干旱区生态环境知识资源中心

Two barley cultivars (Hordeum vulgare L.) were grown at a site in semi-arid northeast Spain during three seasons, 1986-87, 1987-88, 1988-89, under two levels of N-fertilization (100 kg ha(-1), the normal dressing used in the area, and 50 kg ha(-1)). There was no benefit for yield from the higher rate of N fertilization; in 1987, a very dry season, the higher rate depressed yield. Nitrogen fertilization increased green area index and nitrogen uptake by the plant but did not affect any yield component. Harvest index was negatively affected by nitrogen in the driest year. The responses to nitrogen differed with cultivars. Rainfall amount and distribution of the year and probably the residual nitrogen in the soil strongly influenced the response to N-fertilization. It is concluded that less nitrogen fertilizer than at present used may improve the sustainability and stability of the cropping system without reducing the grain production in this area.