Abstracts Geography

Effect of clays and sodium chloride on the infiltration of water in sandy soils.

by Jehangir Khan,1937- Khattak

Calcium bentonite, calcium kaolinite, and calcium illite each were mixed with salt-free sand in the ratio of 1:9 in order to make artificial sandy soils. These soils were then treated with sodium chloride so that they contained 8, 15, and 30 percent exchangeable sodium, and then subjected to artificial rain. It was observed that the runoff was increased in the following order with these soils: bentonitic soil> kaolinitic soil> illitic soil. Runoff from the bentonitic soil was increased from zero in the untreated soil to 43.0, 55.6, and 111.3 percent when the exchangeable sodium percentages were 8, 15, and 30 percent, respectively. Similarly, runoff is increased from zero to 41.6, 201.0 and 214.0 in the kaolinitic soil and from zero to 72.3, 131.5, and 143.4 in the illitic soil when the exchangeable sodium percentage is changed from untreated soil to 8, 15, and 30 percent, respectively. The experimental values for exchangeable sodium percentage were lower than the theoretical values, due to increased moisture content and erosion of soil. It was concluded from this investigation that if the artificial soils used in this work contained from 8 to 15 percent exchangeable sodium, maximum runoff would be achieved, without producing any harmful effect to the soil. The quality of the runoff water would be satisfactory for irrigation purposes.