In India, 49 million hectares area is affected by soil acidity, of which 25
million hectares have pH below 5.5. More than 90% area in north-eastern region
of the country is affected by soil acidity. This particular abiotic stress
limits the expansion of area under agricultural crops and their productivity in
this region. The degree of loss in crop productivity varies with varying degreee
of soil acidity. Such problematic soils have geerally been degraded naturally
and characterized by low fertility, low pH, toxicities of aluminium and
manganese and low availability of nutrients viz., phosphorus, calcium, magnesium
and potassium etc. These naturally degraded infertile acidic soils remain the
principal