Physico-chemical properties and water holding capacity of cultivated soils along altitudinal gradient in South Sikkim, India

An investigation was carried out to study the physical and chemical properties of soils and its relationship with water holding capacity along altitudinal gradient for cultivated soils of South Sikkim. The physiography of the study area was mainly hilly terrain with closely spaced contour on steep sloppy lands. The soil texture ranged from sandy loam to clay with slightly acidic (6.6) to highly acidic (4.2) in reaction. The organic carbon content varied from 1.22 to 3.45 per cent with a mean value of 2.31 per cent. The bulk density, particle density, porosity, volume expansion and water in air dry soils ranged from 1.08 to 1.54 gm/cc, 2.05 to 2.77 gm/cc, 42.44 to 61.73 per cent, 2.95 to 11.9 per cent and 0.68 to 4.32 per cent, respectively. The water holding capacity (WHC) ranged from 33 to 73.86 per cent with a mean value of 54.18 per cent. The results revealed that 80 per cent of the soil samples have medium to high WHC while only 20 per cent are of low category. A significant positive relationship was observed between WHC and organic carbon, clay and porosity, while, a negative relationship was found with pH and bulk density with sand and silt content.