Polymer effects on erosion under laboratory rainfall simulator conditions.
Ben Hur M. | Letey J. | Shainberg I.
Soil erosion by water is a serious problem in several parts of the world. Incorporation of polymers into water applied to soil by a rainfall simulator can improve infiltration rates. This study was conducted to determine the effects of nonionic, anionic, and two charge densities of cationic derivatized guar products on erosion and infiltration rates. The polymers were mixed with distilled water at concentrations from 0 to 20 g m-3 and applied through a rainfall simulator in the laboratory. Untreated distilled water was applied to an Arlington sandy loam soil (Haplic Durixeralf) with the soil surface both unprotected and protected by a fiberglass sheet placed 0.5 cm above the soil surface. All polymer treatments were applied to the unprotected soil surface. Distilled water drop impact greatly reduced infiltration rate and increased erosion, compared with no impact. The anionic and nonionic polymers did not significantly affect erosion or infiltration rate, compared with distilled water. The cationic polymers significantly increased infiltration rate and erosion, compared with distilled water. The higher charge cationic polymer produced significantly higher values than the lower charge polymer at the same concentration. The distilled-water treatment with impact caused severe aggregate disruption and dispersion, producing a layer of fine material at the surface that decreased infiltration rate. Apparently, the very-fine particulates became imbedded in the soil matrix, which made them less susceptible to lateral transfer with flowing water. The flocculating action of the cationic polymer created larger particulates, which had very little effect in reducing infiltration rate but were more susceptible to erosion. Under the conditions of the experiment, particulates between 0.05 and 0.25 mm were most susceptible to transport by a thin sheet of flowing water.
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