Soil Survey & Land Use Planning Centre, Bihar Agricultural College, Sabour, Bhagalpur, Bihar, 813210.
* Present address: Department of Soil Science, Tirhut College of Agriculture, Dholi, Muzaffarpur, Bihar, 843111.
Genetically, the clay minerals in the Tal land soils representing Rasaibigha, Khanpur and Aurahi series developed on alluvium derived from rocks like granite-gneiss, mica-schist, quartzite, etc. seem to be geogenic and also pedogenic. The formation of smectite appears to be under basic environment, impeded drainage and waterlogged condition for a limited period. Mica is found to be derived from the micaceous parent material and feldspar. A major portion of kaolinite has been inherited from the parent materials. Some of the orthoclase feldspars appear to have weathered to kaolinite.
Granite-gneiss, mica-schist, quartzite, clay minerals, basic environment, tal land soils
