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Chemistry of pedogenesis in Indo‐Gangetic alluvial plains
Author(s) -
TOMAR K. P.
Publication year - 1987
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1987.tb02275.x
Subject(s) - udic moisture regime , pedogenesis , silt , weathering , alluvium , geology , clay minerals , soil water , mineralogy , geochemistry , alluvial plain , soil horizon , leaching (pedology) , soil science , geomorphology , loam , paleontology
SUMMARY Five soil pedons–two aquic and two udic Haplustalfs and one petrocalcic Natrustalf–from the Indo‐Gangetic alluvial plain of Western Uttar Pradesh were investigated to evaluate the pedogenetic processes. Sand/silt ratios indicate that parent material discontinuities are insignificant. Higher K content and lower SiO 2 /R 2 O 3 ratios of the non‐clay fractions in Bt, rather than in the A, horizons suggest maximum weathering at or near the surface. An almost linear relationship between decrease in molar SiO 2 /R 2 O 3 and % increase in clay to about 100cm depth in all the pedons, presence of clay argillans in Bt horizons (where % clay, fine/coarse clay ratio and bulk density values are greatest), all indicate that the development of argillic horizons in these soils was due, at least partly, to lessivage of clay. Fe in clay fractions decreases with depth whilst Al increases, but in the fine earth both increase steadily with depth. This, together with crystalline iron concretions in the lower Bt horizons, suggests that in Haplustalfs these horizons are gaining clay by neoformation/ reorganization of illuviated constituents, especially A1 2 O 3 .