多摩丘陵における表面流出水中の窒素化合物の挙動
1986 年 47 巻 1 号 p. 17-26
詳細
1986 年 47 巻 1 号 p. 17-26
Behaviour of nitrogen compounds in surface runoff water was investigated at small watershed (Hs-1) of Tama Hill during 1976-1982.
Budgets of nitrogen compounds were estimated by nitrogen content in precipitation (rain in the open plot, throughfall and stemflow) and surface runoff water during May-September 1982. Runoff coefficient of water (ratio of amount of surface runoff water to that of precipitation) amounted to 63%. Input of nitrogen by throughfall and stemflow was 1.6-2.4 times larger than that by rainfall in the open plot.
Runoff coefficients of NH4-N and NO3-N were 3% and 480%, respectively. Assuming that NH4-N in rain water is oxidized to NO3-N in soil and eluted to surface runoff water, runoff percentage of NO3-N becomes 270%. Average runoff coefficient of nitrogen during five years amounted to 180%. At the experimental watershed of the Tama Hill, the nitrogen output by surface runoff water was larger than the input by precipitation, suggesting that the watershed is not in the state of stable or climax forest ecosystem.
