Groundwater Chemistry Near a Tea Plantation in the Center of Shizuoka Prefecture, Japan

Tanaka, Takao; Hiroyuki,; Hirata, Tatemasa; Nishikawa, Masataka; Nakajima, Tsugio; Umehara, Kouichi; Ogawa, Yoshikatsu

doi:10.2208/prohe.45.355

Cited by 3 publications

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“…Figure 4 shows the relationship between median NO 3 ‐N concentrations and median pH values. The median pH values decreased with an increase in NO 3 ‐N concentrations, in agreement with the findings of Tanaka et al. (2001).…”

Section: Resultssupporting

confidence: 89%

“…Many studies on water quality around intensive tea‐growing areas in Japan have since been conducted. Tanaka et al. (2001) detected high concentrations of NO 3 ‐N (the highest concentration was approximately 80 mg N L −1 ) in the groundwater around a tea‐growing area in the central part of Shizuoka Prefecture, and they reported that a reduction in the amount of fertilizer applied to tea fields is needed to reduce the concentrations of NO 3 ‐N to allowable levels.…”

Section: Introductionmentioning

confidence: 99%

“…Many studies on water quality around intensive teagrowing areas in Japan have since been conducted. Tanaka et al (2001) detected high concentrations of NO 3 -N (the highest concentration was approximately 80 mg N L )1 ) in the groundwater around a tea-growing area in the central part of Shizuoka Prefecture, and they reported that a reduction in the amount of fertilizer applied to tea fields is needed to reduce the concentrations of NO 3 -N to allowable levels. Ogawa et al (2003) found a significant relationship between the proportion of acreage of tea fields in the catchment basin and the concentrations of NO 3 -N and reported that the nitrate pollution level in a basin will be improved if NO 3 -N loads from tea fields are reduced.…”

Section: Introductionmentioning

confidence: 99%

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Trends in water quality around an intensive tea-growing area in Shizuoka, Japan

Hirono¹,

Watanabe²,

Nonaka³

2009

Soil Science and Plant Nutrition

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In the cultivation of tea in Japan, compared with other crops, large amounts of nitrogen have been applied as fertilizer, resulting in an increase in nitrate-nitrogen (NO 3 -N) concentrations in the groundwater around intensive tea-growing areas. To address this problem, the amounts of nitrogen fertilizer applied to tea fields have been reduced in recent years. It has been reported that the amount of fertilizer used in 1993 was more than 1,000 kg N ha, but had decreased to 600 kg N ha )1 in 2002 in Shizuoka Prefecture. In the present study, the effect of a reduction in nitrogen fertilizer use in an intensive tea-growing area in Shizuoka Prefecture on surrounding water systems was assessed. A seasonal Mann-Kendall test, one of the most widely used non-parametric tests, was applied to 10-year datasets of monthly pH and NO 3 -N concentrations from 16 sites, including drainages, springwater, groundwater and streams, for trend analysis. The results showed that there were significant downward trends (two-sided test at a 5% level) in NO 3 -N concentrations at most of the sites, and the seasonal Kendall slope estimator b, which represents the magnitude of the trend, ranged from )2.9 to )0.8 in drainages, from )2.6 to )1.8 in springwater and from )0.6 to )0.3 mg N L )1 year )1 in streams. The results of the present study suggested that the efforts made by farmers and authorities to reduce nitrogen fertilizer use in tea fields have resulted in improvements in NO 3 -N concentrations in the surrounding water systems in the study area. In contrast, for pH, significant downward trends were observed at nine of the 16 sites, indicating that water systems in this area have been acidifying, despite a reduction in nitrogen fertilizer use.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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