February 28, 2007
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FROM VOLUME 5, NUMBER 9, SEPTEMBER 1992
CHEMICAL CYCLES: N2O EMISSIONS FROM SOILS
"Modelling the Exchange of Nitrogen Oxides between Soils and the
Atmosphere," J. Arah (Edinburgh Sch. Agric., Scottish Agric. Coll., West
Mains Rd., Edinburgh EH9 3JG, Scotland), Chem. & Industry, No. 14, 530-532,
July 20, 1992.
Reviews the status of both microsite and regression approaches to modeling,
and problems that must be overcome to be able to extrapolate model results to
"A Model of Nitrous Oxide Evolution from Soil Driven by Rainfall
Events," C. Li (Bruce Co., 1100 6th St. NW, S. 215, Washington DC 20024),
S. Frolking, T.A. Frolking, J. Geophys. Res., 97(D9), June 20,
"1. Model Structure and Sensitivity," 9759-9776. Simulations using
a process-oriented model show that between rainfall events, the decomposition of
organic matter and other oxidation reactions dominate; during rainfall,
denitrification dominates and produces N2O and N2. During a one-year sensitivity
simulation, variations in temperature, precipitation, organic C, clay content
and pH had significant effects on calculated N2O emissions.
"2. Model Applications," 9777-9783. Model
simulations were compared with five field studies in Europe and North America.
The trends and magnitude of simulated N2O emissions were consistent, showing the
model to be a useful tool for studying linkages among climate, land use,
soil-atmosphere interactions, and trace gas fluxes.
"NO Versus N2O Emissions from an NH4+-Amended Bermuda Grass Pasture,"
G.L. Hutchinson (USDA-ARS, POB E, Fort Collins CO 80522), E.A. Brams, J.
Geophys. Res., 97(D9), 9889-9896, June 20, 1992.
Emissions were monitored during early summer regrowth of grass in southern
Texas using an enclosure technique. Emissions were higher from
plots harvested at the beginning of the experiment and fertilized five days
later than from unmanaged plots, indicating that humid, subtropical grasslands,
which not only have a large geographical extent but also have been subject to
intense anthropogenic disturbance, contribute significantly to the global NOx
Two items from Soil Sci. Soc. Am. J., 56(3), May-June 1992:
"Landscape-Scale Variations in Denitrification," D.J. Pennock
(Dept. Soil Sci., Univ. Saskatchewan, Saskatoon, Saskatchewan S7N 0W0, Can.), C.
van Kessel et al., 770-776. Measurements made on a 110-meter-square
plot show that topography has a strong influence over in situ denitrification,
different controls are at work in various landform elements, and landscape
analysis should be incorporated in the process of modeling total N losses
"Nitric Oxide and Nitrous Oxide Production from Soil: Water and
Oxygen Effects," C.F. Drury (Res. Sta., Agric. Can., Harrow, Ont. N0R 1G0,
Can.), D.J. McKenney, W.I. Findlay, 766-770. Used a gas-flow column approach
to study the physical effects of water on NO and uN2O production under
conditions favoring denitrification. The Relative amount of N2 production increased with increasing water content.
"Regional Scale Analysis of Denitrifcation in North Temperate Forest Soils," P.M. Groffman (Dept. Nat. Resour., Univ. Rhode Island, Kington RI 02881), J.M. Tiedje et al., Landscape Ecol., 7(1), 45-53, Apr. 1992.
Regional-scale estimates of denitrification from forest soils in southern Michigan were produced by stratifying the region into landscape experimental units using soil texture and natural drainage classes, and extrapolating data to larger areas using a geographic information system.
"Sources of Nitric Oxide and Nitrous Oxide Following Wetting of Dry Soil," E.A. Davidson (Woods Hole Res. Ctr., POB 296, Woods Hole MA 02543), Soil Sci Soc. Amer. J., 56(1) 95-102, Jan.-Feb. 1992. Soil sampled from an annual grassland in California at the end of the dry season was wetted to levels of soil water content above or below field capacity. Production of NO and N2O began immediately. Below field capacity, net production of NO exceeded N2O, while above field capacity N2O exceeded NO. Nitrifying and denitrifying bacteria apparently became active within minutes of wetting.
"Sources of Nitrous Oxide Production Following Wetting of Dry Soil," A.O. Rudaz, (Swiss Fed. Res. Sta., 3097 Liebefeld-Berne, Switz.), E.A. Davidson, M.K. Firestone, FEMS Microbiology Ecology, 85, 117-124, 1991.
Production of N2O was detected within 30 minutes of adding water to very dry soil collected from annual grassland in California. Nitrification was a modest source of N2O in sieved soil wetted below field capacity, but denitrification was the major source of N2O in sieved soils wetted above field capacity and intact cores at all wetness levels. Significant abiological sources of N2O were not detected.
"Annual Nitrous Oxide Flux and Soil Nitrogen Characteristics in Sagebrush Steppe Ecosystems," P.A. Matson (NASA-Ames, Moffet Field CA 94035), C. Volkmann et al., Biogeochem., 14(1), 1-12, 1991.
Soil N transformations and N2O fluxes were measured by laboratory incubation for a range of sagebrush steppe ecosystems in Wyoming. Results lead to a flux estimate for desert and semidesert shrublands of the world of 1.1 x 1011 g yr-1 of N2O-N.
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