Biochar as a substitute for inorganic fertilizer: Effects on soil chemical properties and maize growth in Ghana

Owing to the benefits of biochar in soil sustainability, this study considered the effect of applying rice husk biochar as a substitute for inorganic fertilizer on soil properties and maize growth in Ghana. Six treatments (comprising of five rice husk biochar rates and one rate of NPK inorganic fertilizer as control) with four replicates in a pot experiment and "Obaatanpa" maize variety were used for the study. Results showed that the incorporation of biochar increased soil pH, organic carbon and effective cation exchange capacity for the various treatments which were higher than NPK treatment. Generally, 50 t/ha biochar applied at the time of planting recorded the lowest soil chemical properties which resulted in reduced maize germination count and yield while 50 t/ha biochar applied 2 weeks before planting improved soil chemical properties. Biochar increased all soil chemical properties analyzed more than NPK except for available phosphorus and potassium, which are key nutrients for maize growth. The maize yield in the biochar treatments was significantly lower (by 300%) than the NPK treatment, suggesting that biochar application in the short term, although could increase soil chemical properties, does not translate into essential nutrients available for improving maize yield. Therefore, quantity and incubation time for rice husk biochar before planting has a significant impact on soil nutrient and yield of maize. Future studies should consider the application of biochar at a longer period before planting and in combination with inorganic fertilizer as a top dressing and residual biochar for maize production.