Physico-chemical properties and its relationship with water holding capacity of cultivated soils along altitudinal gradient in Sikkim

A study was carried out to evaluate the physical and chemical properties of soils and its relationship with water holding capacity along altitudinal gradient for cultivated soils of East 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 (6.7) to highly acidic (4.2) in reaction. The organic carbon content varied from 1.23 to 3.35 per cent with mean value 2.29 per cent. The bulk density, particle density, porosity, volume expansion and water in air dry soils ranged from 1.08 to 1.53 gm/cc, 2.15 to 2.76 gm/cc, 36.25 to 57.72 per cent, 2.94 to 11.9 per cent and 0.68 to 4.32 per cent, respectively. The water holding capacity (WHC) ranged from 35 to 72.85 per cent with a mean value 53.43 per cent. The results revealed that 75 per cent of the soil samples have medium to high WHC while only 25 per cent are of low category. The percentage of WHC decreases with increase in altitude. A significant positive relationship was observed between WHC and organic carbon, clay and volume expansion, while, a negative relationship was found with bulk density, particle density and sand, silt content.