Inherent soil fertility as affected by Rhizobium inoculation and inorganic N application on common bean
The aim of this study was to evaluate the effect of soil fertility on the effectiveness of Rhizobium leguminosarum bv. phaseoli and N fertilizer on yield traits of common bean variety. The experiment was conducted in Babillae, Fedis, Haramaya and Hirna experimental sites. Six levels of N fertilizer (0, 20, 40, 60, 80, 100 kg N ha-1) and two levels of inoculation were factorially arranged in a randomized complete-block design with three replications. Analysis of variance indicated a significant effect of Rhizobium leguminosarum bv. phaseoli inoculation, N rates of application, location and their interaction on yield and yield components of common bean on all soil types. The highest nodule number (NN) and nodule dry weight (NDW) values were observed at 20 kg N ha-1, with the exception of Hirna location. However, the highest NN (282.00) and NDW (0.8182 g) were observed at Haramaya and Hirna sites, respectively, where the inherent soil fertility, including total N, was high. The highest plant total tissue N (PTTN) at Babillae, Fedis, Haramaya, and Hirna sites was 3.2433% at 20 kg N ha-1, 4.2000% at 100 kg N ha-1, 4.5567% at 40 kg N ha-1 and 4.8267% at 100 kg N ha-1, respectively. The highest total biomass yield at Babillae, Fedis, Haramaya and Hirna sites was 3648.1 kg ha-1 and 4740.7 kg ha-1, 6474.1 kg ha-1 and 8638.9 kg ha-1, respectively. Similarly, the highest grain yield (GY) at Babillae, Fedis, Haramaya, and Hirna sites was 2089.54, 1653.89, 2475.28 and 2441.57 kg ha-1, respectively. The highest harvest index (HI) was recorded at Babillae site.