Abstract
The effect of electrolyte solution (concentration and SAR) was determined on the structural behavior of two soils, Sudan Gezira clay and Houston Black clay, a Vertisol from Texas. The A11 horizon of Houston Black clay and the A11, A12, and AC horizons of the Gezira soil were compared. Disturbed samples of 2- 0.1mm standard sieve size and clod samples were equilibrated with a NaCl, CaCl mixed salt electrolyte solution varying in electrolyte concentration and SAR. Flocculation pf the disturbed samples was measured by the hydrometer method. The degree of flocculation was found to be a function of electrolyte concentration and SAR- and to a greater degree of SAR in the soils. Houston Black clay showed the highest degree of flocculation at almost all electrolyte treatments in comparison to the Gezira soil. After equilibration with the different electrolytes the hydraulic conductivity (saturated flow) of the disturbed samples was measured by the constant head method. The results indicated that hydraulic conductivity is affected by both electrolyte concentration and SAR. Comparison of the absolute magnitude of the hydraulic conductivity (cm/hr) of the soils, the following order was shown: Houston Black clay (A11)>Gezira soil (A12)>Gezira soil (AC). On the basis of rate of change or magnitude of fluctuations, the descending order was as follows: Gezira soil (AC)> Gezira soil (A12)> Gezira soil (A11)> Houston Black clay (A11). Statistical analysis indicated a significant correlation between the summation percentage of the different sized aggregates (determined by hydrometer) and the hydraulic conductivity at the 0.01 level of probability. This correlation was significant for all horizons except for the Gezira soil (A11)..
Mukhtar, Omar Mohamad Ahmed (1971). The effect of solution composition on structural behavior of two montmorillonitic soils: Gezira clay - Republic of Sudan, Africa, and Houston Black clay - a Vertisol from Texas. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -179219.