Use of Biochar to Improve Selected Soil Chemical Properties, Carbon Storage and Maize Yield in an Ultisol in Abakaliki Ebonyi State, Nigeria

Biochar, short form for bio-charcoal is plant derived carbon obtained through pyrolysis of plant various origins. It is mostly composed of carbon and comes in the form of small black and highly porous fragments. It may also contain organic molecules. Biochar has been the focus of increasing interest as it claimed to be a way to almost permanently lock atmospheric carbon of unused plant residue (that would otherwise limit CO2 during natural decomposition), which is transported through pyrolysis into stable black carbon and various gas products. This carbon is then ploughed into the soil, where it is permanently stored, while almost enhancing the soil productivity. The biochar physicochemical properties can cause changes in the soil nutrient and C availability, and provide physical protection to microorganisms against predators and desiccation; this may alter the microbial diversity and taxonomy of the soil (Lehman et al., 2011). Biochar addition to the soil have been found to stimulate mycorrhizal infection (Satio, 1999; Ishii and Kadoya, 1994) and influence phosphorus solubility in forest soil (Gundaie and Deluca, 2007) which may be responsible for observe increase in phosphorous uptake. The mediation of nutrient turnover by biochar has significant implication for organic agricultural system where biochar may increase the stabilization or organic nutrient source (Glaser et al., 2001) and reduce nutrient leaching losses (Lehmann et al., 2003). Addition of biochar to soil provides a modest contribution of nutrient depending, in part upon the nature of the feed stock and upon the temperature under which the material is found (Bridle and Pritchard, 2004; Gundale and Deluca, 2006). Biochar boost the cation exchange capacity (CEC) of soils, reduces aluminum toxicity in some soils, reduce nutrient leaching especially nitrate and also restructure soil to improve soil physical properties. However, biochar is more important as soil conditioner and driver of nutrient (Berglund et al., 2004).The total carbon content of biochar varies considerably depending on feedstock and may range from 400gkg1 up to 900gkg1 (Antal and Gronli 2003; Chan and Xu, 2009; Gaskin, et al., 2010). The highest carbon content is obtained from hard wood feed stocks pyrolyzed at high temperatures. Biochar is first and foremost characterized by its high organic carbon content which mainly comprises conjugated aromatic compounds for six carbon atoms linked together in rings. Beside the large carbon component, the elemental composition of biochar consist of hydrogen and oxygen, as well as different minerals for example Nitrogen, Phosphorus, suphur depending on the feedstock (Lehmann, et al, 2009). Researches on biochar as soil amendment are very few in the study area. Therefore, the main objective of this study is to determine the effect of biochar on soil chemical properties, carbon storage and maize performance in an Ultisol in Abakaliki, Southeastern Nigeria.