Genesis, characterization and classification of soils from selected parts of Prakasam district in Andhra Pradesh, India

Seven typical pedons from Chimakurthi, Marrichetlapalem, Iapavaluru, Rudravaram, Taragudipadu, Chellapalem and Mainampadu villages representing major land forms in the selected parts of Prakasam district of Andhra Pradesh viz., uplands and plains, developed from granite-gneiss parent material under varying land use were selected for the present study. These pedons were studied in detail for their morphological characteristics, soil genesis, physical and physico-chemical properties and nutrient status. Soils in the area were moderately deep to very deep, slightly alkaline to alkali (pH 7.24 to 10.35) in reaction, non-saline. They had ustic soil moisture regime and iso-hyperthermic temperature regime. Texture, organic carbon, CEC and base saturation in the profiles ranged from loamy sand to clay, 0.18 to 0.70 per cent, 8.65 to 51.48 cmol (p+) kg-1 and 62.87 to 90.92 per cent, respectively. These soils were found to be low in available nitrogen, low to high in available phosphorus, medium to high in available potassium and sufficient in available sulphur (except in lower layers of pedon 2). They were found to be deficient in DTPA-extractable Zn (except in the surface horizons of pedons 3 and 4). However, they were sufficient in DTPA-extractable Fe (except in the Bw1 horizon of pedon 1), Cu (except in the 3A3 horizon of pedon 7) and Mn. The pedons 2 and 7 were grouped under Entisols due to absence of sub-surface diagnostic horizon and were classified as Typic Ustorthents at sub-group level; pedons 1, 3, 5 and 6 were placed under Inceptisols due to presence of cambic (BW) sub-surface diagnostic horizon and classified as Typic Haplustepts at sub-group level. The pedon 4 was grouped under Vertisols due to the presence of vertic features like slickensides, pressure faces, cracks and presence of more than 30 % clay in all the horizons and was classified as Typic Haplusterts at sub-group level. Location specific recommendations were made based on the physical, physico-chemical characteristics and fertility status of these soils for better and sustainable crop production besides conserving and improving the soil health.