Submitted to: Advances in Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2006
Publication Date: March 1, 2007
Citation: Sojka, R.E., Bjorneberg, D.L., Entry, J.A., Lentz, R.D., Orts, W.J. 2007. Polyacrylamide (PAM) in agriculture and environmental land management. Advances in Agronomy. 92:75-162. Interpretive Summary: Since the early 1990s relatively high molecular weight, water soluble, anionic polyacrylamide, usually refered to as “PAM,” has been successfully deployed for a number of soil and water management uses with great success. The two most versatile uses have been the reduction of erosion, especially in irrigated agriculture, and the manipulation of water infiltration into soil. Use of PAM for these applications has proven less expensive and usually more effective than most traditional management approaches, and has seen ready acceptance by the soil and water management community. The dominant literature suggests that PAM is entirely safe to use in the environment and carries little or no risk to humans if applied responsibly. This article gives a comprehensive history of the development of recent PAM technology, placing it in the context of previous soil amendments, discussing user insights, the scientific basis of its function in soil and water, environmental and hygiene considerations and provides some consideration of likely future extensions of PAM technology to additional new and novel applications.
Technical Abstract: Anionic polyacrylamide (PAM) has been sold since 1995 to reduce irrigation-induced erosion and enhance infiltration. Its soil stabilizing and flocculating properties improve runoff water quality by reducing sediments, N, dissolved reactive P (DRP) and total P, chemical oxygen demand (COD), pesticides, weed seeds, and microorganisms in runoff. PAM used for erosion control is a large (12-15 Mg per mole) water soluble (non-crosslinked) anionic molecule, containing <0.05% acrylamide monomer. In a series of field studies, PAM eliminated 80-99% (94% avg.) of sediment in runoff from furrow irrigation, with a 15-50% infiltration increase compared to controls on medium to fine textured soils. Similar but less dramatic results occur with sprinkler irrigation. In sandy soils infiltration is often unchanged by PAM or can be slightly reduced. Typical seasonal application totals in furrow irrigation vary from 3 to 7 kg per ha. Research has shown little or no consistent adverse effect on soil microbial populations. Some evidence exists for PAM-related yield increases where infiltration was crop-limiting, especially in field portions having irregular slopes, where erosion prevention eliminated deep furrow cutting that deprives shallow roots of adequate water delivery. Modified water management with PAM shows great promise for water conservation. High effectiveness and low cost of PAM for erosion control and infiltration management, coupled with easier implementation than traditional conservation measures, has resulted in rapid adoption. About 800,000 ha of U.S. irrigated land use PAM for erosion and/or infiltration management. In recent years PAM has been deployed for uses beyond agricultural erosion control, including construction site erosion control, use in storm water runoff ponds to accelerate water clarification, soil stabilization and dust prevention in helicopter landing zones and various other high traffic military situations. Among the newest topics being researched is the use of PAM to reduce ditch, canal, and pond seepage, using specific application protocols that take advantage of its increase of water viscosity at higher concentrations.