Effects of seeding and nitrogen fertilizer rates on malting barley yield and quality in highland tropical environment

Abstract

The expansion of brewing industries in Ethiopia has been inducing a growing demand for the supply of malt with optimum kernel protein content. However, the supply has been constrained by the unavailability of sufficient volumes of acceptable quality of malting barley grain to meet the ever-increasing demand. In this regard, field experiments were conducted in the southeastern Ethiopian highlands to examine the combined effects of five seeding rates (100, 125, 150, 175 and 200 kg ha^-1) and four nitrogen (N) fertilizer levels (0, 18, 36 and 54 kg ha^-1) on the yield, yield components and protein concentration of malting barley. The experiment was laid out in a randomised complete block design with three replications. Increasing seeding rate from 100 to 125 and 150 kg ha^-1 improved the grain yields by 173 (6%) and 329 kg ha^-1 (10%), and economic profitability by US$6.58 and US$4.15 respectively, for each US$1.00 investment on seed. Similarly, application of 18, 36 and 54 kg N ha^-1 increased the grain yields by 309 (10%), 490 (17%) and 639 kg ha^-1 (22%), and economic benefits by US$8.14, US$4.44 and US$2.78 respectively, for each US$1.00 investment on N fertilizer, when compared to the control. These achievements were without detrimental effect to the kernel protein concentration of malting barley. The production of malting barley with improved yield, optimum kernel protein concentrations and enhanced economic benefit was attained through seeding at a rate of 125 – 150 kg ha^-1 along with 18 – 54 kg N ha^-1 on suitable soil types in the southeastern highlands of Ethiopia and other areas with similar agro-ecologies. Thus, to improve the likelihood of acceptance of malting barley by malting industries, growers are recommended to select low-protein containing varieties and decide application of N fertilization based on soil test results.