抄録
The mechanisms of nitrate leaching from a nitrogen-limited watershed to a stream on Imizu Hill were studied. High concentrations of nitrate in the stream water were observed not only episodic events but also low flow rate condition in the stream. While watershed of this stream is on nitrogen-limited condition, high concentrations of nitrate (242 μeq/l) were observed in the surface (0.3 m of depth) soil water. When high concentrations of nitrate in the stream water i.e. over 20 μeq/l were observed, a rapid percolation of rain water into the depth of 1 m could be seen by soil temperature profile. It seems that the watershed turn to nitrogen-saturate condition from nitrogen-limited condition when rapid percolation of soil water often occurred.
