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ARS Home » Midwest Area » West Lafayette, Indiana » National Soil Erosion Research Laboratory » Research » Publications at this Location » Publication #105276
Title: EFFECT OF POLYACRYLAMIDE MOLECULAR WEIGHT AND CHARGE ON INFILTRATION UNDER SIMULATED RAINFALL

Author
item GREEN, V - PURDUE UNIVERSITY
item Stott, Diane
item Norton, Lloyd
item GRAVEEL, J - PURDUE UNIVERSITY

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2000
Publication Date: 9/1/2000
Citation: Green, V.S., Stott, D.E., Norton, L.D., Graveel, J.G. 2000. Effect of polyacrylamide molecular weight and charge on infiltration under simulated rainfall. Soil Science Society of America Journal. 64:1786-1791.

Interpretive Summary: Soil sealing on agricultural fields is a severe problem worldwide. The ensuing crust formation causes increased surface runoff and erosion, and decreased seedling emergence, resulting in on- and off-site problems affecting producers and communities. One possible soil sealing control measure is the application of polyacrylamide (PAM). Little is known about the interaction of specific PAMs with soils of differing characteristics. This study was conducted to examine the relationship between PAMs of different molecular configurations (molecular weight and charge density) and soils of varying characteristics. We examined PAM charge densities, or percent hydrolysis, at 20, 30, and 40% hydrolysis, and molecular weights of 6,000, 12,000, and 18,000. The soils used were Heiden clay (Udic Haplustert), Cecil sandy loam (Typic Kanhapludult), and Fincastle silt loam (Aeric Epiaqualf). Soil material was exposed to rainfall simulation in the laboratory. Infiltration rate was used as an indicator of soil surface sealing. All three soils responded well to PAM treatments, having higher infiltration rates than the control. PAMs that were 20 & 30% hydrolyzed performed best in maintaining high infiltration rates on Heiden clay. The 12k molecular weight configuration worked best for Cecil sandy loam, regardless of the charge density. Fincastle silt loam showed no preference for a particular PAM configuration. Polyacrylamide increased final infiltration rates of these soils by as much as 3 to 5 fold. Different PAM formulations provided differing degrees of soil protection, varying between soils. Producers, who want to include PAM as part of their management system, will be able to select the PAM molecular configuration most suited to their soil.

Technical Abstract: Soil sealing on agricultural fields is a severe problem worldwide. Increased runoff and decreased seedling emergence cause on- and off-site problems affecting farmers and communities. One possible soil sealing control measure is the application of polyacrylamide (PAM). Little is known about the interaction of specific PAMs with soils of differing characteristics. This study was conducted to examine the relationship between PAMs of different molecular configurations and soils of varying characteristics. We examined PAM charge densities (CD) of 20, 30, and 40% hydrolysis with molecular weights of 6, 12, and 18 Mg mol-1. The soils used were Heiden clay (fine, smectitic, thermic Udic Haplustert), Cecil sandy loam (clayey, kaolinitic, thermic Typic Kanhapludult), and Fincastle silt loam (fine-silty, mixed, mesic Aeric Epiaqualf). Soil material was exposed to rainfall simulation in the laboratory. Infiltration rate was used as an indicator of soil surface sealing. All three soils responded well to PAM treatments, having higher infiltration rates than the control. Twenty and 30% CD PAMs performed best in maintaining high infiltration rates on Heiden clay. The 12 Mg mol-1 MW configurations worked best for Cecil sandy loam. Fincastle silt loam showed no preference for a particular PAM configuration. Polyacrylamide increased final infiltration rate by as much as 3 to 5 fold for these soils. Different PAM formulations provided differing degrees of soil protection, varying between soils. Understanding the interaction of different soils with various PAM configurations will enable PAM users to select the best PAM product for their specific soil conditions.