2001 Fiscal Year Final Research Report Summary
Evaluation of Nitrogen Cycling in a Basin Associated with Forest, Grassland and Animal Husbandry, Hokkaido, Japan
| Project/Area Number |
11460028
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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 | HOKKAIDO UNIVERSITY |
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Principal Investigator |
HATANO Ryusuke Hokkaido Univ., Field Science Center for Northern Biosphere, Prof., 北方生物圏フィールド科学センター, 教授 (40156344)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBATA Hideaki Hokkaido Univ., Field Science Center for Northern Biosphere, Asso. Prof., 北方生物圏フィールド科学センター, 助教授 (70281798)
SATOH Fuyuki Hokkaido Univ., Field Science Center for Northern Biosphere, Prof., 北方生物圏フィールド科学センター, 教授 (20187230)
HATA Hiroshi Hokkaido Univ., Field Science Center for Northern Biosphere, Asso. Prof., 北方生物圏フィールド科学センター, 助教授 (30250492)
KURAMOCHI Kanta Hokkaido Univ., Graduate School of Agr, Assist. Prof., 大学院・農学研究科, 助手 (00225252)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Nitrogen Cycling / Watershed / Forests / Grass lands / Croplands / Nitrate leaching / Animal Excreta / N2O emission |
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| Research Abstract |
Expansion of N cycling in ecosystems with increase of human activity impacts on not only regional environments but also global environments. Global warming with increasing emission of N2O, acidification with increasing of NH3 deposition, water pollution with NO3 leaching, degradation of bio-diversity with N load are the problems associated with N cycling in ecosystems. This report discussed about optimum N cycling in agro-forested ecosystems. In order to evaluate optimum amount of N cycling in agro-forested ecosystems, we studied following topics: 1) Impact of N cycling in basin ecosystem complexes on stream water quality; 2) Impact of atmospheric N deposition on forest soil ecosystems; 3) Green house effect gas fluxes in basin ecosystem complexes. Surplus N in agricultural lands and disposal N in regions are major factor determining stream water quality. N flow model was crucial for their evaluation. Unique N load was shown in each land use structure in a basin ecosystem complex. Most
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N load occurred during rainfall and snow melt season. In agricultural land, chemical fertilizer N, which was supplied to the fields within a 10-day before rain, was mainly discharged to the stream. Although animal and human excreta produced with the consumption of feed and food can be used as manure, inadequate composting process resulted in water pollution. Ammonium volatilization induced acidification of forest soils and stream N discharge induces eutrophication of coastal ecosystems. However they depended on soil quality. Acidification was controlled by exchangeable Ca in soils and eutrophication was controlled by Si supply from soils. Soil forming process, which releases both Ca and Si from primary rock minerals to soil solution, was quite important factor for occurrence of both acidification and eutropication. Hokkaido was the specific area in the world for occurrence of large N2O emission from agricultural fields. Denitrification was major process for large N2O emission. Conversion of forested land to crop land increased global warming effect of the land. However, N2O emission through water discharge from agricultural fields was smaller than the values reported previously. According to the above results, it is necessary for us to evaluate optimal N cycling with scenario analysis using N cycling model to describe numerically N flow associated with production and consumption of food and feed in basin ecosystem complex. Less
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