Effect of Combined Application of Organic and Mineral Nitrogen and Phosphorus Fertilizer on Soil Physico-chemical Properties and Grain Yield of Food Barley (Hordeum vulgare L.) in Kaffa Zone, South-western Ethiopia

Abstract

Low soil fertility is one of the major factors limiting the yield of barley in Kaffa Zone, south-western Ethiopia. The problem is more severe in the Zone due to soil erosion and nutrient leaching caused by heavy and continuous rainfall. Thus, field  experiment was conducted to assess the effect of combined organic and mineral  nitrogen (N) and phosphorus (P) on selected soil physico-chemical properties and  on grain yield of food barley in Ghimbo and Adiyo districts, south-western Ethiopia. Fourteen treatments comprising two organic fertilizer rates, i.e. 2.5 and 5 t ha −1 of Farm Yard Manure (FYM) and Vermicomost (VC) combined with three levels of  mineral NP (25, 50 and 75% of recommended rates of NP), 100% recommended  rate of inorganic NP (23 kg N ha -1 and 46 kg P 2 O 5 ha -1 ) and no fertilizer  application (control) in randomized complete block design on clay soil in Ghimbo and clay loam soil in Adiyo with three replications. Results indicated that the application of FYM in combination with different levels of recommended rates of inorganic N and P significantly improved most of the soil physico-chemical properties and  significantly increased the grain yield of food barley over the application of 100%  mineral NP alone and the control. The application of 5 t FYM ha −1 in combination  with 75% recommended rates of inorganic N and P (17.25 kg N ha −1 and 34.5 kg  P 2 O 5 ha −1 ) was found to be superior and increased soil organic carbon content by 36 and 44.6%, available P by 70.5 and 78.2%, available K by 42.5 and 26.3%, and increased yield of barley by 76.8 and 83.5% in Adiyo and Ghimbo, respectively, over the application of 100% recommended rate of inorganic N and P only. Therefore, it can be concluded and recommended that the application of 5 t FYM ha −1 in combination with 75% of the recommended rates of inorganic N and P  (17.25 kg N ha −1 and 34.5 kg P 2 O 5 ha −1 ) can improve soil fertility and can  increase yield of food barley in the study area. Keywords: Farmyard manure, Nitrogen, Phosphorous, Vermicompost, Ethiopia.