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

Abstract

SUMMARY Two 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.