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United States Department of Agriculture

Agricultural Research Service

Title: Net and Tension Infiltration Effects of Pam in Furrow Irrigation

Authors
item Sojka, Robert
item Lentz, Rodrick
item Ross, C. - LANDCARE RESEARCH NZ LTD
item Trout, Thomas

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

Interpretive Summary: Polyacrylamide (PAM) used following the NRCS conservation practice standard increases net infiltration. PAM prevents detachment, transport, and deposition of soil in furrows and flocculates any sediment entrained in the flow settling it to the furrow bottom in loose pervious structures. Depositional surface seals that block pores at the soil water interface are greatly reduced. On Idaho Portneuf silt loams net infiltration has generally increased 15%. Net increases on finer textured soils in California have been around 50%. Infiltration rates at slight water tension in PAM-treated furrows were roughly double the rates of control furrows. A technique that estimates steady state furrow infiltration on short furrow segments (recirculating infiltrometer) measured a 30% infiltration increase with PAM-use and infiltration was inversely related to maximum sediment concentration in the flow. Data showed that infiltration sharply decreases if more than 5 grams per liter of sediment are in the initial water advancing down the furrow. This underscores the importance to water management of controlling erosion and irrigating with clean water.

Technical Abstract: Using polyacrylamide (PAM) following the NRCS conservation practice standard increases net infiltration. PAM prevents detachment, transport, and deposition of soil in furrows. Furthermore, any sediment entrained in the flow is flocculated by PAM and settles to the furrow bottom in loose pervious structures. We hypothesized that depositional surface seals that block pores at the soil water interface are greatly reduced. On Idaho Portneuf silt loams (coarse-silty, mixed, mesic Dirixerollic Calciorthid) net infiltration has generally increased 15%. Net increases on finer textured soils are higher. Research in 1995 utilizing 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 roughly double the rates of control furrows. In another study, recirculating infiltrometer data showed a 30% infiltration increase with PAM-use and infiltration was inversely related to maximum sediment concentration in the flow.

Last Modified: 9/21/2014
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