流出水の連続測定による静岡県牧ノ原茶園地帯からの肥料成分の流出負荷量

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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.
2004-05-10