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United States Department of Agriculture

Agricultural Research Service

Title: Five-Year Research Summary Using Pam in Furrow Irrigation

Authors
item Lentz, Rodrick
item Sojka, Robert

Submitted to: University of Idaho Miscellaneous Publication
Publication Type: Proceedings
Publication Acceptance Date: May 6, 1996
Publication Date: N/A

Interpretive Summary: Furrow-irrigation-induced soil erosion is a serious threat to sustainable agriculture globally. Studies using polyacrylamide (PAM) in furrow irrigation are summarized. In the optimal treatment, PAM is added to inflows at 10 ppm as water first flows down the furrow, then PAM application is stopped when runoff begins. This treatment reduces furrow soil loss by 94%, increases net infiltration 15%, increases lateral wetting extent 25%, reduces total phosphate losses from fields by 75%, and reduces field losses of some pesticides. PAM's erosion control efficacy decreases as the proportion of sodium ions in the irrigation water increases, but PAM's efficacy increases with increasing calcium and magnesium ion concentration. Studies that examined the fate of PAM added to furrow streams is summarized. While PAM was being injected into furrow streams, its concentration decreased with distance downstream from the application point. The PAM concentration in solution-treated furrows decreased to near zero in less than 30 minutes after PAM injection was curtailed. In another study, off-standard PAM treatments were shown to be equally effective as standard approaches, for controlling furrow erosion. Field studies have demonstrated that PAM technology is a safe, economical practice that dramatically reduces soil losses and nonpoint source pollution from furrow irrigation.

Technical Abstract: Furrow-irrigation-induced soil erosion is a serious threat to sustainable agriculture globally. Field studies have demonstrated that small concentrations of polyacrylamide (PAM) in irrigation water greatly reduces soil loss from irrigated furrows and increases intake. The PAM used for this application is described, and safety concerns discussed. When used at recommended rates PAM is non-toxic , and it has previous EPA and FDA approval for use in food and water additive applications. PAM effects on furrow irrigation processes are summarized. Optimal PAM treatments reduce furrow soil loss by 94%, increase net infiltration 15%, increase lateral wetting extent 25%, reduce total phosphate losses from fields by 75%, and reduce field losses of some pesticides. PAM's erosion control efficacy decreases as sodium adsorption ratio of the irrigation water increases, but generally it efficacy increases with increasing divalent cation concentration. Studies that examined the fate of PAM added to furrow streams is summarized. During PAM application, runoff from solution-treated furrows contained 6-10 mg/L PAM, while runoff from dry-PAM treated furrows contained 1-6 mg/L. While PAM was being injected into streams, its concentration decreased with distance downstream from the application point. The PAM concentration in solution-treated furrows decreased to the minimum detection limit less than 30 minutes after PAM injection was curtailed. In another study, off-standard PAM treatments were shown to be equally effective as standard approaches, for controlling furrow erosion.

Last Modified: 12/22/2014
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