Fig. 4. Dry matter yields of a perennial ryegrass–white clover mixture and a herbal ley mixture (23 species of grasses, legumes, and forbs) compared with perennial ryegrass fertilized with 400 kg N ha^–1 under sheep grazing in New Zealand. The herbal ley and grass monoculture did not differ in yield, whereas both treatments yielded more than the grass–clover mixture. Data are from Ruz-Jerez et al. (1991). LSD = least significant difference.