Book of Abstracts
11th IFOAM
Scientific Conference
11-15 August 1996
Copenhagen, Denmark

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Symposia

DOC-Trial: Comparing Farming Systems S19

Alfoeldi, T.1 ; Besson, J.-M.2 ; Dubois, D.3 ; Maeder, P.1 ; Niggli, U.1 & Pfiffner L.1

1) Research Institute of Organic Agriculture, CH-4104 Oberwil; 2) Institute of Environmental Protection and Agriculture, CH-3097 Liebefeld-Bern; 3)Swiss Federal Research Station for Agroecology and Agriculture, CH-8046 Zurich.

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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 (CPR) 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.

Fertilisers and the C- and N-dynamics in Soil S19

Bachinger, J. Centre for Agricultural Landscape and Land Use Research e.V. (ZALF), Müncheberg Institut for Land Use Systems and Landscape Ecology, Eberswalder Str. 84, D-15374 Müncheberg

Knowledge of the influence of the microbial biomass, root growth and dynamics of carbon (humus) and their interactions with the N-dynamics using different fertilisation methods is very important in order to optimize the nitrogen nutrition of non-legume crops and to estimate the sustainability of organic farming systems. The following results refer to a research program from 1988-1991 at the Institute of Biodynamic Research, Darmstadt. Investigations were based on a long-term experiment which started in 1980 on a sandy orthic luvisol with three types of fertilisation (I: NPK, II: composted manure, and III: composted manure and liquid manure as well as biodynamic manure and spray preparations) and three different fertilisation intensities (1 = 50/60 kg N/ha, 2 = 100 kg N/ha, 3 =140/150 kg N/ha).

This long-term experiment is suitable for studying these important questions, because it offers the opportunity of examining the influence of different kinds of fertilisation (mineral and organic) and fertilisation intensities as well as the influence of biodynamic preparations. Tests were carried out to investigate the effects of organic matter and different mineral and organic N-fractions, soil microbiological parameters and root growth of winter rye with regard to their temporal dynamic and spatial distribution.

After the early years of the experiment (1980-1982) there was a significant differentiation in soil organic carbon. Mineral and organic fertilisation differed significantly as did the organic (II) and biodynamic (III) fertilisation. These differences stabilised in the following years and reached the following values by 1990: I = 0.81 a; II = 0.90 b; III = 1.04 c; and 1 =0.87 a; 2 = 0.91 ab; 3 = 0.96 b ( P). Microbial and root parameters were affected by fertilisation to a similar extent as the organic matter. Differences between treatments II and III were more pronounced in the subsoil (25-55 cm). In contrast to these results the soil nitrate content and the yields of treatments II and III did not differ.