Biochar-based organic fertilizer for sustainable acidic soil amendment and crop production in acrisols of northwestern Ethiopia

Soil acidity and nutrient depletion are major constraints to agricultural productivity in the northwestern Ethiopian highlands. Biochar has emerged as a promising amendment for improving acidic soils. Its effectiveness may be enhanced when combined with compost, farmyard manure, and inorganic fertilizers. However, limited field-based evidence exists regarding the combined effects of these amendments on soil physicochemical properties and teff productivity in the acidic Acrisols of Ethiopia. Therefore, this study evaluated the effects of 29 nutrient management treatments comprising biochar (B), compost (C), FYM (M), inorganic fertilizer (F), and their combinations applied at rates of 5, 10, and 15 t ha −1 on soil physicochemical properties and teff productivity in Fagta Lokoma District, northwestern Ethiopia. A randomized complete block design with three replications was employed, and treatment effects were analyzed using analysis of variance (ANOVA). Nutrient management treatments significantly ( P < 0.05) improved soil physical and chemical properties compared with the control. Bulk density decreased from 1.21 to 0.99 g cm −3 , while soil moisture content increased to 62% under biochar applied at 15 t ha −1 . Soil pH increased from 4.61 to 5.42, indicating substantial amelioration of soil acidity. Soil organic carbon, total nitrogen, available phosphorus, and cation exchange capacity were also significantly enhanced, particularly under integrated treatments. The combined application of biochar, compost, FYM, and inorganic fertilizer (BCMF) at 15 t ha −1 produced the highest grain yield (3.32 t ha −1 ) and aboveground biomass yield (16.60 t ha −1 ), compared with 0.51 t ha −1 grain yield in the control. These findings demonstrate that integrated nutrient management can effectively improve soil fertility and teff productivity in acidic Acrisols. Among the tested treatments, BCMF at 15 t ha −1 showed the greatest agronomic performance; however, further long-term agronomic, economic, and environmental evaluations are required before large-scale recommendation and adoption.