Evaluation of Biochar Produced from Cocoa Pod Husks for Soil Amendment in Ondo State Cocoa Farms

Cocoa pod husks constitute a major biomass residue of the cocoa processing industry in Ondo State, South West Nigeria, where Nigeria's largest cocoa production belt is located. This study evaluates biochar produced from cocoa pod husks as a soil amendment for improving the physicochemical properties and productivity of cocoa farm soils. Pod husks were pyrolysed at 350 and 550 degrees Celsius in a batch reactor under limited oxygen conditions. Produced biochars were characterised for yield, pH, electrical conductivity, carbon content, BET surface area, cation exchange capacity, and nutrient content. Pot experiments were conducted using acidic cocoa farm soils from Idanre Local Government Area amended with 2.5%, 5%, and 10% biochar by weight, with an unamended control. Soil pH, water holding capacity, available phosphorus, exchangeable cations, and microbial biomass carbon were measured after 8 weeks of incubation. Biochar produced at 550 degrees Celsius exhibited higher carbon content (72.4%), BET surface area (186 m2/g), and pH (9.3) compared to the 350 degrees Celsius product. Amendment with 5% high-temperature biochar raised soil pH from 4.8 to 6.4, increased water holding capacity by 38%, and doubled available phosphorus. Microbial biomass carbon increased by 63% relative to the control, indicating improved biological fertility. The study supports cocoa pod husk biochar as a sustainable soil conditioner for restoring degraded cocoa farmlands in Ondo State. Keywords: biochar, cocoa pod husk, soil amendment, soil pH, Ondo State