SOIL FERTILITY STATUSAND EFFECT OF NITROGEN RATES ON GRAIN QUALITY AND NITROGEN USE EFFICIENCY OF MALT BARLEY (Hordeum vulgare L.) VARIETIES AT WELMERA DISTRICT, CENTRAL HIGHLANDS OF ETHIOPIA

Poor soil fertility is the major constraint affecting the productivity of malt barley in the highlands of Ethiopia. Malt barley responds well to growth limiting nutrients in the soil, especially nitrogen. A field experiment was conducted at Welmera District during 2017 cropping season to determine soil fertility status and the optimum nitrogen application rates for malt barley production without affecting grain quality. The treatments were a factorial combination of five N rates (0, 23, 46, 69 and 92 kg ha-1) with three malt barley varieties (EBON174/03, Traveler and HB-1963). The experiment was laid out in a randomized complete block design with three replications. Soil analytical results indicate that soil texture was clay dominated, strong to moderately acidic (pH 5.06 to 5.93), low to medium OM (1.48 to 2.41%) on research site and medium (2.95to 4.24%) on farmer’s field, low TN (0.11 to 0.21%) on research site and very low (0.10 to 0.17%) on farmer’s field. Available P ranged from low to medium (3.97 to 8.29 mg kg-1) at research site and low to high (3.94 to 10.78 mg kg-1) on farmer’s field. Exchangeable Ca2+ was very low (0.55 to 0.86 cmol kg-1) on research site and (0.42 to 0.58 cmol kg-1) on farmer’s field, low to high Mg2+ (0.28 to 3.6 cmol kg-1) on farmer’s field and high (2.78 to 5.01 cmol kg-1) at research site. The CEC was varied from medium to high (29.26 to 32.76. cmol kg-1) at research site and medium to high (24.08 to 27.4) on farmer’s field. Grain and biomass yield were significantly (P < 0.01) influenced by interaction effects of N rates and varieties. The highest grain yield (5921kg ha-1) was obtained from EBON174/03 variety at a rate of 92 kg N ha-1onHoleta research site. The highest grain protein (13.4%) and nitrogen content (2.3%) were recorded from Ebon174/03 variety at a rate of 92 kg N ha-1. The highest AUE (72 kg kg-1) and PUE (167 kg kg-1) from HB_1963 variety but for ARE (181%) was obtained from Traveller variety at 23 kg N ha-1. Net benefit of 41234.1 ETB ha-1 from Traveller variety at 92 kg N ha-1 with marginal rate of return 1.10 per ETB invested on farm. Therefore, application of 92 kg N/ha rates for Traveller variety production was economically feasible with acceptable grain quality in Welmera areas.