Lime, an alkali that can reduce soil acidity. Its chemical formula is CaO which reacts with water and decomposes to calcium hydroxide (Ca(OH)2). When Ca(OH)2 gets dissolved in water, it liberates Ca2+ and OH- ions. The presence of excess OH- ions results in an increase in pH of the soil, i.e. from acidic to alkaline. Therefore, lime is used to reduce the acidity of the soil.