Agronomic efficiency of N of common bean (Phaseolus vulgaris L.) in some representative soils of Eastern Ethiopia

Nitrogen is the major plant nutrient that limits common bean production throughout sub-Saharan Africa. Four experimental trials were conducted at four areas namely Babillae, Fedis, Haramaya, and Hirna experimental sites to determine if various inherent soil fertility status and soil total N might affect the N use efficiency of common bean var. Dursitu. Six levels of N application and two inoculation treatments were factorially combined and laid out in randomized complete block design with three replications. The agronomic efficiency of N (AE-N) by common bean obtained from different locations displayed significant difference at p ≤ 0.05. The highest AE-N was obtained from Babillae site, while the lowest from Hirna site. In general, overall AE-N declined with increase in rates of N application. Slight increase of AE-N was observed in Babillae and Hirna sites when 20 kg N ha−1 was applied. Haramaya and Hirna sites had the highest of all investigated growth parameters, except 100 seeds weight and harvest index. The regression analysis indicated strong and negative association (R2 = 0.498 and R2 = 0.390 at p ≤ 0.05) between AE-N and N rates of application in Babillae site followed by Fedis site, respectively. A stronger and significant association (R2 = 0.276, p ≤ 0.05) of AE-N and grain yield was observed only in Hirna site. In general, this study indicated the remarkable effect of soil inherent fertility and soil total N content on N use efficiency of common bean in the study sites.