Morphological, chemical and mineralogical characterization of developing soils and their management in the western Siwalik Himalayas

Abstract

The western Siwalik Himalayas of India experienced the last climate shift 3500 years ago and the soils have been marked by rigorous human activities for a few centuries. An attempt was made to investigate the interactions between soil-forming factors and processes in soil development in relation to land forms and climate change. The hallmark of the soils is the considerable heterogeneity in solum and regolith thickness, horizon boundaries, structural development in surface soils, pH, electrical conductivity and soil mineralogy, irrespective of landscape form and position. A remarkable feature of the soils is the development of deep argillic horizons, or B horizons, in certain landscape positions. The minerals identified were quartz, micas and feldspars in the sand and silt fractions. Illite, kaolinite, vermiculite, smectite and chlorite were present in the clay fractions. Soils under forest vegetation and those recently brought under cultivation belong to Typic Hapludalfs. Soils cultivated over centuries, however, failed to qualify as Alfisols and were classified as Typic/Dystric Eutrudepts. The eroded barren soils were similarly classified as Typic Udorthents. All the soils were low to medium in available nitrogen and phosphorus. The use of nitrogen and phosphorus fertilizer is therefore needed to ameliorate nutrient deficiency and boost crop production. Because of the presence of appreciable amounts of potassium-bearing minerals, soils are likely to be non-responsive to potassium application. The soils of the Dala series (Typic Hapludalfs) are located on moderate hill slopes and thus soil erosion is less severe than for the Mansu series (Typic Udorthent). In the Chamror and Dhar series (Typic/Dystric Eutrudepts) soil erosion is not a serious problem because of terracing and the finer texture of the soils. Crops can thus be grown on profile-stored moisture during dry periods and limited grazing may be permitted.