ISSN 1058-3912
Electronic journal of the International Association
for Environmental Hydrology
On the World Wide Web at http://www.hydroweb.com
JEH Volume 6 (1998), Paper 8, August 1998
Posted August 8, 1998
NITROUS OXIDE FLUXES FROM A CLAYPAN SOIL OVERLYING NITRATE-ENRICHED
GLACIAL DRIFT
M.L. Pomes, D.H. Wilkison, and P.B. McMahon
U.S. Geological Survey, Water Resources Division, Independence, Missouri,
USA
ABSTRACT
The closed chamber method was used to assess nitrous oxide (N2O)
fluxes from corn (Zea mays, L.) fields during the 1995 growing season.
The study area was characterized by a claypan soil overlying a nitrate
(NO31- )-enriched glacial-drift aquifer. Denitrification
produced N2O fluxes of 0.2-6.9 g ha-1 hr-1
early in the growing season. Fluxes increased with increasing soil temperature,
soil water potential, and soil saturation. However, greatly diminished
N2O fluxes (0.001-0.09 g ha-1 hr-1 ) occurred
when soil saturation increased to 94 percent. Losses of N2O
increased linearly during the day and decreased at night, probably because
of declining soil temperatures. Declines in soil saturation (less than
80 percent) and soil moisture potential (less than -10 kPa) produced late
season N2O fluxes (0.03-0.8 g ha-1 hr-1
) attributable to nitrification. Results indicate that denitrification
would not significantly reduce claypan soil NO31- concentrations.
Reference: Pomes, M.L. , D.H. Wilkison, and P.B. McMahon; Nitrous
Oxide Fluxes From a Claypan Soil Overlying Nitrate-Enriched Glacial Drift,
Journal of Environmental Hydrology, Vol. 6, Paper 8, August 1998.
Donald H. Wilkison
U.S. Geological Survey - WRD
301 W. Lexington, Room 223
Independence, Missouri 64050
USA
e-mail:wilkison@usgs.gov