Soil Resource Assessment of Garhwal Himalayan Mountains in India.
D. Martin, S.K Mahapatra, C.B Sachdev, Tarsem Lal, Kalpana Kambli, and J.P Sharma. National Bureau of Soil Survey and Land Use Planning, ICAR, IARI campus,, PUSA, New Delhi, India
Garhwal Himalayan mountains occupy 9020 sq km area extending from 29° 25′ to 30° 52′ N latitude and 77° 56′ to 79° 15′ E longitude with relief between 350 to 6904 m MSL. The mountainous area is divided into 3 zones based on the intervening river basins and altitude, namely Greater Himalayas (GH), Lesser Himalayas (LH) and the outer Himalayan tract called Siwaliks. The Upper Himalayan tract comprising the GH and LHs are developed during the Oligocene (25-40 million yrs), mid Miocene (14 million yrs) and post Pliocene (750 thousand yrs) period. Siwaliks are originated from middle Miocene to the lower Pleistocene period. The soil resource inventory was made by interpreting the Indian remote sensing satellite data followed by soil survey. Data on image analysis and soil survey were interpreted, classified as per UDSA soil taxonomy and mapped on 1:50 000 scale. The results showed that the GHs are the upper most in the region between 4500 to 6900 m elevations and remain mostly under snow clad and devoid of settlements except in broad valleys where alpine pastures are developed. The remaining areas are occupied with very steep slopes and barren. The soils are of granitic in origin and recent. They are shallow, excessively drained, dark brown to dark yellowish brown, sandy loam to loam, rich in organic carbon with moderate to severe stoniness (Lithic Udorthents and Lithic Cryorthents). LHs are the large mountain tract between the central Himalayan thrust in the North and the main boundary thrust in South. The relief is 1500 -2700 m on hill tops and in valleys it ranges from 500 – 1200 m. This region comprises of 3 major river basins namely, Yamuna, Bhagirathi – Alakananda, which is the largest among other basins formed by the convergence of rivers Bhagirathi, Bilangana, Alakananda, Nayyer and Ganga. Ramganga- kosi is the 3rd basin in LHs. Soils in different basins vary in their morphological and physico-chemical properties being developed on different parent materials derived from different geological formations. Quartz, vermiculite, montmorillonite, kaolinite, mica and slates comprise the dominant mineral composition of these soils. Soils in the Yamuna basin are moderately deep, excessively drained, gravelly sandy loam to loam with very weak structure and horizon development (Typic Udorthents) associated with shallow, excessively drained, sandy loam soils with moderate to severe stoniness (Lithic Udorthents). Soils in the Bhagirathi – Alakananda basin are moderately deep, well drained, dark brown to dark yellowish brown, gravelly loam (Typic Udorthents) associated with deep, well drained, dark brown to brown, loam to clay loam with developed horizons and good nutrient retention capacity () and shallow, somewhat excessively drained, dark yellowish brown to brown, gravelly sandy loam to loam soils with primitive stage of profile development (Lithic Udorthents). Hill summits with moderate slopes are occupied with forests having deep, well drained, dark brown, sandy loam to loam soils with mollic epipedon (Typic Hapludolls) associated with deep, well drained, dark brown to brown, fine loamy soils (Typic Dystrudepts). They are rich in organic carbon with good fertility status. In broad valleys soils are deep, well drained, dark yellowish brown, loam to clay loam in texture (Typic Dystrudepts). Siwaliks are long and narrow chain of low hills ranging from NW to SE Himalayan tract with altitudes ranging from 750 -1200 m. Northern slopes are profusely forested and descend gently to flat floored structural valleys called dunes and the Southern slopes are steep and mostly barren. This range is divided into Dehradun, Yamuna and Ramganga tracts. Soils on hill tops of Dehradun tract are fertile and occupied with forests. Soils are moderately deep, well drained, and brown to dark brown, gravelly sandy loam to loam, slightly acidic to neutral with medium nutrient retention capacity (Typic Udorthents). Soils in the Yamuna tract are formed on lime stone and dolomite parent materials of Krol group. These soils are shallow, excessively drained, yellowish brown, sandy loam, calcareous in reaction with poor nutrient retention capacity (Lithic Udorthents). Soils in Ramganga tract are recent and developed from the fluvial material. They are deep, excessively drained, yellowish brown, sandy loam over loamy sand developed on alluvium (Typic Udifluvents). In general it is found that the soils in Himalayan Mountains are rich in organic carbon with good nutrient retention and water holding capacity. It is also found that they can be put into diverse land use and show good resilience when put under intensive agricultural land use.