NITROGEN EFFECTS ON YIELD AND MALTING QUALITY OF BARLEY GENOTYPES UNDER NO-TILL

Conservation practices, such as reduced tillage and improved fertilizer use, are desirable from an environmental perspective and may yield economic benefits if production and quality are not impaired. This study was conducted to determine the effects of two N fertilization levels, 45 and 90 kg ha-1 (50 and 100% of normal grower rates), on yield and malting quality of spring barley (Hordeum vulgare L.) under no-till management. The study was conducted in 1986 and 1987 on a Palouse silt loam (fine-silty, mixed mesic Pachic Ultic Haploxeroll). Seven Nordic (Europe) genotypes were compared with four U.S. Pacific Northwest (PNW) cultivars. The higher N level increased grain yield across genotypes in both years (17% in 1986, 5% in 1987), reduced the percentage of plump kernels (4%) in 1987, and did not affect test weight, 1000-kernel weight, or percentage of thin kernels. All Nordic genotypes yielded less than the PNW cultivars except the Danish cultivar Nordal. Higher N increased total malt protein (7%) in both years and soluble malt protein (7%) in 1986. Higher N also significantly increased alpha-amylase (25%) and diastatic power (15%) in the malt, while malt extract was unaffected. Significant genotypic differences existed for all agronomic and malting parameters examined. Under no-till, HJA 78003 was the only Nordic genotype that produced good quality malt, equaling the three PNW malting cultivars under no-till. The higher N rate produced slightly better yield and quality than the reduced rate. Therefore, reducing the N rate to half the normal grower rate (90-45 kg ha-1) would probably not be recommended under these test conditions. Overall, the PNW cultivars tested outperformed the Nordic genotypes both in yield and malting quality. However, Nordal and HJA 78003 could prove useful in PNW barley breeding programs.