Application of Surface Cover Materials for Reduction of NPS Pollution on Field-Scale Experimental Plots

A 2-year experimental plot study was conducted in Korea to measure the effect of different surface treatments on runoff and agricultural non-point source (NPS) pollution. The treatments were straw mat conjunctive with polyacrylamide and gypsum (SPG), straw mat (SM) and plastic sheet (PM) mulches. Four plots on a sandy loam, mildly sloped (2–8.4%) soybean field were monitored with respect to runoff and water quality. Average annual rainfall was 1270 mm. Runoff reduction by the SPG and SM treatments ranged from 22.0 to 90.9% and from 50.0 to 68.1%, respectively, compared with runoff from the control. The SM treatment produced less runoff than did the PM treatment. Event mean concentrations did not show any consistent differences between the treatments except for suspended solids (SS), which were always lower than that from the control. The reduction of NPS pollution load by the SPG and SM treatments ranged between 27.6 and 95.0%, and between 38.7 and 96.7%, respectively. The SS reduction by the treatments ranged between 50.0 and 92.2%. The SPG and SM treatments were effective in the control of soil erosion, turbid runoff and other NPS pollution discharge.