Abstract:
This study investigates the potential of locally sourced carrier materials for formulating
rhizobia inoculants to enhance legume productivity and promote sustainable agriculture
in southern Ethiopia. Inoculating legume seeds with effective rhizobia strains has been
proven to significantly enhance nitrogen fixation, plant growth, and agricultural
productivity. However, effective carrier materials are critical for maintaining rhizobia
viability and functionality, yet suitable options are scarce in Ethiopia. Thus, we evaluated
five locally available materials; coal, charcoal, silkworm feces (SWF), compost and
water hyacinth biochar (WHBC), for their suitability as carriers. The physiochemical
properties of the carrier materials, their storage conditions (4°C and room temperature),
and effectiveness in promoting nodulation at intervales of 60 days for five times were
evaluated. Physicochemical analysis revealed that WHBC and SWF exhibiting superior
water holding capacity (647% and 230.46%, respectively), high nutrient and mineral
contents, sustaining rhizobia counts above the commercial threshold (>108 CFU/g) for
300 days at both temperatures. Greenhouse experiments demonstrated that inoculants
formulated with these carriers significantly enhanced nodulation and shoot biomass,
exceeding the coal-based formulation used as standard in Ethiopia. The study advocated
for their adoption to improve soil fertility, reduce fertilizer dependency, and enhance food
security in Ethiopia.
