Use of Polyacrylamide in Simulated Land Application of Lagoon Effluent: Part II. Nutrient Loss

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 low-concentration, 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 0, 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 with constant and varying rainfall intensities were simulated. 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 34% to 92% and reduced ortho-P loss from 31% to 71%. PAM treatment was also effective in reducing particulate nutrient losses, including reductions of 22% to 72% for total P. These results indicate that PAM can be effective for controlling surface nutrient losses in runoff in the time period immediately following land application of low-concentration agricultural wastewater.