Surface water chemistry, particularly concentrations of NO−3 and DO and δ15N values, near a tea plantation in Kyushu, Japan

Hiroyuki,; Hirata, Tatemasa; Matsuo, Hiroshi; Nishikawa, Masataka; Tase, Norio

doi:10.1016/s0022-1694(97)00076-0

Cited by 27 publications

(20 citation statements)

References 9 publications

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“…In contrast, DC recorded mean NO 3 -N concentration of 8.2 mg/l and 4.3 mg/l in the NRS and the RS, respectively, showing a significant decrease (p = 0.003) during the RS. Observed NO 3 -N reductions in the DC were directly opposite to most agricultural drainages where NO 3 -N concentration tends to be high during the summer season in response to increased NO 3 -N levels of TPs (Ii et al, 1997). The cause of the disparity was high volumes of denitrified waters from draining PFs in the middle valley, which drained into DC diluting NO 3 -N concentrated drainage water from TPs, just before DC discharges into the R. In this regard, deliberate designing of DCs from TPs to pass through PFs (or linking DCs of TPs to DCs of PFs), as in the study area would result in significant spatial decrease in NO 3 -N concentration of flows from TPs to the R due to dilution effect, especially during the RS.…”

Section: Water Quality Characteristicsmentioning

confidence: 79%

“…These include: optimal chemical N fertilisers application rates of 540 kg N ha -1 year -1 (Hirono et al, 2009;Nagumo et al, 2012), use of high N efficient fertilisers (Ii et al, 1997;Oh et al, 2006), conjunctive use of carbonates with N fertilisers (Nakasone et al, 2002), split N application methods, and use of organic fertilisers and green manure (Kumazawa, 2002). While there has been a significant reduction of N in water bodies surrounding tea plantations due to these concerted efforts; a follow-up study by Hirono et al (2009) observed that N especially NO 3 -N concentration of water resources from tea growing regions remained above 10 mg/l (Japan environment water quality threshold).…”

Section: Introductionmentioning

confidence: 99%

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Robust optimal model for sustainable joint production of green tea and paddy rice in Japanese agricultural watersheds

Mabaya

Unami

Takeuchi

et al. 2017

IJISD

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Abstract:In Japanese hilly agricultural watersheds, green tea is a profitable crop, whereas paddy rice cannot endure without subsidies. Environmentally, green tea plantations are the highest nitrate pollutant emitters to water bodies, whereas paddy fields are the most significant nitrogen sinks. This study investigates the effectiveness of diverting nitrate-contaminated drainage water from upland tea fields to the lowland paddy fields, in terms of reduction of downstream pollution and rice production cost, using the robust optimal model. The model optimally maximises diversions to reduce nitrate pollution to the adjacent rivers, and is environment risk averse to possible malfunctioning denitrification processes in the respective paddy fields. The application shows increased diversions to paddy fields during the rice growing season, thereby facilitating rice plants to have optimal access to substantial amounts of nitrogen nutrients and water. Thus, the robust optimal model has the potential to support sustainable joint production of the two crops.Keywords: robust optimisation; sustainable production; green tea; paddy rice; agricultural drainage water; nitrogen pollutants.Reference to this paper should be made as follows: Mabaya, G., Unami, K., Takeuchi, J., Fujihara, M. and Yoshioka, H. (2017) 'Robust optimal model for sustainable joint production of green tea and paddy rice in Japanese agricultural watersheds ', Int. J. Innovation and Sustainable Development, Vol. 11, No. 1, 70 G. Mabaya et al.Biographical notes: Goden Mabaya, MSc (Water Science and Engineering) 2012 UNESCO-IHE, Netherlands, is a PhD student in Water Resources Engineering at the Graduate School of Agriculture, Kyoto University, Japan. He has an extensive technical experience in planning, designing, construction and water management of multiuser irrigation and drainage systems in Africa. His research interests are robust optimisation of integrated agricultural watershed management with an emphasis on environmental sustainability, environmental water quality management, and post-modernisation of irrigation and drainage systems.Koichi Unami, PhD (Agriculture) 1998, Kyoto University, is an Associate Professor at Graduate School of Agriculture, Kyoto University, Japan. His research topics include theories and practices of water resources and environment management in rural areas, with specific emphasis on robustness in decision-making under uncertainty. For example, he determines operation rules for irrigation dams with irregular occurrence of recharge events in the framework of stochastic control. He is also an expert in field studies with different agro-ecological climates in Asia and Africa, such as Lake Biwa Basin of Japan and Volta Basin of West Africa.Junichiro Takeuchi, PhD (Agriculture) 2010, Kyoto University, is an Assistant Professor of Water Resources Engineering at Graduate School of Agriculture, Kyoto University, Japan. His main research interests include fluid flow and solute/energy transport through porous media and environmentally so...

