CLAY MINERALOGY OF ENTISOL AND INCEPTISOL SOIL SERIES OF MPKV FARM R AHURI
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Date
30-12-94
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MAHATMA PHULE KRISHI VIDYAPEETH RAHURI, 413 722 DIST- AHMEDNAGAR. Maharashtra State (India)
Abstract
Important and widespread Entisols and Inceptisols soil series of Central Campus Farm, Mahatma Phule Krishi Vidyapeeth, Rahuri were assessed for their fine an.d coarse clay mineralogy, chemical mposition, molar ratios, morphological characters and physical and chemical properties. The data on important morphological, physical and chemical characteristics of soils used confirmed the Entisol and Inceptisol nature and were derived from basalt/ basaltic alluvium and slightly conditioned by topography. As They were categorised„very shallow to very deep, gravelly loam to silty clay loatn, brown to dark brown in colour, alkaline and calcareous in nature, low in organic matter which decreased with depth, having no salinity problem and were found' low, moderate and high in available N, P and K contents, respectively. The CEC and base saturation of Inceptisols were found higher than Entisols with Ca + + as the dominant exchange base. The X-ray diffractograms/ chemical composition and molar ratios revealed the ominance of smectite in fine clays with small proportion of kaolinite. The Greene-Kelly test established the predominance of beideliite rather than montmorillonite as low proportion of montmorillonite was observed in fine clays of Entisols and Inceptisols and smectite was found to be of beidellite-montmorillonite series. The fine clays showed higher intensity of weathering than coarse clays. The XRD of coarse clay indicated the presence of smectite, kaolinite, quartz, illite, feldspars, chlorite and vermiculite. The structural formulae computed from the total elemental analysis of fine clays( <0.2Ai) of Entisols and Inceptisols did not show much variation. The derived formulae are : Entisols: 0<7l(Si7>3£)Al0#70) (Al2-39Pe1-02Mg0#87) 02Q(OH)4 and Inceptisols: X0.67(Si7.35Al0.65> (Al2 .41Fei .07^0 .92> °20(OH)4 These formulae also show beidellite-montmorillonite series with more charge deficiency at tetrahedral layers than octahedral layers* Thus, topography changed the morphological* physical and chemical characteristics of these soils but had negligible effect on clay mineral assemblage.