Studies on genesis, characterization and classification of soils in central and Eastern parts of Prakasam district in Andhra Pradesh

Abstract

Seven typical pedons representing major land forms in central and eastrern parts of Prakasam district viz., plains and uplands developed from granite-gneiss, sand- stone and alluvium parent material under varying land use were studied for their mor- phological characteristics, physical and physico-chemical properties, soil genesis and nutrient status. Soils were shallow to very deep, slightly acidic to slightly alkaline (pH 6.02 to 8.45) in reaction, non-saline and had iso-hyperthermic temperature and ustic soil moisture regimes. Texture, organic carbon, CEC and base saturation were ranged from sand to clay in surface and sub-surface, 0.12 to 0.68 per cent, 3.48 to 48.74 cmol (p + ) kg - 1 and 73.44 to 91.52 per cent, respectively. Soils were low in available nitrogen, medium in available phosphorus, low to high in available potassium and high in available sul- phur. However, the soils were deficient in DTPA-extractable Zn and sufficient in Fe (except in pedon 6, surface horizon of pedon 4 and sub-surface horizons of pedon 2), Cu and Mn. Pedons 2 and 6 were grouped under Entisols due to absence of sub-surface diagnostic horizon and were classified as Typic Ustipsamments and Typic Ustorthents, respectively whereas pedons 1, 4, 5 and 7 were placed under Inceptisols due to presence of cambic (Bw) sub-surface diagnostic horizon and classified as Typic Haplustepts (pedons 1, 4 and 5) and Lithic Haplustepts (pedon 7). Due to the presence of vertic features like slickensies, pressure faces, cracks and presence of more than 30 % clay in all the horizons, the pedon 3 was grouped under Vertisols and classified as Typic Haplusterts. The soils were also evaluated for commonly grown crops of the area.