Vermicompost Application as Affected by Rhizobium Inoculation on Nodulation and Yield of Faba Bean (Vicia Faba L.)

The effect of vermicompost on the effectiveness of Rhizobium inoculation on nodulation, yield and yield traits of fava bean at Haramaya, eastern Ethiopia, was investigated. Ten treatments were made by afactorial combination of five levels of vermicompost (0, 2, 4, 6 and 8 ton ha-1) and two levels of Rhizobium inoculation (inoculated anduninoculated. The treatments were laid out in arandomized complete block design with three replications. Analysis of variance revealed that Rhizobium inoculation, vermicompost application, cropping season and their interactions significantly (P <0.05) affected all investigated traits of faba bean. Over years, the highest mean nodule number (NN) (298.00) and nodule dry weight (NDW) (0.7598 g) were recorded at 4 ton ha-1. Rhizobiuminoculation increased the mean NN and NDW by 6 and 11%over uninoculated, respectively. The remaining investigated traits remarkably increased with increasing levels of vermicompost application and Rhizobium inoculation. Regardless of inoculation, the mean grain yield over years was increased with increasing vermicompost application rates. The highestmean grain yield (4822.1 kg ha-1) was found at 8 ton ha-1 vermicompost application. Total mean P accumulation increased from 0.12894 to 0.17110% when the vermicompost rates were increased from unfertilized at 8 ton ha-1. However, inoculation and vermicompost application did not affect significantly (P >0.5) mean total plant N concentration. Hence, integrated application of Rhizobiumand8 ton ha-1vermicompost is needed to boost the productivity of faba bean in the study site.