APPLICATION OF SURFACE COVER MATERIALS FOR REDUCTION OF NPS POLLUTION ON FIELD SCALE EXPERIMENTAL PLOTS

摘要

Four fi eld scale experimental plots were prepared. Soil texture was a sandy loam and a varietyof soybean was cultivated. An H-fl ume, an automatic water level gauge and an automaticwater sampler were installed at the outlet of each plot for the measurement of fl ow rate andwater quality. The rainfall of the study area in 2013 was 975.6 mm which was much lowerthan the annual average rainfall of 1,271.8 mm, resulting in less occurrences in rainfall-runoffevents. Rainfall-runoff events occurred three times during the rainfall event of 4~5 July, 23and 24 August. NPS pollution discharge of the plots and the reduction effect of selected BMPswere analyzed during these events. The reduction effect of straw mat and soil amendments(PAM and Gypsum) on runoff ratio ranged between 38.2 and 92.9% (average 71.6%). TheNPS pollution load reduced between 27.7 and 96.4% (average 71.3%) by the treatment whencompared with those of control plot. Soybean yield (2,133.3 kg/ha) of the straw mat coveredplots increased by 14.3% when compared with control (1,866.7 kg/ha). The effect of strawmat on the yield was not economically viable if the material and accompanying labor costswere considered although the environmental effect was very signifi cant. It was suggestedto continue the study for years to refl ect both low to high annual rainfall variation. The datacollected and analysed in this study together with the similar data collected from differentsoil textures and crops can be a fundamental reference for the expansion of the results fornationwide application and the development of NPS pollution management policies.