Sustainable soil health and agricultural productivity with biochar-based indigenous organic fertilizers in acidic soils: insights from Northwestern Highlands of Ethiopia

Depletion of soil fertility in tropical regions is a pressing concern contributing to lower crop yields. This study aimed to evaluate the effects of biochar and co-composted biochar on acidic soil and the growth performance of teff (Eragrotis teff (Zucc.)) in the sub-tropical highlands of Ethiopia. Co-composted biochar was produced by mixing Acacia decurrens biochar with chicken litter and cow dung manure at different ratios of 100:0:0, 25:75:0, 15:85:0, and 25:0:75. Treatment impact on soil properties and crop yields were evaluated with applications of 0, 5, 10, and 20 t ha–1 in field trials. The study shows interaction effects of biochar-based amendments significantly (P < 0.001) improved soil bulk density (g/cm3), moisture content (%), pH, total nitrogen (%), total organic carbon (%), available phosphorus (mg/kg), cation exchange capacity (cmol ( +)/kg)) and teff yield. The application of 20 t ha–1 sole biochar significantly improved soil acidity by 0.99 units. Soil treated with 20 t ha–1 of BCLL and BCM resulted in notable increases in soil pH, ranging from 0.12 to 0.83 units for BCLL and 0.15 to 0.81 units for BCM. Soil treated with 20 t ha–1 BCLL showed a significant increase in tef grain yield, with improvements of 315%, 48%, 48%, and 84% compared to the control, compost, inorganic fertilizer, and sole biochar application, respectively. In conclusion, the application of 20 t ha–1 BCLL has significantly improved soil properties and crop yield. This emphasizes the need to expand the intervention to assist farmers facing similar soil fertility challenges.