American Journal of Water Science and Engineering 2019; 5(4): 155-161 http://www.sciencepublishinggroup.com/j/ajwse doi: 10.11648/j.ajwse.20190504.13 ISSN: 2575-1867 (Print); ISSN: 2575-1875 (Online) Responses of Soybean (Glycine max L.) Varieties to NPS Fertilizer Rates at Bako, Western Ethiopia Dame Oljirra, Tasisa Temesgen * School of Natural Resource Management and Environmental Sciences, Haramaya University, Dire Dawa, Ethiopia Email address: * Corresponding author To cite this article: Dame Oljirra, Tasisa Temesgen. Responses of Soybean (Glycine max L.) Varieties to NPS Fertilizer Rates at Bako, Western Ethiopia. American Journal of Water Science and Engineering. Special Issue: Soil, irrigation and Water Management. Vol. 5, No. 4, 2019, pp. 155-161. doi: 10.11648/j.ajwse.20190504.13 Received: September 27, 2019; Accepted: November 6, 2019; Published: November 27, 2019 Abstract: Soybean (Glycine max. L) is among the most important legume crops produced in western Ethiopia. However, declining soil fertility and poor soil fertility management practices decrease yields. A field experiment was conducted in Bako Agricultural Research center during 2018 main cropping season to investigate the effect of NPS rates on yield and yield components of soybean varieties and to identify economically feasible rates of blended NPS rate that increase the productivity. Dhidhessa, Ethio-yugoslavia and Wello of soybean varieties and five rates of NPS (0, 50,100,150 and 200 kg ha -1 ). The experiment was laid out in arrangement in RCBD with three replications. The highest hundred seed weight (16.9g) was recorded from Ethio-yugoslavia and the lowest (15g) from Wello. Significant effect was exhibited on days to 50% flower, above ground biomass yield and seed yield due to main effects of NPS rate. The highest (55.78) and the lowest (53.78) numbers of days to flowering were recorded due to application of 200 kg NPS ha -1 and 0 kg NPS ha -1 , respectively. The tallest (81.63cm) and the shortest (65.60 cm) plants were recorded under 200 kg NPS ha -1 and 0 kg NPS ha -1 , respectively. The highest (8718 kg ha -1 ) above ground dry mass was obtained at the highest rate of 200 kg NPS ha -1 and the lowest (6910 kg ha -1 ) was due to 0 kg NPS ha -1 . The highest (2763 kgha -1 ) seed yield was recorded from the application of 100 kgha -1 NPS rate and the lowest (1935kgha -1 ) seed yield was recorded from nil application of NPS fertilizer rate. The best combination with high grain yield and economic benefit is 100kgha -1 NPS fertilizer rate with Didhessa Variety. The major measured parameters contributing for grain yield were above ground biomass, number of pod per plant and no of primary branch per plant. This experiment generally confirmed as 100kgha -1 NPS for soybean was appropriate. This trial was conducted at strong acid soil, these it is expected as the plants might not have access to use the applied fertilizer and if it was conducted with lime application the responses might be changed. Thus, it can be concluded that combined application of 100 kg ha -1 of blended NPS with Dhidhessa variety could be used at similar agro ecology. However, since the study was conducted for one season at one location, it has to be repeated over seasons and locations to make a conclusive recommendation. Keywords: Blended Fertilizer, Nitrogen, Phosphorus, Sulfur, Yield Component 1. Introduction Soybean was first introduced to Ethiopia in 1950’s because of its nutritional value, multipurpose use and wider adaptability in different cropping systems [1]. It is a crop that can play major role as protein source for resource poor farmers of Ethiopia who cannot afford animal products. Besides, it can also be used as oil crop, animal feed, poultry meal, for soil fertility improvement and more importantly as source of foreign exchange earnings for the country [2]. In Ethiopia, soybean has adapted to diverse ecological niches and provided wider yield range [1]. Soybean was produced on about 38,166.04 ha of land and 81241.833 tons produced in 2015/16 main cropping season with the productivity of 2.1 t ha -1 ; which is low as compared to world average of 2.6 t ha -1 [3]. This low yield may be attributed to a combination of several production constraints among which low soil fertility, periodic moisture stress,