EFFECTS OF TYPES AND RATES OF BLENDED FERTILIZERS ON SELECTED CHEMICAL SOIL PROPERTIES AND YIELD OF COMMON BEAN (Phaseolus Vulgaris L.) IN DEBUB ARI DISTRICT, SOUTHERN ETHIOPIA

Production and productivity of common bean is decreased mainly by soil fertility depletion, inappropriate rate of poor nutrients availability and application without soil test, and inefficient crop response. Crop specific fertilizer recommendation is necessary for sustainable crop production. Accordingly, a field experiment was conducted during the main rainy season of 2019 to evaluate the effects of types and rates of blended fertilizers on selected soil chemical properties and yield and yield components of common bean at Jinka Agricultural Research Center in Debub Ari district, Southern Ethiopia. The experiment consisted of 11 treatments viz. control (without any fertilizer), RNP (64N and 46P2O5), 100 kg NPS, 150 kg NPS, 200 kg NPS, 100 kg NPSB, 150 kg NPSB, 200 kg NPSB, 100 kg NPSZnB, 150 kg NPSZnB, and 200 kg NPSZnB ha-1 blended fertilizers. Muriate of Potash containing 0-0-60 was applied at planting in all treatments except the control plot. The experiment was laid out in Randomized Complete Block Design with three replications. Soil samples were collected from the experimental field (0-20 cm depth) before planting and after harvest to determine selected soil properties. After harvesting, the crop was partitioned into straw and grain for the determinations of N, P, and K concentrations, uptakes, and calculation of N and P fertilizer recoveries and use efficiencies. The experimental soil is sandy loam in texture, slightly acidic in reaction, very low in organic carbon, low in total nitrogen, low in available P, low in available K, medium in available B, and low in available Zn, medium extractable S, and moderate in CEC. The analysis of variance showed that the application of blended fertilizers were significantly (p < 0.05) increased most yield and yield parameters of the common bean compared to the control plots. The maximum grain yield (3477.0 kg ha-1 ) was obtained from the application of 200 kg ha-1 of NPSB followed by the treatment of 200 kg NPSZnB, 150 kg NPSB, 150 kg NPSZnB and 200 kg NPS ha-1 while the minimum (1857.9 kg ha-1 ) was obtained from the control. The result indicated that nutrient content and uptake by common bean increased when the blended fertilizer rates increased. The application of 150 kg NPSB ha-1 had maximum and acceptable Marginal rate of return (MRR %) and net benefit. Therefore, this type and rate of blended fertilizer (150 kg NPSB ha-1 ) can tentatively be recommended since it produced a high marginal rate of return, high net benefit, and relatively low total cost of production, for common bean production in the study area.