Department of Soil Science and Agricultural Chemistry, S.V. Agricultural College, Acharya N.G. Ranga Agricultural University, Tirupati, 517 502, Andhra Pradesh
The soils of Banaganapalle mandal in Kurnool district of Andhra Pradesh were developed from dolomite and granite-gneiss under semi-arid climate at an average elevation of 243 m above mean sea level (msl). These soils were investigated for clay mineralogy using X-ray diffraction technique and chemical analysis of clay. The clay films invariably exhibited characteristic peaks of smectite, kaolinite and illite. Semiquantification analysis of clay fractions based on relative areas under corresponding peaks indicated that pedons 1, 2, 3 and 5 were dominated by smectite followed by kaolinite, illite, feldspars and quartz while pedons 4 and 7 were dominated by kaolinite followed by smectite, illite, feldspars and quartz. The formation of smectite suggests that these soils were formed through a progressive landscape reduction process and appears to be under basic environment, impeded drainage and water logging conditions. The dominance of kaolinite may be due to their well-drained conditions. However, use and management of these soils for agricultural production require an understanding of their clay mineralogy.
Clay mineralogy, smectite, kaolinite, illite, feldspars and quartz
