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Title: Elevated CO2 and warming effects on soil carbon sequestration and greenhouse gas exchange in agroecosystems: A review

item Dijkstra, Feike
item Morgan, Jack

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 11/1/2011
Publication Date: 12/15/2011
Citation: Dijkstra, F.A., Morgan, J.A. 2011. Elevated CO2 and warming effects on soil carbon sequestration and greenhouse gas exchange in agroecosystems: A review. In: L.R. Ahuja, L. Ma (eds). Methods of introducing system models into agricultural research. Madison, WI: ASA/CSSA/SSSA. pp. 267-486.

Interpretive Summary:

Technical Abstract: Concentrations of CO2 and other greenhouse gases (GHGs) have been increasing dramatically in earth’s atmosphere since the industrial revolution, and are expected to continue increasing from ~385 ppmv today to more than 600 ppmv by the end of this century. Global surface temperatures are expected to rise between 1.1 to 5.4°C by 2100, depending on how fast greenhouse gas concentrations increase. Precipitation dynamics are also predicted to change, although there is still considerable uncertainty in these projections. While some of the details of these events are unclear, most agree climate change has already affected agroecosystems worldwide, and will have even more profound effects as climate change accelerates. This review addresses the effects of warming and rising CO2 on the GHG balance. We found that elevated CO2 had the potential to increase soil C, particularly in combination with N fertilization. However, we also found that the increase in soil C in combination with N fertilization did not come without a price. N2O emissions also increased under elevated CO2 with N fertilization, and indeed on average the CO2-induced increase in N2O emission in terms of its Global Warming Potential more than offset the average increase in soil C in N fertilized studies. Thus, particularly in N fertilized agroecosystems, one can come to the wrong conclusion about the effect of elevated CO2 on the GHG balance expressed in CO2 equivalents if N2 O emissions are not accounted for. More research is needed to determine how and under what conditions practices like precision application of N fertilizer, the use of nitrification inhibitors, and the use of legumes and forage grasses might help capitalize on the potential for rising CO2 to enhance C sequestration.