AEMIRO BIRHANU
Faba bean (Vicia faba L.) is one of the major leguminous crops grown in the world. The national average faba bean yield is very low compared to its potential yield in Ethiopia because of low soil fertility. A pot experiment was conducted to evaluate the response of faba bean to rhizobium inoculation, vermicompost application and blended NPSB fertilizer rates at Debre Berhan University from December to May, 2019/2020. A factorial combination of 2 levels of rhizobium (inoculated and uninoculated), 4 levels of vermicompost (0, 3, 6 and 9 t/ha) and 3 levels of mineral blended NPSB fertilizer (0, 60, and 120 kg/ha) were laid in completely randomized design (CRD) with three replications. The soil analysis result revealed that there was a clay textural class of soil, moderate bulk density (1.43cm3 /g), moderate acidic (pH 5.6), low levels of (organic matter (1.72 %), total N (0.115%), available P(8.89mg/kg) and available S (7.2 mg/kg)); a high levels of (CEC (30.45 Cmol (+)/kg, Ex. Ca (19.72 Cmol(+)/kg soil, Ex. Mg (7.93 Cmol(+)/kg soil and Ex. K (1.21Cmol(+)/kg) and a medium levels of Ex. Na (0.68Cmol(+)/kg. Analysis of variance showed that nodulation, yield and yield components and nutrient uptake of N, P and S were significantly affected by the treatments. The highest nodule number (NN) (101.8) and nodule dry weight (NDW) (193.4 mg) were obtained at 6 t/ha application of vermicompost, however, both NN and NDW reduced by 47% as compared to 9 t/ha verimicopost application. Rhizobium inoculation increased the mean both NN and NDW by 35% over uninoculated. The highest number of nodules per plant (94.4) was recorded by the NPSB rate of 60 kg/ha while the lowest number (74) was at the control. The remaining investigated traits (pod number, straw yiled and grain yield) significantly increased by integrated use of Rhizobium inoculation, vermicompost and blended NPSB fertilizer application. The highest grain yield (80.1 g/pot), number of pod per plant (28.67) and straw yield (125.86 g/pot) were obtained from combined application of 6 t/ha vermicompost and 60 kg/ha NPSB fertilizer along with rhizobium inoculation. In this study, Rhizobium inoculation significantly improves the total N, P and S uptake by 20.4%, 15.5% and 27.1% over the control treatment, respectively. Therefore, integrated application of rhizobia inoculation, 6 t/ha vermicompost and 60 kg/ha blended NPSB fertilizer rate application is recommended to boost the productivity of faba bean in the study area. However, the experiment was conducted in green house only for one season, therefore repeating the trial on filed, at different seasons would be important to draw sound recommendation.
