Boundary line analysis of the effect of water-filled pore space on nitrous oxide emission from cores of arable soil

Nitrous oxide (N2O) produced from agricultural activities represents a threat to the ozone layer and economic losses. Rates and magnitudes of N2O emissions of cropping systems must be determined to establish corrective management procedures. In 1994, N2O emissions were determined with corn (ZeaMays L.) and corn-legume rotations. Continuous corn was studied on four soils, two from a long-term experiment, a Ste. Rosalie heavy clay (Humic Gleysol) and a Chicot sandy loam (Grey-Brown Podzol), at 0, 170, 285 or 400 kg N ha−1, and two from a corn rotation study, a Ste. Rosalie clay (Humic Gleysol) and an Ormstown silty clay loam (Humic Gleysol). Treatments included no-till (NT) and conventional tillage (CT), monoculture corn (CCCC), monoculture soybean; corn-soybean; and soybean-corn-alfalfa phased rotations. Nitrogen rates of 0, 90, or 180 kg N ha−1 for corn and 0, 20, or 40 kg N ha−1 for continuous soybean were used, and soybean/alfalfa following corn no fertilizer N. Rates of N2O emission were measured from closed chambers through the growing season. About 0.99 to 2.1% of N added was lost as N2O. Nitrous oxide emission increased with increased soil water content, NO3 concentration and fertilizer N rates. Emission of N2O was higher with NT than with CT, and with corn than with soybean or alfalfa. A corn system using CT, legumes in rotation and moderate fertilizer N would reduce N2O emission. Key words: Greenhouse gases, soil nitrate, tillage methods, water-filled pore space, denitrification, rotations

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Understanding the hydrologic control of N cycle: Effect of water filled pore space on heterotrophic nitrification, denitrification and dissimilatory nitrate reduction to ammonium mechanisms in unsaturated soils

Journal of Contaminant Hydrology ◽

10.1016/j.jconhyd.2017.04.005 ◽

2017 ◽

Vol 202 ◽

pp. 11-22 ◽

Cited By ~ 8

Author(s):

C. Mekala ◽

Indumathi M. Nambi

Keyword(s):

Nitrate Reduction ◽

Unsaturated Soils ◽

Pore Space ◽

Heterotrophic Nitrification ◽

N Cycle ◽

Effect Of Water ◽

Dissimilatory Nitrate Reduction ◽

Water Filled Pore Space

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Hydrological controls on denitrification in riparian ecosystems

Hydrology and Earth System Sciences ◽

10.5194/hess-8-686-2004 ◽

2004 ◽

Vol 8 (4) ◽

pp. 686-694 ◽

Cited By ~ 29

Author(s):

S. E. Machefert ◽

N. B. Dise

Keyword(s):

Nitrous Oxide ◽

Soil Moisture ◽

Pore Space ◽

Denitrification Rate ◽

Riparian Ecosystems ◽

Exponential Relationship ◽

Wide Range ◽

Water Filled Pore Space ◽

The Uk

Abstract. Nitrous oxide fluxes and denitrification rates were measured in situ over a year at a riparian site in the UK. An exponential relationship was found between denitrification rates and soil moisture, with a sharp increase in denitrification rate at a water-filled pore space of 60–80%. Similar relationships were found in other studies compiled for comparison. The present study is unique in measuring denitrification in an "intact" ecosystem in the field, rather than in cores in the field or the lab. The exponential relationship between denitrification rate and soil moisture, with a "threshold" at 60–80% water-filled pore space (20–40% gravimetric moisture), has proven to be comparable across a wide range of ecosystems, treatments and study conditions. Whereas moisture content determines the potential for denitrification, the absolute rate of denitrification is determined by available nitrate (NO3-), dissolved organic carbon and temperature. As a first approximation, denitrification rates can be simply modelled by using a general exponential relationship between denitrification potential and water-filled pore space (or volumetric/gravimetric water content) multiplied by a constant value determined by the nitrogen status of the site. As such, it is recommended that the current relationship used in INCA to relate denitrification to soil moisture be amended to an exponential form, with a threshold of approximately 70% for the onset of denitrification. Keywords: nitrous oxide, denitrification, soil moisture, nitrogen, eutrophication, riparian

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