Layer-charge characteristics of smectite in thai vertisols
Chittamart, Natthapol (Kasetsart University. Department of Soil Science)
Suddhiprakarn, Anchalee (Kasetsart University. Department of Soil Science)
Kheoruenromne, Irb (Kasetsart University. Department of Soil Science)
Gilkes, Robert J. (University of Western Australia. School of Earth and Environment)

Date:	2010
Abstract:	The fertility of soils with respect to K and NH is often difficult to measure, but is essential for achieving effective agronomic practices. This problem is especially important in the Vertisols of Thailand. The purpose of the study reported here was to characterize the composition and layer-charge behavior of Thai Vertisols in order to understand better their K and NH fertility. Topsoil and subsoil clay of 12 representative highly smectitic Vertisols from Thailand were studied. Interlayer swelling of smectite with alkylammonium cations, cation exchange capacity (CEC), and chemical composition were determined. These data and the re-expansion on glycerol treatment of Li-saturated, heated smectite demonstrated that high-charge, Fe-rich beidellite is the major clay mineral in these soils. The beidellite has a heterogeneous layer-charge distribution as measured by the alkylammonium method, with mean values ranging from 0. 43 to 0. 62 charges per half unit cell. The layer charge determined by CEC and structural formula methods for some almost pure smectites is smaller (0. 32-0. 54) and greater (0. 46-0. 69), respectively, than determined by the alkylammonium method. The structural formulae of beidellite confirm that the layer charge originates mostly in the tetrahedral sheet.
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Layer-Charge Characterization ; High-charge Fe-rich Beidellite ; Smectite Properties ; Vertisols ; Tropical Soils ; Thailand
Published in:	Clays and Clay Minerals, Vol. 58, Núm. 2 (2010) , p. 247-262, ISSN 1552-8367

DOI: 10.1346/CCMN.2010.0580209

16 p, 992.3 KB  UAB restricted access

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