Nitrous oxide, methane emission, and yield-scaled emission from organically and conventionally managed systems

Empirical data on methane (CH4) and nitrous oxide (N2O) emission are needed for management systems from many regions of the United States to evaluate mitigation strategies. The primary objectives of this study were to assess and compare crop productivity, CH(4) andN(2)O flux, and yield-scaled emissi...

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Bibliographic Details
Published in:Soil Science Society of America journal 2012-07, Vol.76 (4), p.1347-1357
Main Authors: Johnson, Jane M.F, Weyers, Sharon L, Archer, David W, Barbour, Nancy W
Format: Article
Language:English
Subjects:
Agricultural commodities
Agronomy. Soil science and plant productions
alfalfa
Biological and medical sciences
Carbon dioxide
Climate change
corn
crop production
Dogs
Earth sciences
Earth, ocean, space
Emissions
Exact sciences and technology
fertilizer application
Fundamental and applied biological sciences. Psychology
GDP
Glycine max
greenhouse gas emissions
Greenhouse gases
Gross Domestic Product
growing season
Manures
Medicago sativa
methane
methane production
Microclimate
nitrous oxide
organic production
Precipitation
Soil erosion
Soil fertility
Soil science
Soils
Surficial geology
traditional farming
Triticum aestivum
Zea mays
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Summary:Empirical data on methane (CH4) and nitrous oxide (N2O) emission are needed for management systems from many regions of the United States to evaluate mitigation strategies. The primary objectives of this study were to assess and compare crop productivity, CH(4) andN(2)O flux, and yield-scaled emissions between a conventionally and an organically managed system. All phases of a corn (Zea mays L.)–soybean [Glycine max L. (Merr.)]–wheat (Triticum aestivum L.) over alfalfa (Medicago sativa L.)–alfalfa rotation were present each year. Both systems emitted about 4.2 kg N(2)O-N ha(−1) yr(−1) including growing and nongrowing season emissions, which cumulatively represents 4.74 and 9.26% of 267 kg synthetic-N and 136 kg manure-N applied, respectively. The equivalent of 0.84% of the 78 kg urea-N and 0.76% of the 136 kg manure-N were emitted as N(2)O ha(−1) within 30-d of fertilizer application in the conventionally managed system and organically managed system, respectively. Following the application of starter fertilizer to the conventionally managed corn, the equivalent of 3.45% of the 11 kg starter N was emitted within 30 d. The largest spring-thaw N(2)O flux was measured in the conventionally managed system following alfalfa, which had been killed the previous fall. Yield-scaled N(2)O+CH(4) emission (Mg CO(2) equivalents Mg(−)1 yield) was 1.6- to 5-times greater in the organically managed system, which had lower yield but similar emission compared to the conventionally managed system. Thus, viability of organic systems to mitigate greenhouse gas (GHG) emission may be compromised when crop productivity is reduced. Study results highlight the importance of assessing emission and crop production when evaluating GHG mitigation strategies.
ISSN:0361-5995
1435-0661
DOI:10.2136/sssaj2012.0017