Characterization, Classification and Evaluation of Soils in Semi-Arid Ecosystem of Karvetinagram Mandal of Chittoor District, Andhra Pradesh

Abstract

Seven typical pedons representing major landforms namely, plains and uplands originated from granitegneiss parent material in the semi-arid eco-system of Karvetinagaram mandal under varying land uses in Chittoor district of Andhra Pradesh, India were studied for their morphological characteristics, physical and chemical properties and soil genesis. These soils were slightly acidic to slightly alkaline (pH 6.38 to 7.85) in reaction, non-saline (0.04 to 0.52 dS m-1), shallow to very deep and had isohyperthermic temperature and ustic soil moisture regime. Texture, organic carbon (OC), cation exchange capacity (CEC) and base saturation of the soils were found to varied from sand to sandy clay loam, 0.11 to 0.63%, 9.65 to 26.84 cmol(p+)kg-1 soil and 71.7 to 90.4%, respectively. Soils were low in available nitrogen (N) (28.0 to 78.4 mg kg-1), medium to high in available phosphorus (P) (20.55 to 44.58 mg kg-1), low to high in available potassium (K) (42.8 to 194.0 mg kg-1) and sufficient in available sulphur (S) (14.3 to 63.2 mg kg-1). The DTPA-extractable zinc (Zn) (0.49 to 1.74 mg kg-1) was deficient to sufficient, whereas DTPA-extractable copper (Cu) (0.54 to 2.09 mg kg-1), manganese (Mn) (1.90 and 17.25 mg kg-1) and iron (Fe) (4.60 to 14.97 mg kg-1) were sufficient. The pedons 1, 5, and 7 were grouped under Entisols due to the absence of a subsurface diagnostic horizon and were classified as Lithic Ustorthents (pedons 1 and 7) and Typic Ustifluvents ( pedon 5). Pedons 4 and 6 were grouped under Inceptisols due to the presence of cambic (Bw) sub-surface diagnostic horizon and classified as Fluventic Haplustepts. Pedons 2 and 3 were grouped under Alfisols due to the presence of argillic (Bt) sub-surface diagnostic horizon and classified as Typic Haplustalfs. All soils of the study area fall in agricultural land under land capability sub-classes viz., IIIs, IVs and IVes. Based on major soil constraints and potentials, a suitable land use plan for Karvetinagaram mandal was suggested.