Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2006
Publication Date: 11/1/2006
Citation: Flanagan, D.C., Canady, N.H. 2006. Use of polyacrylamide in simulated land application of lagoon effluent: Part 1. Runoff and sediment loss. Transactions of the ASABE. 49(5):1361-1369. Interpretive Summary: Most livestock farmers in the U.S. apply wastes from their animals to the land, where it can provide nutrients for crop growth. Many large livestock operations use large ponds or lagoons to capture wash waters from their animal houses, and this water is then retained for weeks or months, to allow larger pieces of manures to settle out, and also for bacteria to digest some of the wastes. Once these lagoons become full, the relatively clear water solution has to be removed so that additional waste water can be added. Often this effluent water is applied to nearby fields by sprinkler irrigation. And though this water is relatively clear, it still contains elevated amounts of nutrients that can fertilize crops, but that also can contaminate off-site streams and lakes if rainfall and runoff occurs soon after the irrigation application. This experiment studied the effect of using a chemical called anionic polyacrylamide (PAM) in the wastewater irrigation on reducing the loss of runoff and sediment from soil. We found that the PAM addition was very effective at reducing runoff (by up to 66%) on soils having 30% residue cover. Also, the PAM reduced soil loss by as much as 63% on bare soil. This research impacts farmers and others concerned about applications of liquid livestock wastes to soils, and possible runoff and associated sediment and nutrient losses. Use of a small amount of PAM with liquid wastes may be a cost-effective method to ensure much lower risks of field runoff and sediment contamination of nearby surface streams or lakes.
Technical Abstract: Agriculture contributes considerably to water quality problems in the United States. Tillage systems and land application of wastewaters from animal production facilities can increase both sediment and nutrient loadings to surface waters. Sediment transported to surface waters can decrease biodiversity and the usefulness of water for industry, drinking, and recreation. Anionic polyacrylamide (PAM) is a soil amendment that has been shown to reduce soil erosion during rainfall and irrigation. We hypothesized that dissolving PAM in land applied lagoon effluent would reduce runoff and sediment loss in subsequent rainfalls. Swine wastewater from a third stage anaerobic lagoon was mixed with high molecular weight PAM at concentrations of 10 and 20 ppm, and then surface applied to a silt loam soil packed in erosion boxes. A rainfall simulator was used to study PAM's effectiveness at several slope (4 and 8%) and cover levels (0 and 30%). Two consecutive storms were simulated, one having constant rainfall intensity and another having varying rainfall intensity. PAM treatment reduced runoff from covered soils by as much as 66%. The 10 ppm PAM treatment reduced first storm sediment loss by 58% at 4% slopes and 63% at 8% slopes on bare soils. Lagoon effluent irrigation was found to produce higher sediment losses than water irrigation, but PAM treatment reduced sediment losses in lagoon irrigated soils to levels that were comparable to water only irrigations. These results indicate that application of anionic PAM with wastewater during surface irrigation can reduce runoff and erosion during subsequent rainfall events.