Characterization and Classification of Soils of A Microwatershed on Basalt Parent Rock in Northern Transition Zone of Karnataka
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Date
2011
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UAS, Dharwad
Abstract
A study was undertaken to characterize and classify soils of a microwatershed
in northern transition zone of Karnataka to assess land capability and soil-site
suitability for irrigation and crops with special objective to study fertility constraints
by GIS techniques.
The microwatershed has topographic variations with slope ranging from 1 to
15%. Ten pedons representing the microwatershed were characterized, classified and
assessed for land capability and suitability for crops. Soils were shallow to deep, dark
reddish brown to very dark greyish brown, granular to sub-angular blocky in
structure, excessive to poorly drained, slightly acidic to slightly alkaline (pH, 6.22-
8.42), non-saline (EC, 0.20-1.03 dS m-1), low to high in organic carbon (1.3 -11.5 g
kg-1) and low to moderate in CEC (5.12-66.31 cmol (p+) kg-1) with wide textural
variations (extremely gravelly sand to clay) with depth. Argillic horizon and
slickensides were prevalent in pedons of red and black soils, respectively. According
to Soil Taxonomy, out of ten pedons, three were Lithic Ustorthents, Typic
Haplustepts and Typic Haplustalfs while others were Typic Haplusterts at sub-group
level. Five soil series were identified and mapped into ten mapping units which were
evaluated for land capability, irrigability and soil-site suitability for crops. Land
capability subclasses in the study area were III, IV and VII with limitations of texture,
drainage, fertility and topography. Land irrigability classes were currently unsuitable
to marginally suitable with limitations of topography and texture. No land was highly
suitable for crops. Majority of the crops were moderately to marginally suitable and
few were currently and potentially unsuitable.
Assessment of soil fertility status revealed that, major area was high in organic
carbon and available nitrogen. Available P ranged from low to medium in status. The
microwatershed was rich in available potassium except hill-tops. Entire area was high
in Cu, Fe and Mn but low in available S and Zn.