Ben-Hur, M., Agric Res Organization, Volcani Center, PO Box 6, Bet Dagan, Israel
Faris, J., Agric Res Organization, Volcani Center, PO Box 6, Bet Dagan, Israel
Malik, M., Agric Res Organization, Volcani Center, PO Box 6, Bet Dagan, Israel
Letey, J., Agric Res Organization, Volcani Center, PO Box 6, Bet Dagan, Israel

The objectives of this rainfall simulator study were to: 1) determine the effect of drying of crusted vermiculitic soil on the subsequent crust properties and infiltration rate (IR) values, 2) determine the effect of polymers applied at low concentration in irrigation water of two qualities on the IR under consecutive water applications, and 3) determine the effectiveness of polymer applications to the soil as would be required under rainfall conditions. Except for polyacrylamide the polymer applications were relatively ineffective in subsequent sprinkler applications with plain water applied with impact energy. The beneficial effects were preserved under water application without impact energy. Spraying concentrated polymer solutions on the soil surface was not effective in preventing crust formation by following rain events except for the case when cationic polysaccharide guar with lower charge density was sprayed on in a CaCl2 solution. The results are explained on the basis of polymer adsorption and penetration into the soil surface layer and aggregates. -from Author