Submitted to: International Erosion Control Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 12, 1995
Publication Date: N/A
Interpretive Summary: Polymers are being reevaluated for use on erodible lands to help stabilize soil surface aggregates, reduce crusting, and increase plant emergence. The material is most often applied by ground spray rigs to obtain either uniform full coverage, or band or strip application, preferably at high concentrations. The paper describes the changes in the spray pattern and flow rate from a typical fan spray nozzle as the concentration of a high molecular weight polyacrylamide (PAM) increases from zero to 600 parts per million. The results will help to design spray equipment to apply PAM on irrigated soils or construction sites for erosion control or plant establishment.
Technical Abstract: When applied to the soil surface, polyacrylamide (PAM) may stabilize soil surface aggregates, inhibit crust formation and reduce soil erosion during surface or sprinkler irrigation, or rainfall. Thus, PAM maintains high water infiltration rates, and enhances seedling emergence in treated soils. In spray applying PAM, it is desirable to apply stock solution at high concentrations to minimize the total volume of solution applied per unit area. We tested the hypothesis that PAM solutions would alter spray characteristics of nozzles. It was found that the spray pattern from typical fan-type nozzles was altered significantly as the PAM concentration was increased from zero (pure water) to 1200 PPM, where the spray coalesced into a concentrated stream. The pattern began to change significantly at concentrations between 300 and 600 PPM. Higher pressures are recommended for PAM application at 600 PPM or higher. These results should be useful in designing spray equipment to apply PAM and similar materials to soils for erosion control or plant establishment.