1999 Fiscal Year Final Research Report Summary
Four-dimensional evaluation of nitrogen burden from agricultural and using Pedometrics
| Project/Area Number |
10460030
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plant nutrition/Soil science
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KOSAKI Takashi Kyoto Univ.Graduate School of Agriculture, Professor, 農学研究科, 教授 (00144345)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Kazunori Chiba Univ.Fac.Horticulture, Associate Prof., 園芸学部, 助教授 (10225807)
INUBUSHI Kazuyuki Chiba Univ.Fac.Horticulture, Professor, 園芸学部, 教授 (00168428)
HATANO Ryusuke Hokkaido Univ.Fac.Agriculture, Professor, 農学部, 教授 (40156344)
YANAI Junta Kyoto Univ.Graduate School of Agriculture, Assistant, 農学研究科, 助手 (00273491)
NAGANAWA Takahiko Shimane Univ.Fac.Life and Environmental Science Associate Prof., 生物資源科学部, 助教授 (80183531)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Pedometrics / Environmental burden / Nitrogen / Soil Properties / Nitrons oxide(N_2O) / Spatial dependency / Within-field variability |
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| Research Abstract |
To establish reasonable method for the evaluation of nitrogen burden from agricultural land to the environment, four-dimensional evaluation of nitrous oxide (N_2O) flux was carried out in a 1 ha agricultural land in Hokkaido, taking spatial and temporal variability of N_2O flux into account. For the spatial analysis, a hundred gas and soil samples were collected hm the field in August, 1999, and N_2O flux and soil physical, chemical fad biological properties were determined. N_2O flux had very high variability and showed moderate spatial dependency with the range of about 50m, suggesting that at least 9 measurements (every 50m) are necessary for the reasonable evaluation of N_2O flux in this field. N_2O flux was generally high at sites with relatively low elevation and was positively correlated with indices representing soil organic matter. For the temporal analysis, N_2O flux was also measured at one site for 5 years, i.e.from 1995 until 1999. N_2O flux was relatively low in spring after fertilization, and relatively high in summer and autumn, accounting for about 20% and 80% of the total emission, respectively. The mechanism of N_2O emission in spring was considered to be nitrification, and that in summer and autumn was considered to be denitrification at the relatively reduced sites in soil aggregates when a part of nitrate was accumulated due to source-sink effect of soil aggregate. A mechanistic model was further established to evaluate N_2O emission based on the estimation of"reduced volume in soil aggregate", and showed high positive correlation with the log-transformed N_2O flux.
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