Agroscope, Institute for Plant Production Sciences IPS, 1260 Nyon, Switzerland

DOC-trial: yields and energy use efficiency

Between 1978 and 1998 a bio-dynamic, a bio-organic and a conventional farming system were compared in the DOC-field-trial on a luvisol on Loess at Therwil, Switzerland. Nutrient input (N, P, K) in organic systems was about 50 % lower than in the conventional system. Yields of marketable potatoes showed the strongest reduction after conversion to organic farming. During the first 7-year crop rotation period potato yields decreased to 70Ê % and later on to 50 % of the yield of the conventional system. For wheat and clovergrass yield decrease in the organic systems was more slowly. In the second and third crop rotation the organic systems produced about 80 % respectivly 90 % of the wheat yields of the conventional system. Clover-grass yields of organic systems remained at 90 % in the second period but decreased to 75 % in the organic and 83 % in the biodynamic system in the third crop rotation period. In organic systems direct and indirect energy use to produce one ton of crop was higher for potatoes, but lower for winterwheat and clover-grass than in the conventional system.

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