ARS | Publication request: FEASIBILITY OF A FLOCCULATION TEST TO MEASURE AQUEOUS POLYACRYLAMIDE ACTIVITY IN IRRIGATED FURROWS

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 16, 1994
Publication Date: N/A

Technical Abstract: To control irrigation-induced erosion, some farm managers in the Western U.S. are amending irrigation furrow inflows with polyacrylamide (PAM) at low concentrations (0-10 g m-3). Current research seeks to determine the fate of PAM once added to furrow water streams. We developed a flocculation-based procedure used to determine PAM activity (i.e. concentration) in furrow water. A kaolinite mineral standard is added to a PAM-amended water sample, agitated, then placed in a spectrophotometer. Flocculation and settling in the suspension as function of transmitted light is monitored over time. PAM concentration was correlated with settling-curve parameters. One parameter, time, needed to initiate suspension clearing (clarity-shift inflection, CSI), was very strongly related (Corr. Coef., 0.91-0.98, P > 0.0001). The procedure can detect as little as 0.1 g m-3 PAM in irrigation water. Another experiment evaluated the effect that small introduced variations (10%) in the analytical routine or sample condition had on measured CSI. The procedure is particularly sensitive to variations in the amounts of kaolinite added, and the volume, dissolved salt content, temperature, and original sediment concentration of the furrow-water sample employed.