SYNTHESIS AND PROPERTIES OF NANO LIMING MATERIALS FOR RECLAMATION OF ACID SOILS

Abstract

Occurrence of acid soils in Indian subcontinent
is highly varied in nature and it is due to wide variation
of climatic conditions. Soil acidity is caused by free
release of hydrogen, aluminium, manganese and iron
toxic concentration (Das et al., 1996). It is estimated
that of pproximately 49 m ha are acid soils with a pH
of 4 - 5.5 (Biswas and Mukherjee, 2002). In acid soils,
free release H+ and Al3+ concentrations become toxic
to plant root growth. Historically, limestone (pure
calcium carbonate) application is the most common
management practice, which is used to neutralize
the toxic concentrations of H+,Al3+,Mn, Fe and
increase the exchangeable Ca and Mg(Adams, 1984).
Pure crystalline CaCO3 is called calcite or calcitic
limestone and has a neutralising value of 100%.
Limestone is slightly soluble in pure water, however,
if the water is saturated with carbon dioxide at ordinary
temperatures, it is soluble to the extent of about one
part by weight in 1000 parts of water, forming
bicarbonates. The carbonate forms in finely divided
form may also react directly with soil colloids. The
colloids are thus charged with bases, where reaction
is accompanied by the liberation of carbon dioxide. It
also modifies the soil property and improves nutrient
availability for root growth. Usually, plants grow well
at a pH range of 6.5-7.5 due to the optimum availability
of essential nutrient sand liming is important to
maintain the pH at this range. Liming enhances the
physical (structure), chemical (essential nutrients) and
biological (microbial population) properties of soil
through its direct effect on the amelioration of soil
acidity and indirectly promotes root distribution