The application of biochar on soil acidity and other physico-chemical properties of soils in southern Ethiopia Tariku Berihun 1 *, Muluken Tadele 1 , and Firew Kebede 2 1 Department of Biology, Dilla University, P.O.Box 419 Dilla, Ethiopia 2 Department of Biology, Hawassa University, P.O.Box 05 Hawassa, Ethiopia Abstract The aim of this research was to investigate the effect of biochar amendment on soil acidity and other physico-chemical properties of soil in Southern Ethiopia using a field experiment of three treatments: (1) biochar made of corn cobs, (2) biochar made of chopped Lantana camara stem, and (3) biochar made of Eucalyptus globulus feedstock and a control, in which neither of the bio- char was used. Each treatment had three levels of 6, 12 and 18 t ha –1 . The experiment was set- up with RCBD in a factorial arrangement with three replications. In this regard, a total of 36 plots (each 2 · 2 m size) were applied with three replications to the depth of 0–15cm. From these 36 plots, composite soil samples were collected to the depth of 0–30 cm and analyzed for bulk density, total porosity, pH, soil organic carbon, total nitrogen, available phosphorus, potassium, and exchangeable acidity using standard procedures before and after biochar application. Two- way ANOVA was also used to analyze the impact of the biochars on soil acidity and other proper- ties. For the treatments that had significant effects, a mean separation was made using Least Significance Difference (LSD) test. The results showed the application of biochar significantly re- duced, soil bulk density and exchangeable acidity when compared with a control (p < 0.05). Moreover, the total soil porosity, soil pH, total nitrogen, soil organic carbon, available phospho- rus, and potassium were significantly increased in the soil. From among applied biochar treat- ments, Lantana camara applied at the level of 18 t ha –1 had a higher impact in changing soil physico-chemical properties. In general, the study suggests that the soil acidity can be reduced by applying biochar as it can amend other soil physico-chemical properties. Key words: biochar / physico-chemical properties / soil acidity / Southern Ethiopia Accepted April 01, 2017 1 Introduction Agriculture is the basis of the Ethiopian economy and accounts for up to 46% of its gross domestic product (GDP) and 63% of the national exports are from agricultural products from which 85% of the country’s labor force is engaged. Moreover, the live- lihood of about 85% of the population of Ethiopia is dependent on the agricultural sector (Taye, 2008). Nevertheless, soil acid- ity is one of the major challenges in agricultural production mainly in highland areas (Deressa et al., 2007). Several previous studies have indicated that about 40.9% of the total arable land of Ethiopia is acidic soil caused by high rainfall and temperature that result in the leaching of basic cations (Deressa et al., 2007; Taye, 2008). In addition, the acidity in the soil is increased due to the application of chemi- cal fertilizer such as nitrogen fertilizer, since nitrification pro- duces and releases high H + ions into the soil that in turn forms various reactions in the soil (Brown et al., 2008). The high concentration of Al 3+ , Fe 3+ , and H + in acid soil can reduce the soil pH < 4 and cause high P fixation, low organic matter con- tent, and diminish the activity of micro-organisms (Ferna ´ ndez and Hoeft, 2012). One of the efforts to improve soil acidity is the use of various soil amendments that are easily available and are able to survive long time in the soil (Nurhidayati and Mariati, 2014). The soil amendments widely used by farmers to increase soil pH include dolomite and calcite lime. Applica- tion of lime not only increases the pH, base saturation, ex- changeable calcium and magnesium, but also enhances the activity of soil microorganisms and improves the content of soil organic matter and soil nutrient availability (Jackson, 1967). However, limestone material is relatively expensive and challenging to afford for the subsistence farmers and the supply is limited. Due to this, farmers have recently started using biochar as alternative mechanism, as these materials are locally available and cheaper compared to limestone (Glaser et al., 2002). Biochar and its ash contents are widely known as the most ef- fective means for correcting soil acidity. The direct effect of soil amendment is a change in the soil pH. Its application usu- ally results in significant reduction of exchangeable alumi- num, allowing for a more efficient uptake of nitrogen and phosphorus (Shamshuddin et al., 2004). Biochar can be pro- duced from different plant materials including wood chips, weed species, animal manures, crop residues, grasses, and ª 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.plant-soil.com J. Plant Nutr. Soil Sci. 2017, 000, 1–8 DOI: 10.1002/jpln.201600343 1 * Correspondence: T. Berihun; e-mail: berihun.tariku@yahoo.com