Improving faba bean (Vicia faba L.) productivity and nutrient availability through organic amendments and bio-inoculants in acidic soils stress

Abstract

This study aimed to assess the effect of coffee husk biochar application and Rhizobium inoculation on the agronomic traits and nutrient availability of various faba bean varieties. Four bean varieties (Local, Dosha, Gebelcho, and Numan), four inoculation levels (control, strains: FB-EAR-15, FB-1035, and EAL-110), and three biochar rates (0, 5, and 10 t ha⁻¹) were tested on acidic soils collected from the Gorche and Hagere Selam districts. The results revealed that the treatments applied significantly affected almost all yield-related measurements. Inoculating seeds with the EAL-110 strain and applying 10 t ha⁻¹ of biochar enhanced seed and biomass yields per plant by 7% and 8%, and 9% and 8%, respectively, compared to the control. Similarly, post-harvest soil analysis revealed a substantial change in soil physicochemical parameters following the application of 10 t ha⁻¹ of biochar compared to the control. The soil's pH, available P, exchangeable Ca, and Mg levels increased by 0.81 mg kg⁻¹, 4.6 mg kg⁻¹, 32.1%, and 46.2%, respectively. Inoculation with strain EAL-110 resulted in significant (p < 0.05) improvements in total N (16.7%) and organic carbon (3.1%). Conversely, the varieties did not significantly (p > 0.05) influence soil properties and nutrient availability. Hence, this research has identified biochar and Rhizobium inoculation as agricultural inputs with the potential to improve soil fertility, reduce soil acidity, and increase nutrient availability. Therefore, planting faba bean varieties Dosha and Numan with 10 t ha⁻¹ biochar and strain EAL-110 outperformed other treatments and is recommended for future research under farmers’ field conditions.