SOIL FORMATION ALONG A TOPOSEQUENCE OVER A SCHIST LANDSCAPE
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Date
2014-07-30
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Abstract
SOIL FORMATION ALONG A TOPOSEQUENCE OVER A SCHIST LANDSCAPE
VEERESH (PG 10 AGR 2059) 2014 Dr. H.V. RUDRAMURTHY
ABSTRACT Major Advisor
Three representative diversified pedons namely red, brown and black from the geomorphic
units’ top, middle and bottom slopes, respectively in a toposequence on schist landscape from a
Gogi village of Shahapur taluk, Yadgir district, of north Karnataka belongs to north eastern dry
zone were studied for their morphological, physical and chemical features to understand their
genesis and to classify them as per USDA soil taxonomy. Red pedon was well drained as it
recorded the highest (3) moist chroma and the drainage got poor down the slope in brown and
black pedons where the moist chroma was 2 and 1 respectively. Dominant soil colour hue was
5YR in red pedon and it was 7.5 YR and 10 YR in brown and black pedons, respectively. Soil
texture got finer down the slope and it was gravelly clay loam in red pedon and clay in both
brown and black pedons. Clay skins, pressure faces and slickensides were observed in red, brown
and black pedons, respectively. CEC/clay, Feo/Fed and Sio2/Fe2o3 ratios showed increasing trend
down the slope. Genesis of these toposequence soils is attributed to the same parent roc, schist as
the chemical composition of fine sand fraction was almost same in all the pedons and to the
differences in chemical weathering due to the differences in drainage conditioned by topography.
The pedogenic processes associated with the top slope member red pedon were leaching,
decalcification, tendency of desilicification, laterization and kaolinization under well drained
condition whereas, the middle and bottom slope members brown and black pedons were formed
by the pedogenic processes calcification and silicification under poor drainage condition. Thus
Drainage, micro climate and leaching environment conditioned by the relief at the geomorphic
units’ top, middle and bottom slopes have played a key role in the genesis of these soils.
Redistribution of soluble constituents through lateral movement and particulate matter through
erosion down the slope has led to formation of these soils and is evident from both base
saturation and calcareousness of these soils. At subgroup level red, brown and black pedons were
classified as Typic Haplustalf, Vertic Haplustept and Lithic Calciustert.
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