Effects of a New Polysaccharide-Based Amendment on Furrow Irrigation Infiltration and Erosion

Abstract

Controlling soil erosion on furrow-irrigated fields is essential to maintain productivity and reduce off-site impacts. Identifying effective alternatives to polyacrylamide (PAM) is desired for continued, affordable irrigation erosion control. We compared the effectiveness of a new polysaccharide/PAM amendment with water-soluble, high molecular weight, anionic PAM in two furrow-irrigated field tests in southern Idaho. Test 1 evaluated three rates of the polysaccharide/PAM amendment (6, 12, and 18 mg L-1 of polysaccharide/PAM), two rates of PAM (2 and 10 mg L-1 of PAM), 10 mg L-1 polysaccharide, and a control during two irrigations in a fallow field. Treatments were applied as a solution with furrow inflow water during irrigation advance. Test 1 results indicated that polysaccharide/PAM amendment could improve infiltration and reduce sediment loss compared to untreated furrows, but its effectiveness seemed to diminish when amendment application stopped. Polysaccharide alone did not significantly effect infiltration, runoff, or sediment loss compared to the control for either irrigation, whereas the polysaccharide/PAM amendment significantly increased infiltration and reduced sediment loss for one irrigation. Test 2 compared polysaccharide/PAM amendment and PAM, both applied at either 2 mg L-1 (active ingredient) continually during irrigation (dissolved treatments) or as a 20 g per furrow of dry material near the furrow inflow point (patch treatments), during four irrigations on a dry bean field. Both amendments significantly increased cumulative infiltration and decreased cumulative runoff and sediment loss compared to untreated furrows. Dissolved polysaccharide/PAM increased cumulative infiltration 19% compared to the control, while dissolved PAM, patch polysaccharide/PAM, and patch PAM treatments increased cumulative infiltration 13%, 11%, and 7%, respectively, compared to the control. Dissolved and patch PAM and dissolved and patch polysaccharide/PAM treatments significantly reduced cumulative sediment loss 98%, 90%, 65%, and 49%, respectively, compared to the untreated furrows. These test results indicate that the polysaccharide/PAM amendment can be used as an alternative, albeit less effective, to PAM for reducing sediment loss from furrow-irrigated fields.