Department of Soil Science and Agricultural Chemistry, Rajasthan College of Agriculture, Udaipur, Rajasthan, 313.
1 National Bureau of Soil Survey and Land Use Planning (ICAR), Regional Centre, Udaipur, 313001.
Distribution, transformation, movement and accumulation of carbonate and its impact on physical and chemical characteristics of soils were studied, to understand their genesis and classification. CaCO3 ranged from 31.8 to 69.6 per cent, out of which maximum was in sand (37.6 to 68.3%), and decreased in silt (16.9 to 28.4%) and clay (17.0 to 34.6%). Carbonate In clay was the function of ESP and weathering index (Al2O3/Fe2O3) while that in sand and silt it was related to the latter alone. Water soluble sodium, calcium and bicarbonate jointly moved downward and precipitated in the vicinity of nodule, gravel rich horizons. Overall gain! loss of clay and carbonate of clay size were influenced by ESP. An accumulation of carbonate resulted in reduction of porosity, water holding capacity, sodium hydrolysis and increased bulk density. Soils were classified under sodic Ustic Haplocalcid, subgroup of Aridisol soil order. An amendment to soil taxonomy is suggested.
Clay size carbonate, ESP, soil moisture regime, soil properties
