Nutrient Characteristics of Biochar Derived from Cocoa Husk, Rice Straw and Corn Cob and Their Effects on Maize Yield in Ghana

Abstract

The Inadequate soil fertility remains a major constraint to maize production in Ghana and large areas of sub-Saharan Africa, especially in regions having weathered Ultisols with low organic matter and nutrient-holding capacity. The present study investigated the impact of locally produced agricultural residue-derived biochar on maize yield under field conditions in Ghana. Biochar was obtained from cocoa pod husk, rice straw and corn cob by pyrolysis at 500°C for 45 minutes in the total absence of oxygen and chemically characterised. The field study was carried out at Kwadaso, Ghana, in a split-split plot design with three replications over the principal and minor crop seasons. Treatment included biochar type and application rate (2.5 t ha⁻¹, 5 t ha⁻¹) in comparison with fertilizer. The pH of all the biochars was strongly alkaline (pH 10.3–10.4). Soil amendment Biochars made of rice straw showed the highest organic C (41.0%) and available P (343.6 mg kg⁻¹), whereas those derived from cocoa husk had the highest exchangeable base cations. Application of biochar significantly enhanced the growth and yield of maize as compared to the control. At 5 t ha⁻¹, application led to a 32.9% and 58% increase in grain and cob yields, respectively. Response in yield was not dramatically different among the biochar types. These findings confirm that indigenous biochar feedstocks increase the productivity of maize and the sustainable management of soil fertility in Ghana.