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DOC-Trial: Comparing farming systems. Oestergaard, T.V. 1996

Alfoldi, TH.; Besson, J.-M.; Dubois, D.; Mader, P.; Niggli, U.; Pfifner, L.

The three farming systems bio-dynamic, bio-organic and conventional have been compared in a field experiment at Therwil, Switzerland during two seven year crop rotation periods (CRP) from 1978 until 1991. Crop yield and food quality as well as effects on soil processes have been evaluated.

Physical soil conditions were not affected by the farming systems. Soluble phosphorus and potassium availability in the biologically treated soils were 40% lower than in the conventional treatment reflecting the differences in potassium and phosphorus input. However, differences in fixed element fractions were much smaller.

Soil microbial biomass, activity and diversity of earthworms, carabids, spiders and staphylinids in the biological treatments was higher than in the conventional treatment. (Further details see conference contribution of Maeder et al.).

Whilst yields of both organic systems (average of all crops) during the 1st CRP were only 12% lower than in the conventional production system, during the 2nd CPR yields were 25% lower in the bio-dynamic and 20% lower the bio-organic system. Potato yield in the biologically cultivated plots was 40%, beetroots 25%, cereals 15% and grass-clover 10% lower than in the conventional plots.

The energy balances of the cropping systems were compared in order to describe their efficiency in the use of energy. In order to produce one crop unit, the energy use in the biological systems was 15-30% lower, except for potatoes. This difference was mainly caused by a lower input of indirect energy for fertilizer and pesticide production.

Product quality as described by its content in minerals, amino acids, protein and sugars as well as the technological quality were not affected significantly by the treatments. However, holistic methods for quality visualisation, like the picture developing method, allowed for a distinct grouping and identification of encoded samples.