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 (310Kb)
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| Haruo Tsunita | |
| Head | |
| Laboratory of Environmental Impact Assessment, | |
| Department of Environmental Planning, | |
| National Institute of Agro-Environmental Sciences, | |
| Ministry of Agriculture, Forestry, and Fisheries | |
| 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8604 Japan | |
| Tel: +81-298-38-8276, Fax: +81-298-38-8199 | |
| E-mail tsuruta@niaes.affrc.go.jp |
¡¡15,551,000 Yen
(1) The methane flux from rice paddy fields was measured at 8 sties in China during 1993-1997. The methane emission rate was in a range of 1.6-148gCH4m-2y-1, and was different from site to site, and year to year. The large methane emission rate was measured from un-drained rice paddy fields in non rice growing season, and possibly contributes to the total emission rate in China.
(2) An intensive five-year (1995-1999) filed program on the N2O flux measurement in an onion field in Hokkaido, Japan showed that the emission ratio of N2O-N to the total amount of nitrogen fertilised into the soils was 1-3 %, much higher than in the other region of Japan. And the flux of N2O was much higher in the latter half of vegetation, indicating that N2O could be produced by denitrification process, because a part of nitrogen fertiliser was remained in the deeper soils as NO3- in high concentration.
(3) The first field measurement of N2O flux from soils in a forest in Hachi-oji located near Tokyo showed an annual N2O emission rate was of 0.42¡Á0.62 kg N ha-1, much higher than in the other temperate region such as Europe and North America. The concentration of NO3- in stream water was positively correlated with N2O flux in forest soils, and could be a good indicator to predict the rate of N2O flux from forest soils on a watershed scale. It strongly suggests that the phenomenon of 'nitrogen-saturation' is of a crucial importance for N2O emission from forest ecosystems.
¡¡Rice Paddy fields, China, Methane emission, Hokkaido, Onion fields, Nitrous oxide emission, Forest soils, Stream water, Nitrate ion.