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Title: Some sources of variability in the CO2 enhancement ratio

Author
item Fiscus, Edwin
item REID, CHANTAL - DUKE UNIVERSITY
item Booker, Fitzgerald

Submitted to: USDA Greenhouse Gas Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2007
Publication Date: 2/20/2007
Citation: Fiscus, E.L., Reid, C.D., Booker, F.L. 2007. Some sources of variability in the CO2 enhancement ratio. USDA Greenhouse Gas Symposium.

Interpretive Summary: All other things being equal, elevated atmospheric CO2 levels have the potential to increase crop yields. However there is a wide range of variability associated with the potential increases with experimental results ranging from substantial negative values to large (30-50%) increases in productivity as a result of experimental increases in CO2. It is the purpose of this paper to demonstrate how environmental variables such as temperature, drought, air pollutants and soil nutrition might affect the potential productivity increases due to elevated CO2 and to explore how certain mangement practices might optimize the productivity returns in future climates.

Technical Abstract: Recent meta-analyses and compilations of past experiments show a wide range of crop productivity responses to elevated atmospheric [CO2]. Variances, even within the same protocols, can be quite large ranging from less than 1 to greater than 30 times for [CO2] about double the current atmospheric mean. Among the variables known to affect the CO2 enhancement ratio (CER) are air pollutants, drought, plant competition, temperatures and soil nutrition. It is the purpose of this presentation to explore the effects and interactions of some of these factors to determine if there are practical methods of stabilizing the variability of response and/or maximizing the enhancement potential of elevated [CO2].