Submitted to: Transactions of the ASAE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/1/2002
Publication Date: 8/31/2002
Citation: Peterson, J.R., Flanagan, D.C., Tishmack, J.K. Effects of polyacrylamide and gypsiferous material on runoff and erosion. Transactions of the American Society of Agricultural Engineers. 2002. v. 45(4). p. 1011-1019. Interpretive Summary: Soil erosion is a serious problem in the United States and throughout the world. New ways to control runoff and soil loss and reduce sediment leaving from agricultural fields, forest logging areas, and construction sites are needed. This paper describes the results of an experimental study that used different types of surface-applied chemicals, to try to reduce runoff and soil loss. The materials used were polyacrylamide, also known as PAM, and gypsiferous materials. Both of these have been shown in earlier studies to help reduce runoff and soil loss. In this experiment we wanted to see if applying the PAM as a liquid spray and allowing it to dry on the soil would be better at controlling soil erosion than just applying the material as dry granules. We also wanted to see if a ponded fly ash product (Nutra-Ash) would be as effective as commercial gypsum fertilizer at enhancing PAM effectiveness. The various chemical treatments were applied to a silty clay soil in small boxes in the laboratory, and rainfall was applied using rainfall simulators. We found that the commercial gypsum was better than the ponded fly ash at helping PAM to control erosion. We also found that the sprayed PAM was more effective at controlling soil erosion at the beginning of rain storms, but then became less effective with time. The dry PAM was not very effective at controlling soil loss at the beginning of storms, but with time became activated and more effective. These results may help determine the best type of PAM and gypsiferous material to use to control their own soil erosion problem.
Technical Abstract: A lab study compared dry vs. sprayed application of polyacrylamide (PAM) and use of different gypsiferous materials on runoff and sediment yield. Simulated rainfall at an intensity of 70mm/hr was applied for 2 hours to a silty clay soil packed into 32cm X 45cm X 20cm erosion pans. One of the 2 liquid PAM treatments significantly reduced runoff while both liquid PAM treatments significantly reduced sediment yield compared to the control. Sprayed PAM, in combination with gypsum, increased infiltration during the first part of a rainfall event until sufficient rainfall occurred to breakdown the PAM-treated aggregates at which time runoff rate and sediment yield rate approached that of the control. Runoff and sediment yield rate from the granular PAM application were initially similar to the control. However, as time increased, sediment yield reached a maximum and then decreased without a corresponding decrease in runoff. PAM particles became activated during rainfall and acted to stabilize the soil matrix. Gypsum was a better source of electroyte than a class C ponded fly ash, commercially known as Nutra-Ash (NA). Addition of PAM decreased soil erodibility and may be a viable erosion control practice for soils susceptible to flow detachment. Choice of application method should be based on the expected amount and severity of precipitation before vegetation establishment. These results indicate that sprayed PAM application provides immediate erosion control but its effectiveness decreases over time. Dry PAM application was not as effective in the beginning of the experiment, but after sufficient rainfall became activated and showed a decrease in sediment discharge.