Author
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Allen Jr, Leon |
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Submitted to: Book Chapter
Publication Type: Book / Chapter Publication Acceptance Date: 2/16/2012 Publication Date: 6/8/2012 Citation: Allen Jr, L.H. 2012. Greenhouse gas fluxes of drained organic and flooded mineral agricultural soils in the United States. In: Liebig, M.A., Frazluebbers, A.J., Follet, R.F. Managing agricultural greenhouse gases. First Edition. San Diego, California: Elsevier. 221-238. Interpretive Summary: ARS research is seeking ways to reduce the impact of agriculture on greenhouse gas emissions by fostering practices that promote carbon sequestration or decrease the emissions of greenhouse gases. This research is expected to help alleviate the problem of greenhouse gases on global warming. An ARS scientist at Gainesville, Florida provided a chapter entitled “Greenhouse Gas Fluxes of Drained Organic and Flooded Mineral Agricultural Soils in the United States” for a book entitled “Managing Agricultural Greenhouse Gases” produced largely by a team of ARS GRACEnet scientists. Although drained organic soils and flooded mineral soils each represent only about 1% of US cropland plus grazing lands, they (especially drained organic soils) emit greenhouse gases that currently offset about 40% of the reduction in greenhouse warming potential of carbon sequestration that can be achieved by good management practices of the other 98%. However, this chapter also pointed out that use of crop cultivars adapted for high water tables would reduce carbon dioxide emissions of organic soils. Moreover, adoption of appropriate management practices can reduce emissions of methane and nitrous oxide from flooded rice soils. Most work on assessing the impact of drained organic soils has been conducted in northern Europe and tropical southeastern Asia. Also, findings regarding greenhouse gas reductions in US rice culture have been confirmed many times in Asia. Finally, eddy covariance for measuring gas fluxes continuously, along with flux-pan techniques, could be used to confirm efficacy of emissions reduction practices. Technical Abstract: Drained organic soils for agriculture represent less than 1% of the area used for crops in the United States (US). However, emission of carbon dioxide (CO2) from microbial oxidation of drained organic soils offsets almost half of the contributions that carbon sequestration of other cropping systems make to reductions in global warming potential (GWP). Nitrous oxide (N2O) emissions from drained organic soils also contribute to offsetting part of the favorable greenhouse gas (GHG) balance of other cropping systems. Growth of adaptable crops on organic soils using shallow water tables could substantially reduce their GHG emissions. Research has shown that sugarcane (Saccharum officinarum L.) can sustain yields in managed, shallow water tables and periodic flooding on organic soils. Flooded rice (Oryza sativa L.) also represents a small fraction of lands used for agriculture on mineral soils in the US, but this land use can cause large emissions of methane (CH4). Reducing the incorporation of crop residues into the soil and managed applications of nitrogen along with periodic drawdown of the water table are potential management practices for rice production in flooded fields to reduce CH4 emissions while minimizing releases of N2O. Continuous eddy covariance measurements of CO2, CH4, and N2O fluxes, in conjunction with other flux measurements, would provide verification of the effectiveness of management strategies for reducing the impact of agriculture on GHG emissions. |
