Effect of Potassium Fertilizer and Lime Application on Yield and Quality of Soybean (Glycine max L. (merrill) in Acidic Soil of Gobu Sayo District, Western Oromia, Ethiopia

The experiment was to evaluate the influence of potassium fertilizer and liming the soil on yield, yield related traits and quality of soybean (Glycine max L. (merrill) on acidic soil in Gobu Sayo district, western Ethiopia. Soil acidity problem is one of the bottlenecks to improve crop production in high rainfall areas of Ethiopia in general and in western parts of the country in particular. A field experiment was carried out during the 2016 main cropping season at three locations (Gishe, Laften and Ago). Five levels of potassium fertilizer (0, 20, 40, 60, and 80 kg ha-1) and two levels of lime (0 and 4.6 t ha-1) were applied as two factors. Fifty (50) kg ha-1 P2O5 with seed inoculation by biological organism (legume fix strain) was also used as standard check. The eleven treatment combinations were arranged in a randomized complete block design (RCBD) with three replications. KCL was used as K2O source and applied in two splits at planting time and at vegetative growth stage. The full dose of lime was broadcasted a month before planting on those plots which received lime. The analysis of variance indicated that there were highly significant interactions (P<0.001) between potassium and lime applications for most measured plant variables, especially on yield and quality parameters except number of seeds per pod. The highest soybean grain yield (3642 kg ha-1) was obtained at Gishe site when 60 kgha-1 K2O and 4.6 ton ha-1lime was applied while the lowest yield (1014 kgha-1) was recorded at Ago site for the control treatment. As quality of seed, application of K2O significantly increased protein content of soybean seeds but lime interaction with K2O and K2O alone had negative effect in reducing oil content of soybean seeds. Hence, K2O at a rate of 60 kgha-1 with 4.6 tha-1 lime were recommended to increase grain yield of soybean in acidic soils of the study areas. However, the response of soybean having different maturity groups and inoculation of different biological strains should further be tested in combination with liming and potassium fertilizer to come up with conclusive recommendations. Keywords: Acidic Soil; Lime; Potassium; Quality; Soybean; Yield DOI: 10.7176/FSQM/90-01 Publication date:September 30th 201