Book of Abstracts
11th IFOAM Scientific Conference
11-15 August 1996, Copenhagen, Denmark
Agricultural Research Centre of Finland Research Station for Ecological Agriculture Partala FIN - 51900 Juva
One of the main reasons for consumers to buy products derived from ecological agriculture is the health aspect. Ecological products are expected to have a superior nutritional quality compared with the conventional ones. The interpretation of results from comparative studies strongly depends on the researcher's conception of quality. Optimization of product quality in ecological agriculture requires both basic research in the quality criteria and testing of products from different practical farming conditions.
At the Research Station for Ecological Agriculture in Juva, Finland, a research project on product quality was started in 1994. The project which cooperates with the extension, control and education services for ecological agriculture in Finland, has two aims, i.e. to optimize farming methods in ecological agriculture in terms of quality and, second, to select and develope control criteria for the quality of ecological products. Fertilization is one of the main factors affecting the product quality in different farming practises. In a three-year field trial with potato and carrots, the effects of four fertilizer types (composted manure, fresh manure, aerated slurry, mineral fertilizer) are being studied at three fertilization levels. The effect of biodynamic preparations is tested on the solid manure plots. The aftereffect of fertilizing on soil and subsequent crops (wheat and ley) is studied in crop rotation. Potato and carrot samples from ecological farms, as well as data on the farming practises and local conditions are collected in order to detect other important factors affecting the product quality on farm level.
Various quality tests on potato and carrots are carried out, including chemical analyses e.g. for vitamin, mineral and nitrate contents, as well as storage tests, sensory evaluation and so-called holistic methods. Further evaluations include nitrogen dynamics in soil and plant, as well as biological parameters in soil, such as microbial decomposition, earthworm density and mycorrhizal activity. Relationships between different parameters are studied by using multivariate statistics.
Preliminary results from the field trial in 1995 show a positive correlation between the amount of mineral nitrogen in the fertilizer and the nitrate content in the product and nitrate left in the soil after harvest. The free amino acid content, protein content and extract dissolution rate of potato were highest and starch and dry matter contents were lowest in the treatments with mineral fertilizer. Composting of solid manure had a positive effect on the percentage of marketable yield and the vitamin C content of potato. Soil dehydrogenase activity tended to be highest after the treatment with composted manure. Yet, conclusions from the effects of organic fertilizers and the relationships between different quality characteristics can be drawn only after several years of study.