Characterization and classification of soils in semi-arid region of chennur mandal in Kadapa District, Andhra Pradesh

Eight typical pedons representing major land forms in semi-arid ecosystem of Chennur mandal viz., plains and uplands developed from limestone and weathered-gneiss complex parent material under varying land use were studied for their morphological characteristics, physical and physicochemical properties to support soil genesis and nutrient status. Soils were shallow to very deep, slightly alkaline to strongly alkaline (pH 7.4 to 8.5) in reaction and non-saline. The soils were sandy clay loam to clay and clay content ranged from 21.32 to 39.92 per cent. The organic carbon in soils ranged from 1.6 to 8.8 g kg⁻¹ and cation exchange capacity from 25.65 to 53.92 cmol(p⁺)kg⁻¹ soil, respectively. Soils were low to medium in available nitrogen, medium to high in available phosphorus, low to high in available potassium and high in available sulphur. In general, soils were deficient in DTPA-extractable Fe and sufficient in DTPA-Zn, Cu and Mn. Pedons 1, 2 and 6 were grouped as Lithic Ustorthents, Typic Ustorthents and Typic Ustifluvents, respectively; whereas pedons 3, 4, 5, 7 and 8 were placed under Inceptisols due to presence of cambic (Bw) sub-surface diagnostic horizon and classified as Typic Haplustepts and Vertic Haplustepts, at sub-group level. The soils of the study area fall under agricultural land with land capability classes ranging from II to IV. On the basis of major soil constraints, suitable land use plan for Chennur mandal was suggested for their sustainable management.