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 II. Nutrient loss. Transactions of the ASABE. 49(5):1371-1381. 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 wastewater 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 losses of soluble and total nutrients (Nitrogen and Phosphorus) from soil. We found that the PAM addition was effectve at reducing losses of soluble ammonium Nitrogen (up to 92%), soluble Phosphorus (up to 71%), and also reduced total (sediment-bound) nutrient losses. This research impacts farmers and others concerned about applications of liquid livestock wastes to soils, and possible off-site nutrient pollution. Use of a small amount of PAM with liquid wastes may be a cost-effective method to ensure much lower risks of Nitrogen and Phosphorus contamination of nearby surface streams or lakes.
Technical Abstract: Land application of agricultural wastewater can contribute to eutrophication of water bodies by increasing the quantities of dissolved and particulate nutrients that are transported in runoff during rain storm events. Anionic polyacrylamide (PAM) is a soil amendment that has been shown to reduce soil erosion and nutrient transport during rainfall and irrigation. We hypothesized that dissolving PAM in land applied lagoon effluent would reduce nutrient losses during subsequent rainfalls. Swine wastewater from a third stage anaerobic lagoon was mixed with PAM at concentrations of 10 and 20 ppm, and then surface applied to soil packed in erosion boxes. A rainfall simulator was used to study PAM's effectiveness at multiple 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. Soluble ortho-P, combined NO2- and NO3--N, NH4+-N, and particulate N and P concentrations were determined in runoff samples obtained during the storms. Under various levels of slope and cover treatment, PAM use reduced NH4+-N loss from 66 to 92%, and reduced ortho-P loss from 32 to 71%. PAM treatment also reduced particulate nutrient losses, including reductions of 28 to 41% for total P. These results indicate that PAM can be effective for controlling surface nutrient losses in the time period immediately following land application of agricultural wastewater.