Soils carry both the positive and negative charges simultaneously but quantitatively charges are variable in space and time. Samples from the A and B horizons of a normal (Ustalfic Haplargids) and a saline-sodic (Typic Halorthids) soils were collected. Positive and negative charges were determined by saturating the soils with 1 N KCl and adjusting pH to 6, 8 and 10. The soils were then extracted with 0.2 and 0.5 N MgSO4.7H20 or Na2SO4 solutions. Negative charges statistically increased with an increase in the adjusted pH of both the soils. The increasing concentration of extracting solutions increased the negative charge, increase being more with MgSO4.7H2O than that with Na2SO4. Almost similar was the response of positive charge of soils to pH, concentration and nature of electrolytes. Negative charge was significantly higher in the A than in the B horizon. However, charge was higher in the Hafizabad than that in the Khurrianwala soil series. Similar was the response of positive charges to pH, and concentration and nature of electrolytes in both the soils.
Electrolyte, pH, pH-dependent charge, permanent charge, zero point of charge
