Browsing by Author "SHRUTHI T. M."
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ThesisItem Open Access STUDIES ON PROPERTIES OF BLACK SOILS DERIVED FROM SCHIST, BASALT AND LIMESTONE IN NORTH-EASTERN KARNATAKA(UNIVERSITY OF AGRICULTURAL SCIENCES RAICHUR, 2013-12-30) SHRUTHI T. M.; S. L. BUDIHAL, S., G. PATIL, S. R. BALANAGOUDARThe three black soils developed on three different parent materials viz., Hira black soil derived from schist, Bidar black soil derived from basalt and Shahabad black soil derived from limestone in North-eastern Karnataka were studied horizon wise. The studies were carried out on both whole soil and their clay fractions. The texture was clay throughout the profile in both soils. The clay content increased whereas sand content decreased with depth. The structures of the three black soils were predominantly sub-angular blocky. The pH of Hira and Bidar soils was neutral but that of Shahabad soil was slightly alkaline. Dithionate extractable free iron oxides and sodium carbonate extractable free alumina and silica in the soils were determined. The per cent content of free iron oxides and boiling Sodium carbonate extractable silicon and aluminium was more in Shahabad soils compared to Hira and Bidar soils, but, the molar ratios of iron oxide to alumina was higher in Hira soil and molar ratio of silica to alumina was higher in Bidar soil than the other two soils. All three soils had high CEC, calcium and magnesium were the dominant cations on soil exchange complex. But the Bidar and Hira soils were calcium dominant but Shahabad soil was magnesium dominant. The exchangeable sodium was also higher in Shahabad soil than in the other soils studied. In the present study, Calcium Exchange Capacity, Potassium Exchange Capacity (K/EC), Specific Surface Area and coagulation threshold were determined on the separated clay fraction. There were some variations in clay charges and vermiculite content among the three black soils but there were not much variations in specific surface area and coagulation threshold of their clays.