Biochar and Inorganic Fertilizers for Acidic Soil Management: Improving Soil Properties and Potato Productivity in Ethiopia

This case study investigates the combined application of coffee husk biochar and inorganic fertilizers to improve soil properties and potato productivity on acidic soils in Southwestern Ethiopia. Soil acidity and low fertility due to nutrient leaching coupled with limited inorganic fertilizer use severely constrain crop yields in the region. The research tested four levels of biochar (0, 2.5, 5, and 7.5 t ha⁻¹) with four rates of inorganic nitrogen and phosphorus fertilizers (0, 75%, 100%, and 125% of recommended rates) in a randomized complete block design. Results demonstrated that combining 7.5 t ha⁻¹ biochar with recommended NP fertilizer (165 kg N and 60 kg P ha⁻¹) significantly improved soil pH (from 4.87 to 6.47), organic matter content (71% increase), cation exchange capacity (52.58% increase), total nitrogen (39.28% increase), and available phosphorus (133.2% increase) compared to using inorganic fertilizer alone. This soil improvement corresponded with a 28.99% increase in potato tuber yield. The findings highlight biochar's potential as a sustainable soil amendment for ameliorating acidic soils through multiple beneficial mechanisms beyond simple pH adjustment, offering a promising approach for sustainable soil fertility management in tropical agricultural systems.