Impact of grazing regime on legume-based swards for low-input farming

Organic grassland farming and sustainable agricultural systems need swards able to produce more or less stable yield within seasons and over several years. Different swards composed of selected components from Trifolium repens L., Medicago sativa L., Lolium perenne L. and Poa pratensis L. were investigated during 1999-2004 on a loamy Cambisol under low-input fanning. All swards were grazed using two more and less intensive regimes. The species composition of the sward and grazing frequency had a significant effect on sward yield and quality. The yield of legumes in mixed swards accounted for nearly half of the total sward yield, and in the swards with lucerne even more than half. Legume yield declined annually in both grazing frequencies but to a greater extent under frequent grazing. Lucerne/grass and white clover/lucerne/grass swards showed the highest stability during each grazing season over four years under both grazing frequencies. Dry matter yield was more stable under the less frequent grazing treatment, but more equal distribution of yield during the grazing season was observed in the frequent grazing management. The positive impact of five years less frequent grazing on lucerne-based swards was significant in the 6(th) year with identical grazing in all treatments.