The inorganic N requirement, nodulation and yield of common bean (Phaseolus vulgaris L.) as influenced by inherent soil fertility of eastern Ethiopia

ABSTRACT

Though mineral N application impaired nodulation initiation and function, it improves the productivity of common bean. The effect of inorganic application on common bean productivity, however, is dependent on the availability of plant nutrients including nitrogen (N) in the soils. Therefore, multilocation field experiments were conducted at Babillae, Fedis, Haramaya, and Hirna to evaluate the effect of inherent soil fertility status on responsiveness of common bean to different rates of N fertilizer application and its effect on nodulation, yield, and yield components of common bean. The treatments were six levels of N fertilizer (0, 20, 40, 60, 80, and 100 kg N ha⁻¹) laid out in randomized completed block design with three replications. The result revealed that 20 kg N ha⁻¹ application significantly improved the nodule number (NN) and nodule dry weight (NDW) except Hirna site, in which reduction of NN and NDW was observed. Although the remaining investigated yield and yield components were significantly improved due to N fertilizer in all study sites, 40 kg N ha⁻¹ application resulted in significantly increased GY of common bean at Fedis, Haramaya, and Hirna site, while 60 kg N ha⁻¹ at Babillae site. The highest total biomass yield (7011.6 kg ha⁻¹) and GY (2475.28 kg ha⁻¹) of common bean were recorded at Hirna and Haramaya sites, respectively, indicating the importance of better fertile soil for good common bean production. Hence, it can be concluded that the effect of inorganic N on common bean was irrespective of soil fertility rather the total amount of N in soil would affect the need of different rate of inorganic N.

KEYWORDS:

• common bean
• eastern Ethiopia
• inherent soil fertility
• nitrogen application