Agronomic Performances of Faba Bean (Vicia faba L.) Varieties to Rhizobial Inoculation, Biochar and Lime Applications Under Acidic Soil Conditions in Ethiopia

Abstract

Soil acidity influences nutrient availability and plant growth performances in Ethiopian highlands. Sustainable agronomic practices like bio-organic amendments are getting attention to address such problems. This study was, therefore, conducted to evaluate the effects of various bio-organic amendments on the grain yield and yield components of faba bean varieties under field conditions. Treatments were arranged in a split-split plot within a complete block design: two levels of Rhizobium inoculation as the main plot, three varieties of faba beans as subplots, and four levels of coffee husk biochar-lime amendments as sub-subplots in three replications. The results revealed that Rhizobium inoculation increased the nodule count, biomass, and grain yields by 39.7%, 21.9%, and 23.1%, respectively. Application of the recommended biochar rate was found to increase the nodule count by 49.4%, and its combination with lime was shown to enhance nodule formation and overall yield of faba beans. Notably, applying 10 t/ha of biochar resulted in grain and biomass yield increments of 69.2% and 77.5%, respectively. Furthermore, a remarkable grain and biomass yield improvement was observed with the combined application of Rhizobium inoculant and biochar. The cost benefit analysis also showed a net profit of 361,637.3 Ethiopian Birr/ha when 10 t/ha of biochar was applied with a marginal return rate of 1468.8%, translated into an additional income of 14.68 Ethiopian Birr per unit of investment. The present finding showed that the combined use of bio-organic supplements can be taken as a good option for sustainable faba bean production on acid soils with viable economic returns.