For organic crop production, well-characterised varieties increase the possibilities for controlling diseases and weeds and compensating for deficits in nutrients. Variation in grain yield was studied in about 150 spring barley varieties and variety mixtures and 20 combinations of location, growing system and year. Choice of variety was found to be as important a factor for grain yield as other factors in the management. Some variety mixtures out yielded even the best variety in the mixture, when this was grown in pure stand. Finally, a concept for organic variety testing of spring barley was developed. This Danish project is part of a European COST Network on sustainable low-input cereal production (SUSVAR) which coordinates studies in different countries on variety mixtures, composite crosses and variety testing
