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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #90834
Title: POLYACRYLAMIDE EFFECTS ON INFILTRATION IN IRRIGATED AGRICULTURE

Author
item Sojka, Robert
item Lentz, Rodrick
item ROSS, CRAIG
item Trout, Thomas
item Bjorneberg, David - Dave

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Using polyacrylamide (PAM) following the NRCS conservation practice standard increases infiltration in furrow irrigation. PAM (10 ppm during water advance) nearly precludes detachment and transport of soil in furrows. If any sediment is entrained in the flow, it is readily flocculated in the presence of PAM and settles to the furrow-bottom in loose pervious structures. We hypothesized that depositional surface seals that block pores are reduced or made more permeable with PAM. On Portneuf silt loams (coarse-silty, mixed, mesic Durixerollic Calciorthid) furrow irrigation net infiltration increased 15%. Net increases on finer textured soils were generally higher. Furrow streams containing more than 5 g/L sediment reduced infiltration and infiltration rate more than five fold compared to streams of clean water. Tension infiltrometry confirmed that PAM's maintenance of open pores to the furrow surface provides the infiltration increase mechanism. Infiltration rates at 40 and 100 mm tension in PAM-treated furrows were double the rates of control furrows. Recirculating infiltrometer data showed a 30% infiltration increase with PAM-use and infiltration was inversely related to maximum sediment concentration in the flow. Furrow inflow of 45 L/min with PAM-treatment decreased stream advance time 13% while reducing sediment loss 76% compared to untreated 23 L/min inflows. Use of PAM in sprinkler irrigation streams reduced runoff 70% and sediment loss 75%, but tension infiltration measurements were inconsistent, suggesting changes in surface sealing effects with sprinkler application of PAM are transient.

Technical Abstract: Using polyacrylamide (PAM) following the NRCS conservation practice standard increases infiltration in furrow irrigation. PAM (10 ppm during water advance) nearly precludes detachment and transport of soil in furrows. If any sediment is entrained in the flow, it is readily flocculated in the presence of PAM and settles to the furrow-bottom in loose pervious structures. We hypothesized that depositional surface seals that block pores are reduced or made more permeable with PAM. On Portneuf silt loams (coarse-silty, mixed, mesic Durixerollic Calciorthid) furrow irrigation net infiltration increased 15%. Net increases on finer textured soils were generally higher. Furrow streams containing more than 5 g/L sediment reduced infiltration and infiltration rate more than five fold compared to streams of clean water. Tension infiltrometry confirmed that PAM's maintenance of open pores to the furrow surface provides the infiltration increase mechanism. Infiltration rates at 40 and 100 mm tension in PAM-treated furrows were double the rates of control furrows. Recirculating infiltrometer data showed a 30% infiltration increase with PAM-use and infiltration was inversely related to maximum sediment concentration in the flow. Furrow inflow of 45 L/min with PAM-treatment decreased stream advance time 13% while reducing sediment loss 76% compared to untreated 23 L/min inflows. Use of PAM in sprinkler irrigation streams reduced runoff 70% and sediment loss 75%, but tension infiltration measurements were inconsistent, suggesting changes in surface sealing effects with sprinkler application of PAM are transient.