SOIL FERTILITY STATUS AND EFFECTIVENESS OF NP, NPS AND NPSB FERTILIZERS FOR WHEAT (Triticum aesticum L.) PRODUCTION AT GULTI BOLA IN AMEYA DISTRICT, SOUTHWEST SHOA, ETHIOPIA

Ensuring food security for the ever-increasing world population has direct relation with management of lands resources that are vital for crop production. Inadequate information on soil fertility status and poor management practices are among the main constraints to crop production in Ethiopia. Wheat is one of the most important cereal crops in Ethiopia. Yield of this crop is low mainly due to low soil fertility. In Ethiopia, Urea and DAP (di-ammonium phosphate) are the only fertilizers that have been in use with blanket recommendation as soil fertility management inputs for the past four decades. To overcome the constraints associated with soil fertility to crop production, fertilizers containing N, P, K, S, B and Zn in blended form were recommended for ameliorating site specific nutrient deficiencies and thereby increasing crop productivity. The experiment was conducted during 2019/20 cropping season at Ameya district, southwest shoa with the objectives to assess the status of soil fertility, to evaluate the effectiveness of DAP, NPS and NPSB fertilizers in wheat production and to map soil fertility status of Gulti Bola Kebele. Composite soil samples were collected at 20 cm depth for assessment of soil fertility. The 4 treatments used for the field experiment were; control, recommended NP (100 kg/ha), NPS (100kg/ha) and NPSB (100kg/ha).The recommended Urea fertilizer was equally applied to all treatments except control. The experiment was conducted in randomize complete block design with six replications. Clay, clay loam and loam are the dominant textural class of the soil. The soil pH value ranged from 5.82 to 6.60, which implies moderately acidic and neutral in reaction. Total nitrogen and Organic carbon varied 0.11- 0.17 and 1.28- 2.4% classified low and very low respectively. Available phosphorus and sulfur were varied from 11.44 - 29.39 and 8.41 - 10.21 mg/kg which were medium to high and low and very low respectively. The relative abundance of basic cations in the exchangeable complex of soil was dominated by calcium (Ca) followed by potassium (K), magnesium (Mg) and sodium (Na) with the mean values of 9.37, 5.15, 2.27 and 0.15 cmolc kg-1, respectively. The mean value of cation exchangeable capacity (CEC) were 23.62 cmolc kg-1. Iron, Copper and Zinc level was high to very high while Boron deficiency accounted for the study area. The result of soil nutrient analysis showed that N, P, S, B, (in localized area of Ameya district) were found to be deficient for optimum crop growth. Based on this value, addition of those nutrients as blended (NPS and NPSB) and gradual buildup of soil organic matter will be increase yield. Yield and yield components of wheat was significantly affected by the treatments except 1000-grain weight and spike length. The highest above ground dry biomass yield (13647.2 kg/ha), highest grain yield (5364.7 kg/ha) and straw yield (8283.2 kg/ha) was recorded from application of NPSB blended fertilizer. The application of blended fertilizer NPSB increased the above ground biomass, and grain yield by 73.13 and 72.56% respectively as compared to the control plot. The highest net benefit (69307.51 ETB ha-1) with (MRR %) 1966.5 was obtained with application of blended fertilizer NPSB. Therefore, application of blended fertilizer NPSB can be recommended for higher yield particularly in the study area and it is also economically feasible