Nitrogen Fertilizer and Seeding Rate Influence on Grain and Forage Yield of Dual-Purpose Barley

Clipping fall-sown cereals provides a good source of high-quality forage during late winter. Farmers usually use more inputs, including fertilizers and seed, in dual-purpose systems compared with grain-only systems. A 2-yr field study was conducted in Karaj, Iran, to evaluate the effects of nitrogen (N) rates (0, 50, 100, 150 kg N ha(-1)) and seeding rates (400, 600, 800 seed m(-2)) on forage and grain yields of two barley (Hordeum vulgare L.) cultivars (Fasih and CB 744) in grain-only and dual-purpose systems. Fasih and CB 744 grain yields in the grain-only system were 2996 and 3250 kg ha(-1), respectively (averaged over experimental treatments). Forage removal in the dual-purpose system resulted in 25% grain yield penalty. Despite the lower grain yield, the economic return of the dual-purpose system was considerably greater due to the high price of forage during late winter in the region. Grain yield response to N was linear in the grain-only system, but the trend was not significant in the dual-purpose system. In both production systems, grain yield response to seeding rate was quadratic, and the highest yields of both cultivars (2534 and 3192 kg ha(-1) for Fasih and CB 744, respectively) were obtained from 600 seed m(-2). In both production systems, 600 seed m(-2) and 100 kg N ha(-1) were optimum for grain and forage production. Our results showed considerably higher revenue in the dual-purpose system compared with the grain-only system in this region. Moreover, no additional inputs of N and seed are required for dual-purpose barley than those usually used in a grain-only system.