RESPONSE OF GARLIC (Allium sativum L.) TO VERMICOMPOST AND MINERAL NITROGEN FERTILIZER APPLICATION AT HARAMAYA, EASTERN ETHIOPIA

Garlic (Allium sativum L.) is an important vegetable crop in Ethiopia. The yield of the crop is often constrained by low and unbalanced nutrient supply in the soil. This study was undertaken to assess response of garlic variety Chelenko I to vermicompost and mineral N fertilizer application on growth and bulb yield of the crop during the 2016/2017 main rainy season. The treatment consisted of a factorial combination of four levels of vermicompost (0, 2.5, 5 and 7.5 t ha-1) and five levels of mineral N fertilizer (0, 52.5, 80, 105 and 130 kg N ha-1) were laid out in a randomized complete block design in a factorial arrangement and replicated three times. Data were collected on phenology, plant growth, yield component, and bulb yield of garlic. Results revealed early maturity (130.48 days) at nil application of fertilizers while late maturity (135.50 days) was with application of 7.5 t ha-1 of vermicompost. Significant (P < 0.05) maximum plant height (60.65 cm), leaf length (41.08 cm), bulb weight (39.17 g/bulb), clove weight (2.71 g/clove), harvest index (63.94%), marketable bulb yield (12.32 t ha-1), and total bulb yield (12.93 t ha-1) were recorded at the rate of 7.5 t ha-1 of vermicompost followed by lower dose and mineral N fertilizer while maximum average leaf width (1.28 cm), bulb length (13.57 cm), clove number (3.37 cm), and bulb dry matter (51.66%) were obtained at maximum rate of mineral N fertilizer (130 kg ha-1) followed by 7.5 t ha-1 vermicompost. On the other hand, leaf number (13.33), and neck thickness (0.88 cm), were recorded at combined application of maximum rate of vermicompost (7.5 t ha-1) and mineral N fertilizer (130 kg ha-1). The combined application of 2.5 t VC ha-1 and 52.5 kg N ha-1, 0 t VC ha-1 and 105 kg N ha-1 gave significantly optimum bulb diameter. Due to combined application of vermicompost (7.5 t ha-1) and mineral N fertilizer (130 kg ha-1) unmarketable bulb yield was reduced by 41.03% over control. From the results of this study, it can be concluded that, the highest net benefit was obtained due to the highest marketable bulb yield of garlic recorded with combined application of 7.5 t ha-1 of vermicompost and 130 kg ha-1 of mineral N fertilizers. Therefore, these rates could be considered in the production of garlic in the study area