribute to fulfil The principle of ecology and The principle of care. The potential health risk with digested residues f rom BGPs is partly dedicated by the substrate being treated in the plant. It is well known that biowastes contain pathogenic bacteria such as Escherichia coli and Bacillus cereus, heavy metals, organic pollutants and pesticides. Biogas residue from anaer obic composting of household waste may be used in organic farming, but it is important to investigate the occurrence of bacteria (E. coli and B. cereus), heavy metals (cadmium, lead, mercury, nickel, zinc, copper, chromium), organic pollutants and pestici des in biogas residue and survival and growth of pathogenic bacteria on products (silage, cereal, dairy products), to ensure and acceptable quality of organically produced products.