北海道大学 · 農学・生物学
UCHIDA研究室では、土壌微生物と窒素循環の関係に注目し、特に水loggingや施肥管理が土壌からの亜酸化窒素（N₂O）排出に与える影響を、実験的・分子生物学的手法を用いて解明しています。主に農業土壌における微生物コミュニティ構造の変化とその機能的意義、特に窒素循環の主要プロセス（脱窒素作用・窒素固定）とN₂O発生の関係を、土壌種別（アンドソル・フラビソルなど）に解明しています。また、持続可能な農業を実現するためのN₂O排出低減技術（例：堆肥・竹炭の適用）の科学的根拠の構築にも貢献しています。
Figures are computed from collected data and may differ slightly.
The contributions of large N2 O pulses following waterlogging to the annual cumulative N2 O productions were significant in a Fluvisol. To uncover the mechanisms underlying these large N2 O pulses, a Fluvisol sampled from an agricultural field in Japan was subjected to waterlogging during incubation. Larger N2 O emissions were observed in intact soil cores when compared to emissions from sieved soils, indicating the importance of soil properties. The most important factor controlling the magnitu
In this review, the current knowledge of nitrous oxide (N2O) emissions from soybean (Glycine max (L.) Merr.)ecosystems, particularly on postharvest N2O emissions, is summarized and controlling factors of postharvest N2O emissions from soybean ecosystems are discussed. A new biological method to mitigate N2O emission is also presented. The latest (2006) guidelines of the Intergovernmental Panel on Climate Change (IPCC) concluded that N2O emissions derived directly from biological nitrogen (N) fix
Abstract Soil microorganisms are important for the maintenance of soil health and related functions. Agricultural management practices such as land use, season, and fertilizer affect soil microbial community structures. However, the effect of these management practices on soil microorganisms and related functions, influenced by regionally different soil types, is still not clear. Hence, the study was conducted in an Andosol (volcanic soil) dominated agricultural region in a cool temperate climat
Legumes add not only nitrogen (N), but also carbon (C) to soils, so their effects on the soil microbial community may be different from those of chemical fertiliser. Soil microbes often compete with plants for N when excess C is applied due to their increased N immobilisation potentials and denitrification. In the present study we evaluated the effects of the 9-year use of a green manure legume (hairy vetch; Vicia villosa) in a greenhouse tomato system on soil microbial community structures as w
Nitrogen (N) fertilizers applied on agricultural fields are an important source of nitrous oxide (N2O). The use of coated fertilizer is known to mitigate fertilizer derived N2O emissions; however, according to previous studies, the effectiveness of coated fertilizer as a mitigation option varies depending on the soil types. We hypothesized that this variability was due to the contribution of nitrification and denitrification to N2O emissions depending on the soil and fertilizer types. Two contra
Hairy vetch (Vicia villosa Roth ssp. dasycarpa) mulch is widely used as green manure. This mulch decomposes in the soil and produces nitrous oxide (N2O) emissions. Although rice husk charcoal can be used as a soil conditioner to reduce N2O emissions, the effects of charcoal on the decomposition of vetch mulch and consequent N2O emissions have not been well studied. We conducted an incubation experiment to examine how the decomposition of vetch mulch, charcoal amendments and two soil moisture reg
Cow urine deposition on pasture soils is a major source of N-related environmental impacts in the dairy farming systems. The urine-N can potentially be lost to the ground water as nitrate (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">N</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn mathvariant="normal">3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mo>-</mml:
Abstract Grazed pastures contribute significantly to the global nitrous oxide (N 2 O) budget. In grazed pastures, the highest N 2 O emission rates are often reported during winter when soils are wet. This review discusses the current knowledge about factors controlling winter N 2 O emissions in grazed pastures. High N 2 O emissions from pastures during winter are also observed from winter‐housed animal feeding systems. At near‐zero temperature, N 2 O producing microbial activity is limited but s
Legumes, including hairy vetch (Vicia villosa Roth), are widely used as green manures. They fix nitrogen (N) and provide the N to other crops when they decompose, and thus are considered alternatives for chemical N fertilizers. However, N-rich plant residues, including hairy vetch, are also sources of soil nitrous oxide (N2O) emissions, a greenhouse gas. On one hand, rice (Oryza sativa L. ssp. japonica) husk biochar is widely used as a soil conditioner in Japan and has been reported as a tool to
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