ABSTRACT
Acidity is a major degradative factor of soils and covers an extensive area of both tropical and temperate regions (Fig. 1). Acid soils occupy nearly 30% (3.95 bha) of the arable land area (1) in both tropical and temperate belts. Depending on the degree of weathering and soil acidity, the world acid soils are classified into eight groups (entisols, inceptisols, andisols, spodosols, alfisols, ultisols, oxisols, and histosols). Among them, oxisols, ultisols, and alfisols represent the ma jority of the acid soils in the tropical region (1). The cold and temperate acid soils are mainly dominated by spodosols, alfisols, inceptisols, and histosols, and the tropical belt is dominated by ultisols and oxisols.
