Abstract
We investigated pollution loadings in two groups of paddy fields (5.1 and 5.6 ha) in Moriyama City in Shiga Prefecture, Japan. The results are as follows: 1) Net loadings of total nitrogen (T-N), total phosphorus (T-P), total organic carbon (TOC), and suspended solids (SS) during the irrigation period in the two groups of paddy fields were 44-105 g•ha-1•d-1, 27-28 g•ha-1•d-1, 214-276 g•ha-1•d-1, and 3918-4113 g•ha-1•d-1, respectively. 2) The percentages of the pollution loadings during rain events in total pollution loadings during the irrigation period are app. 35-50%. 3) Pollution loadings determined by observations of groups of paddy fields are higher than those determined by observations of one paddy field or using lysimeters because of soil erosion of banks around drainage channels and resuspension of bottom sediments at drainage channels on rainy days.