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Section: Water Quality Characteristicsmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Robust optimal model for sustainable joint production of green tea and paddy rice in Japanese agricultural watersheds

Mabaya

Unami

Takeuchi

et al. 2017

IJISD

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“…In pursuit of high-quality tea, it has been the general tendency by green tea farmers in Japan to apply heavy dressing of N fertilisers. N application rates of 1000-2500 kg N ha -1 year -1 are reported to have been applied to green tea crop (Hirono et al 2009;Ii et al 1997;Nagumo et al 2012;Nakasone et al 2002;Oh et al 2006). Thus, N fertiliser applications in green tea plantations have been much higher than any other field crop land use.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, the NO 3 -N concentration in tea plantations tends to be highest in winter and lowest in summer season (Hirono et al 2009). The fluctuation is opposite to drainages, surface and subsurface waters around green tea plantations where NO 3 -N concentration tends to be highest during the summer season (Hirono et al 2009;Ii et al 1997). This water quality problem phenomenon occurs more often when no buffer is present in the lower reaches of the watershed (Vidon et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Robust optimal diversion of agricultural drainage water from tea plantations to paddy fields during rice growing seasons and non-rice growing seasons

Mabaya

Unami

Yoshioka

et al. 2015

Paddy Water Environ

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We investigated seasonal water quality changes on different land uses in a small agricultural watershed dominated with rice and tea crops. Observed NO 3 -N in tea plantations and tea drainage channels was sufficiently high enough to cause downstream water pollution throughout the year. On contrary, significant NO 3 -N reductions were observed in abandoned and active paddy fields, and were highest in active paddy fields during rice growing seasons. Accordingly, a question is posed whether deliberately diverting NO 3 -N contaminated drainage water from tea plantations to paddy fields would be effective a strategy for reducing downstream water pollution. NO 3 -N ratios reduced in paddy fields are however neither distinct nor known in advance, and this uncertainty could consequently lead to further environmental risks like NO 3 -N leaching and production of greenhouse N 2 O gas. We assume that NO 3 -N reduction rates of paddy fields and drainage canals are constrained in an ellipsoidal set of uncertainty. A portfolio optimisation problem is formulated to determine optimal rates of diversion from tea drainage channel into paddy fields. The problem is numerically solved in robust optimisation approach by maximising minimum NO 3 -N reduced under uncertainty. An application demonstrated that robust approach allocates different optimal rates of diversion to hedge the risk of possible malfunctioning of NO 3 -N reduction processes. Overall worst-case NO 3 -N reduction is highest in rice growing season, due to increased drainage water allocations to active paddy fields. The robust optimisation approach has potential to support decision-making processes for reducing NO 3 -N pollution and water demand pressure on water resources, and cost of rice production thereof.

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“…Then the H + ions runoff and create a low pH in the water. Matsuo et al (1992) and Ii et al (1997) first reported the acidification of irrigation reservoirs in a tea field watershed near Kurume City in Fukuoka Prefecture, Japan. He suggested that the long term and great application of ammonium sulfate created acidic reservoirs.…”

Section: Introductionmentioning

confidence: 99%

The impacts of the water quality of the inflow water from tea fields on irrigation reservoir ecosystems

Nakasone

Yamamoto

2004

Paddy Water Environ

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Authors observed that the nitrate nitrogen (NO 3 -N) concentration is approximately 30 mg/L and that the average pH value is 4.3 in a small river in Shizuoka Prefecture, Japan. Further, when there is heavy rain, the pH value of the river water decreases to below 3.5 at times. There is a small irrigation reservoir in the watershed. The reservoir receives this water and mixed with other river water, the pH in the reservoir reaches below 5.0 at times, making it impossible for fauna to survive there. This water is also used for paddy irrigation, however no damage to rice production was reported. The authors clarified the fact that the low pH and high NO 3 -N concentrations were brought about by the overuse of nitrogen fertilizers in tea fields. Further, the authors proposed a model, which can be used to estimate the pH value and the NO 3 -N concentration.

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Surface water chemistry, particularly concentrations of NO−3 and DO and δ15N values, near a tea plantation in Kyushu, Japan

Cited by 27 publications

References 9 publications

Robust optimal model for sustainable joint production of green tea and paddy rice in Japanese agricultural watersheds

Robust optimal model for sustainable joint production of green tea and paddy rice in Japanese agricultural watersheds

Robust optimal diversion of agricultural drainage water from tea plantations to paddy fields during rice growing seasons and non-rice growing seasons

The impacts of the water quality of the inflow water from tea fields on irrigation reservoir ecosystems

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