著者

山本 富久 中曽根 英雄 黒田 久雄 加藤 亮

出版者

公益社団法人 日本水環境学会

雑誌

水環境学会誌 (ISSN:09168958)

巻号頁・発行日

vol.29, no.9, pp.561-564, 2006 (Released:2010-01-09)

参考文献数

31

被引用文献数

1

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We surveyed the water quality of irrigation reservoirs in a tea field catchment. The study area was located in Shizuoka Prefecture, Japan. Water in some of the reservoirs showed alkalinity because of the photosynthesis of aquatic plants. On the other hand, water in one irrigation reservoir showed acidity because of nitrogen fertilizer. The NO3-N concentration increased how many times owing to large runoff from a watershed when rainfall was strong and heavy accumulation. The Changes in NO3-N concentration were small throughout the season when was light rainfall. The average of NO3-N concentration in the irrigation reservoirs was about 5 mg·l-1.

著者

山本 富久 中曽根 英雄 松沢 康宏 黒田 久雄 加藤 亮

出版者

公益社団法人 日本水環境学会

雑誌

水環境学会誌 (ISSN:09168958)

巻号頁・発行日

vol.27, no.5, pp.329-336, 2004-05-10 (Released:2008-01-22)

参考文献数

27

被引用文献数

1 1

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The water quality and discharge from a tea field area in Shizuoka were measured daily and the outflow loads of fertilizer components in runoff water estimated. The results are as follows: The amount of nitrogen fertilizer applied was about 1000kg·ha-1·yr-1 in the tea field. The annual of T-N effluent load from the tea field was 531kg·ha-1·yr-1 and it was 49% of the amount nitrogen fertilizer applied. 97% of the T-N load was composed of the NO3-N load. Its outflow load, which consisted of storm water, was 51%. The outflow NO2-N and NH4-N loads were small in the first half of the investigation period. The T-P outflow load from the tea field was 0.18kg·ha-1·yr-1 and the leaching rate was very low, at 0.05%. Most of the phosphate fertilizer was absorbed by the red-yellow soil in the tea field. The average T-P concentration was as low as 0.01 mg·l-1. However, the T-P concentration was very high after heavy rain in June and September of 2000. Storm water had a T-P outflow load concentration of 64%. The K+ outflow load was estimated to be 89kg·ha-1 for the year. The leaching rate was 14%. The percentage was very low because K+ was absorbed by surface soil containing clay minerals. The annual Mg2+ and Ca2+ outflow loads were 292kg·ha-1·yr-1 and 266kg·ha-1·yr-1, respectively. Their leaching rates were 63% and 26%, respectively.

著者

山本 富久 中曽根 英雄 松沢 康宏 黒田 久雄 加藤 亮

出版者

公益社団法人 日本水環境学会

雑誌

水環境学会誌 (ISSN:09168958)

巻号頁・発行日

vol.28, no.6, pp.399-404, 2005-04-10 (Released:2008-01-22)

参考文献数

51

被引用文献数

1 1

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The study area was located in the Makinohara collective tea fields in Shizuoka, Japan. There are flourishing tea industries in this area. The quality and level of the groundwater were observed from Jun. 2002 to Sept. 2003 and examined on the basis of hydrogeology. The Makinohara plateau comprises of clay layers between gravel beds. It yielded discontinuous water qualities caused by perched water in a geological structure. The average concentrations of T-N and NO3-N in the surface water were 26.4 mg·l-1, 23.8mg·l-1, respectively. In contrast, for the groundwater, these concentrations were 17.2 mg·l-1 and 12.6 mg·l-1, respectively. The average concentrations of T-P were 0.012 mg·l-1 in the surface water and 0.022 mg·l-1 in the groundwater. This difference is caused by the dilution effect and release of phosphorus from on aquifer. The annual groundwater effluent loads of nitrogen and phosphorus from the catchments of the Makinohara plateau were 406 t·y-1 and 0.7 t·y-1, respectively.