Water used for irrigation in many semiarid regions of the world contains high levels of salinity and/or sodicity which affect hydraulic conductivity. Polymers mixed with the irrigation water may affect hydraulic conductivity. The hydraulic conductivity of a Haplic Durixeralfs soil classified as Arlington sandy loam was measured in disturbed laboratory columns using waters of various electrolyte concentrations, sodium adsorption ratios, and with or without a polymer. Cationic polysaccharide, guar derivative (CP-14), and very low negative charge polyacrylamide (2J) polymers were investigated. After passing several pore volumes of water through the soil, the soil was removed from the column, dried, sieved, and repacked into the columns. The hydraulic conductivity was then measured using city of Riverside, CA tap water. The greatest increase in hydraulic conductivity with CP-14 compared to the control occurred with SAR equal to 5 and at the two highest electrolyte concentrations. The 2J polymer was most effective in increasing hydraulic conductivity when it was added to the high electrolyte solution. During the second run with tap water, the hydraulic conductivity for no polymer and CP-14 treatments were similar to each other and less than the 2J treatment. The polyacrylamide apparently promoted aggregate stability to the soil when it is dried, whereas the guar did not. This behavior may be caused by the high molecular weight of the polyacrylamide.
(C) Williams & Wilkins 1991. All Rights Reserved.