Soil Survey and Land Use Planning Centre, Bihar Agricultural College, Sabour, Bhagalpur, Bihar, 813210.
* Present address: Depanment of Soil Science, Tirbut College of Agriculture, Dholi, Muzaffarpur, Bihar, 843121.
The acid soils developed on granite gneiss (sedentary) are characterized by yellowish red to strong brown colour, high coarse sand and clay contents, high in SiO2 and contain mottles and concretions whereas alluvial soils developed on Mahananda alluvium are pale yellow to olive in colour, high in fine sand, silt and K2O. All these soils are base unsaturated (26 to 69%) and quite low in CEC. The sedentary soils are matured as they have well differentiated horizons and the process of silicification is operating under acidic environment. However, the influence of parent materials and climate on soil genesis appears to be modified by topography. The alluvial soils are recent soils as they have no horizon differentiation. On the basis of quantitative characters, the sedentary soils have been classified as Ultic Haplustalfs, Typic Ustochrepts and Epiaquic Haplustults, whereas alluvial soils are Typic Ustochrepts, Typic Ustorthents and Typic Ustifluvents.
Granite gneiss, mottles, concretions, silicious, base unsaturated
