Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: September 1, 2000
Publication Date: N/A
Interpretive Summary: When added in very small quantities to irrigation water, a water soluble, nontoxic polymer, PAM, effectively reduces erosion in irrigation furrows. Furrow irrigation supplies water to more than 3 million acres of crops in the U.S. Little is known about PAM's ability to control erosion on fields that have appreciable surface plant residue cover, yet sustainable agricultural practices often leave residue on the soil surface. This study shows that use of PAM in straw-residue bearing furrows increased PAM's erosion control effectiveness and that the combined practice, PAM plus straw worked equally well, whether small or large amounts of straw were present. This information is important because it will help farmers reduce furrow irrigation-induced erosion and field runoff losses of sediment and associated agrochemicals, and help prevent pollution of natural surface waters.
Technical Abstract: Water soluble anionic polyacrylamide (PAM) is a highly effective erosion deterrent in furrow irrigation, but little is known about the effect of plant residue on PAM efficacy. We hypothesized that increasing plant residue in irrigation furrows would decrease PAM's ability to control erosion. Treatments included furrows with 3.2 g/m and 10 g/m straw applications irrigated with PAM or untreated water, and conventionally irrigated furrows (no PAM and no straw). Five irrigations were monitored on a field with 1.5% slope and silt loam soil (Durinodic Xeric Haplocalcids). PAM was applied as a 33-g granular patch at the furrow inflow end (1 kg active ingredient per ha). Irrigation inflows of 23 L/min were cutback to 15 after runoff began. Adding more straw or adding PAM to straw-treated furrows decreased furrow sediment loss and increased net infiltration, but only for the first two irrigations after treatment. For fresh furrows, straw treatments reduced sediment loss an average 86% and straw + PAM reduced sediment loss nearly 100%, compared to conventionally irrigated furrows. High-straw+PAM and low-straw+PAM treatments produced the same furrow sediment losses and net infiltration amounts, i.e. increasing plant residues in furrow did not decrease PAM's efficacy on these soils.