State the process of Formation of Acid Soils
The soil acidity is mainly caused by hydrogen and aluminium ions, depending upon the degree of existing soil acidity. At very low pH (<5.0) aluminium is soluble and hydrolyses to Al(OH)2+, the H+ ions released are responsible for acidity. At a pH range of about 5.0 and 6.5, aluminium, in presence of OH- ions gets converted to Al(OH)+ 2ions which on further hydrolysis form aluminium hydroxide and H + ions, again adding to the soil acidity.