Physical Properties of the Mountain Soils of Cross River State, Nigeria
The mountain soils of Cross River State, Oban hills and Obudu mountains have the following properties. The sand contents in Oban hills ranged from 34 to 82% while in Obudu plateau from 40 to 78 %. The silt contents of the soils in both Oban hills and Obudu plateau fluctuated with depth. At Oban hills the range was between 6 and 36 %, and 10 and 26 % at Obudu plateau. Clay contents at Oban hills ranged from 6 to 42 % while it ranged from 10 to 44 % at Obudu plateau. The bulk density values for both study sites increased with soil depth. The range of values at Oban hills top soils was 0.67 to 1.87 g/cm3, with the mean of 1.38 g/cm3 while values for subsoil horizon ranged from 1.64 to 2.33 g/cm3 with mean of 2.02 g/cm3.The range of bulk density values from the Obudu mountains was from 0.74 to 2.16 g/cm3. The soil surface values ranged from 0.74 to 1.75 g/cm3, with the mean of 1.2 g/cm. The total porosity values of Oban hills for top soil horizons ranged from 29.43 to 74.72%, with the mean of 47.93%. The subsurface horizon values ranged from 12.08 to 40.38%, with a mean of 22.54%. The surface soil horizon values at the Obudu mountains ranged between 33.96 and 70.08%, giving a mean of 50.63% while the subsurface values ranged from 19.62 to 55.47%, with the mean of 29.08%. Oban hills and Obudu mountain soils are rated good soils based on their total porosity values. The hydraulic conductivity values in the Oban hills ranged from 0.74 to 103.87 cm/hr. At the surface horizons, the conductivity values ranged from 7.56 to 103.87 cm/hr with the mean of 34.42 cm/hr. The subsurface horizon values ranged from 0.74 to 42.83 cm/hr, with the mean of 10.13 cm/hr. Hydraulic conductivity values at the Obudu mountains ranged from 0.05 to 78.99 cm/hr. The surface values ranged between 0.52 and 78.99 cm/hr, with the mean of 31.16 cm/hr. The subsurface horizon values range was from 0.05 to 42.13 cm/hr with the mean of 14.94 cm/hr. The conductivity values were high.
Keywords: Texture, hydraulic conductivity, bulk density, porosity.