Over a period of seven years farmers participated in trials in which common vetch (Vicia sativa (V)) or chickling (Lathyrus sativus (C)) replaced the fallow in a barley (Hordeum vulgare)–fallow rotation (F) or were introduced into continuous barley cropping (B) – giving a total of four rotations, B–F, B–B, B–V and B–C. Trials on 4 ha, 2 ha per phase of each rotation, were replicated on 6–8 farms. Some vetch and chickling crops were grazed in spring. Mean seven-year dry matter yields were 2.91 t ha−1 for B–F, 4.82 t for B–B, 5.02 t for B–C and 5.32 t for B–V; total crude protein outputs were twice as high from rotations including legumes; and the B–V rotation yielded most metabolizable energy. Realizing the benefit, farmers started to adopt vetch. In 1991 three farmers were growing vetch on 7 ha but by 1997 174 farmers in 15 villages were growing vetch on 420 ha. Forage legumes will not, however, become more widely grown until inexpensive and efficient mechanized methods of harvesting the mature crop are available in order to avoid the high cost of hand labour. Drought and cold tolerance, early maturation and high harvest index may also enhance farmers' interest in forage legumes.