Response of Pure Stands and Mixtures of Cereals and Legumes to Nitrogen Fertilization and residual effect on subsequent barley

Abstract

SUMMARYTwo rotation field experiments of a single forage–cereal cycle each were conducted on a clay loam soil (Vertic Cambisols) in Cyprus in 1982–85. The forages in the first cycle (1982–84) were pure stands of vetch (Vicia saliva L.), peas (Pisum sativum L.) and oats (Avena sativa L.) and mixtures of each of the two legumes with oats at sowing ratios of 90:10, 75:25, 50:50 and 25:75 grown with 15, 30, 60, and 90 kg fertilizer N/ha. For the second cycle (1983–85) the same crops were used but with only two mixture ratios (legume:oats 90:10 and 75:25), and with 0, 15, 45 and 90 kg N/ha. Barley (Hordeum vulgare L.) was the test crop after the forages in both cycles. Legumes did not respond to N fertilization, whereas the yields of the pure stand of oats and the mixtures increased. The legumes yielded more N but less dry matter than the cereals. The grain and N yields of barley were higher after legumes than after oats, with intermediate yields after the mixtures. Barley responded to residual N fertilizer, irrespective of whether it was applied on legumes, oats or mixtures in the previous year. When choosing the forage to be grown, farmers should consider (a) the need for roughage and protein, (b) the costs of N fertilizer for crops and of protein for animal feed stuff and (c) the rotational role of the crop.