Characterisation and Classification of Cotton growing soils in Amaravathi area of Guntur District, Andhra Pradesh
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Date
2009
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
Abstract
Eight representative soil profiles of black and associated soils from
Amaravathi area of Guntur district, Andhra Pradesh were selected and
described for their site and morphological features. Horizon wise soil samples
were collected from each profile and subjected to laboratory analysis to study
the physical, physico-chemical and chemical properties. The clay samples from
the control section of six profiles were analysed for clay minerals. The soils
were classified up to family level as per USDA Soil Taxonomy (Soil Survey
Staff, 1998). The soil survey data were interpreted for Land Capability
Classification as per the guidelines given by Sehgal (1996). Suitability of the
soils for growing cotton crop was evaluated using FAO criteria (FAO, 1976).
The study area falls in semi-arid climate with distinct wet and dry
seasons. All the profiles were derived from granitic-gneiss parent material.
Topography of the study area varied from plain lands to gently sloping lands.
The colour of the soils varied from very dark grayish brown to dark gray
(1, 2, 3 and 6), brown to dark yellowish brown (4, 5 and 7) and brown to dark
brown (8).
The texture of the study area varied from sandy loam to clay and
structure from granular to sub-angular blocky at surface and sub-angular
blocky to angular blocky in sub surface layers among different profiles. The
bulk density values of the soils were low at surface compared to subsurface
layers. Pore space, water holding capacity, volume expansion and sticky point
values varied according to clay content.
The soils were slightly alkaline to moderately alkaline in reaction. EC
values of the soils were low except in profile 6. Relatively high CEC values
were observed in profiles 1, 2, 3, 5 and 6 compared to profiles 4, 7 and 8,
where the CEC was less than 30 cmol (p+) kg-1 soil. Calcium was the dominant
cation on the exchange complex, followed by magnesium, sodium and
potassium in all the profiles. Elemental composition data revealed that silica
and sesquioxides were the dominant fractions followed by calcium and
magnesium oxides.
The soils were low in N, medium to high in P and K. Among
micronutrients copper and manganese were sufficient, while zinc and iron were
deficient in these soils.
X-RD data revealed that the clay fraction of all these soil profiles had
dominance of smectite, with small quantities of illite and kaolinite.
The soils were classified based on morphological, physical, physicochemical,
mineralogical and meteorological data as
Profile 1 & 2 : Very fine, smectitic, isohyperthermic, Udic Haplustert
Profile 3 : Fine, smectitic, isohyperthermic, Udic Haplustert
Profile 4 : Loamy, smectitic, isohyperthermic,Vertic Haplustept
Profile 5 : Fine, smectitic, isohyperthermic, Typic Haplustert
Profile 6 : Very fine, smectitic, isohyperthermic, Typic Haplustert
Profile 7 and 8 : Fine loamy, smectitic, isohyperthermic, Typic Haplustept
Land evaluation for land capability revealed that, the profiles 1, 2 and 3
were classed under sub class IIIwf. Profiles 4 and 5 were grouped under IIIsf,
while profiles 6, 7 and 8 were classified under IIsw, IIIs and IVsf, respectively.
The soils represented by profiles 1, 2, 3, 4 and 5 are marginally suitable
(S3) due to severe limitations of fertility and moderate limitation of drainage
and depth of the profiles, while profiles 7 and 8 are marginally suitable for
cotton due to severe limitations of coarse fragments , depth and organic carbon
content. Profile 6 is moderately suitable (S2) due to moderate limitation of
organic carbon content of the soils.
Description
Keywords
Characterisation, Classification, Cotton, growing, soils, Amaravathi, area, Guntur District, Andhra Pradesh