Seasonal Variations in Soil Conditions, Its Classification and Mapping of Dry Sub Tropical Region of Uthal, District Lasbela

Abstract

The study on soil classification and seasonal variation was carried out during 2011-12 in Tehsil Uthal, District Lasbella (Balochistan). The water and soil samples were collected and subjected to determine for various physico-chemical properties and accordingly the results were formulated and compared with standard values. In winter soil EC in Zone 1, Zone 2, Zone 3 and Zone 4 area was 2.218, 1.99, 2.43 and 1.22 dS m^-1,pH value 8.1, 8.3, 8.3 and 7.8, HCO₃^- 2.0125, 1.725, 1.675 and 2.5875 meq L^-1, Na²⁺ 13, 12, 11.4125 and 14meq L^-1 ,Ca²⁺ 7, 6, 6 and 7meq L^-1 while the TDS in soil samples were 1571, 1638, 1902 and 837, respectively. In summer soil EC in Zone 1, Zone 2, Zone 3 and Zone 4area zones was 2.27, 2.04, 2.66 and 1.29 dS cm^-1, pH value 8.7, 8.4, 8.4 and 8.0, HCO₃^-1.7375, 1.675, 1.5375 and 1.85meq L^-1, Na²⁺ 13, 13, 12 and 16meq L^-1,Ca²⁺6, 6, 6 and 7meq L^-1 while the TDS in soil samples were 1605, 1713, 1001 and 952, respectively. Average value of EC_e of 2.04 dSm^-1.  The EC_e values ranged 1.08 to 3 dSm^-1. The average values of EC_e at the given depth verify that marginal salinity was present in the soil. This may be due to the leaching of salts to the deeper layers. The average value of SAR is 9.18. The SAR ranged from 6.8 to 12.2. The ratios are less than 13 which show that concentration of Na⁺ ions to that of Ca⁺² and Mg⁺² is low. The average value of SAR is 9.18. The SAR ranged from 6.8 to 12.2. The ratios are less than 13 which show that concentration of Na⁺ ions to that of Ca⁺² and Mg⁺² is low. This shows improvement in soil.

Keywords: Soil, Electrical Conductivity, SAR, Summer, Winter, Zones, Mapping