Infiltration in a calcareous sandy soil as affected by water-soluble polymers

Deep percolation loss of irrigation water is one of the main limitations in most agricultural soils of Saudi Arabia. Some synthetic polymers proved to be effective in mitigating this constraint. The present study was undertak en to investigate the changes in cumulative infiltration (D) and advance of the wetting front (Z) under ponded irrigation water using water-soluble po lymers. Three different polyacryalmide (PAM) polymers, one nonionic (2J), a nd two anionic (21J and 40J) were used in this study at concentrations of 0 , 10, 20, 30, 40, and 50 mg L- to determine D and Z in a calcareous sandy s oil (Typic Torripsamments). The results showed that for the three polymers at a given time, both D and Z decreased with increase in concentration. The decrease in D was slight, whereas that in Z was pronounced. The time requi red for Z to reach a given value was in the order 40J > 21J > 2J. This orde r is mainly attributed to the viscosity of the polymer solutions. The resul ts also showed that the polymers at concentrations from 250 to 1000 mg L- d isplaped non-Newtonian poly. The viscosity of 2J, 21J, and 40J at 250 mg L- were 7.78, 10.56, and 9.90 mPa.s at a shear rate of 245 s(-1). Since these water-soluble polymers affect the wetting front mainly through their effec ts on viscosity, the potential of using them for soil erosion control is go od, but their use for increasing water availability in the soil is not good .