Polymers check furrow erosion, help river life

Each year, irrigation runoff from West Stanislaus County farmland carries about 1.2 million tons of sediment into the San Joaquin River. The sediment contains pesticide residues which threaten aquatic wildlife. One solution for this problem is to inject polyacrylamide polymers into irrigation water, a practice which reduces soil erosion and has economic benefits to the grower, such as increasing infiltration rates. In recent trials, this practice reduced soil erosion and runoff water from a furrow-irrigated spinach field. Polyacrylamide-treated furrows had a 10% lower outflow rate than the untreated furrows. In addition, the polyacrylamide flocculated the suspended soil particles; on average, 99.7% settled out compared to soil particles in untreated furrows.