Nitrous oxide emissions from pastures during wet and cold seasons. (6th May 2015)

• Record Type: Journal Article
• Authors: Uchida, Yoshitaka; Clough, Timothy J.
• Is Part Of: Grassland science. Volume 61:Number 2(2015:Jun.)
• Page Start: 61
• Page End: 74
• Publication Date: 2015-05-06
• Subjects: Grasslands -- Periodicals; Grasslands -- Management -- Periodicals; 578.74
• DOI: 10.1111/grs.12093
• Languages: English
• ISSNs: 1744-6961

Abstract

<abstract abstract-type="main" id="grs12093-abs-0001"> <title>Abstract</title> <p>Grazed pastures contribute significantly to the global nitrous oxide (N<sub>2</sub>O) budget. In grazed pastures, the highest N<sub>2</sub>O emission rates are often reported during winter when soils are wet. This review discusses the current knowledge about factors controlling winter N<sub>2</sub>O emissions in grazed pastures. High N<sub>2</sub>O emissions from pastures during winter are also observed from winter‐housed animal feeding systems. At near‐zero temperature, N<sub>2</sub>O producing microbial activity is limited but some soil microbial communities adjust to low temperature better than others. Soil microbiological studies focusing on the identification of cold‐tolerant denitrifiers and/or changes in microbial community structures under cold conditions are required. In winter‐grazed pastures, the availability of substrates, such as nitrate (<inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgjqk77xdk" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:17446961:media:grs12093:grs12093-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>NO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula>) and labile organic carbon (C), for soil microbes producing N<sub>2</sub>O is influenced by factors such as animal wintering system, effluent management systems and plant activity. When animals are housed, N<sub>2</sub>O emissions during the winter storage of manures and the emissions after their application are important contributors to N<sub>2</sub>O inventories. The activity of pasture during winter and its relationship to N<sub>2</sub>O emissions requires further study in order to understand the competition between plants and N<sub>2</sub>O producing microbes for nitrogen, and the role of root exudation. Additionally, the effect of low temperatures on nutrient availability under urine patches is still not well known. The reduction of N<sub>2</sub>O to dinitrogen is regulated by an enzyme N<sub>2</sub>O reductase and its encoding gene (<italic>nosZ</italic>) expression needs to be studied in more detail to investigate the mechanisms behind winter N<sub>2</sub>O emissions. To mitigate N<sub>2</sub>O emissions during winter, restricted grazing regimes and the use of nitrification inhibitors have been studied; however, little is known about the effectiveness of these methods in mitigating N<sub>2</sub>O emissions during freeze/thaw cycles and during periods of snow‐cover.</p> </abstract>