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Title: Landscape scale estimation of denitrification rate and nitrous oxide to dinitrogen ratio at Georgia and Pennsylvania sites

item Dell, Curtis
item GROFFMAN, PETER - Cary Institute Of Economic Studies
item Strickland, Timothy - Tim
item Kleinman, Peter
item Bosch, David - Dave
item Bryant, Ray

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 10/15/2015
Publication Date: 12/5/2015
Citation: Dell, C.J., Groffman, P., Strickland, T.C., Kleinman, P.J., Bosch, D.D., Bryant, R.B. 2015. Landscape scale estimation of denitrification rate and nitrous oxide to dinitrogen ratio at Georgia and Pennsylvania sites[Abstract]. American Geophysical Union Fall 2015 Meeting. Paper No H51Q-05.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: Denitrification results in a significant loss of plant-available nitrogen from agricultural systems and contributes to climate change, due to the emissions of both the potent greenhouse gas nitrous oxide and environmentally benign dinitrogen. However total quantities of the gases emitted and the ratio of nitrous oxide to dinitrogen are often not clearly understood, because N2 emissions cannot be directly measured in the field because of the high background level of N2 in the atmosphere. While variability in soil conditions across landscapes, especially water content and aeration, is believed to greatly impact both total denitrification rates and nitrous oxide to dinitrogen, the measurement limitations have prevented a clear understanding of landscape-scale emissions of denitrification products. The Cary Institute has developed an approach where soil core are maintained in a sealed system with a dinitrogen -free airstream, allowing emitted dinitrogen and nitrous oxide emissions to be measured without interference from atmospheric dinitrogen. Emissions of the gases are measured under a range of oxygen concentrations and soil water contents. Laboratory responses can then be correlated with measured field conditions at the sampling points and resulting emission estimates extrapolated to the field-scale. Measurements are currently being conducted on peanut/cotton rotations, dairy forage rotations (silage corn/alfalfa), and bioenergy crops (switchgrass and miscanthus) at Long Term Agricultural Research (LTAR) sites at Tifton, GA and University Park, PA.