Fluxes of carbon dioxide, nitrous oxide, and methane in grass sod and winter wheat-fallow tillage management
- Univ. of Nebraska, Lincoln, NE (United States). Dept. of Agronomy
- Dept. of Agriculture, Fort Collins, CO (United States)
- Dept. of Agriculture, Lincoln, NE (United States)
- Panhandle Research and Extension Center, Scottsbluff, NE (United States)
- FAL, Braunschweig (Germany)
Cropping and tillage management can increase atmospheric CO{sub 2}, N{sub 2}O, and CH{sub 4} concentrations, and contribute to global warming and destruction of the ozone layer. Fluxes of these gases in vented surface chambers, and water-filled pore space (WFPS) and temperature of surface soil were measured weekly from a long-term winter wheat (Triticum aestivum L.)-fallow rotation system under chemical and mechanical tillage follow management and compared with those from native grass sod at Sidney, NE, from March 1993 to July 1995. Cropping, tillage, within-field location, time of year, soil temperature, and WFPS influenced net greenhouse gas fluxes. Mean annual interrow CO{sub 2} emissions from wheat-fallow ranged from 6.0 to 20.1 kg C ha{sup {minus}1} d{sup {minus}1} and generally increased with intensity and degree of tillage. Nitrous oxide flux averaged < 1.2 g N ha{sup {minus}1} d{sup {minus}1} for sod and 1 to 2 g N ha{sup {minus}1} d{sup {minus}1} for wheat-fallow. Tillage during fallow increased N{sub 2}O flux by almost 100%. Nitrous oxide emissions were 1.5 to 3.7 times greater from crop row than interrow locations with greatest differences occurring during periods of highest N{sub 2}O emission. Mean annual N{sub 2}O flux over the 3 yr of study were 1.54 and 0.76 g N ha{sup {minus}1} d{sup {minus}1} for row and interrow locations. Methane uptake ranged from 5.9 to 9.9 g C ha{sup {minus}1} d{sup {minus}1} and was not influenced by row location. Seasonal CO{sub 2} and N{sub 2}O flux, and CH{sub 4} uptake ranked as spring {ge} summer > autumn > winter. Winter periods accounted for 4 to 10% and 3 to 47% of the annual CO{sub 2} and N{sub 2}O flux, respectively, and 12 to 21% of the annual CH{sub 4} uptake. Fluxes of CO{sub 2} and N{sub 2}O, and CH{sub 4} uptake increased linearly with soil temperature. No-till fallow exhibited the least threat to deterioration of atmospheric or soil quality as reflected by greater CH{sub 4} uptake, decreased N{sub 2}O and CO{sub w} emissions, and less loss of soil organic C than tilled soils. However, potential for increased C sequestration in this wheat-fallow system is limited due to reduced C input from intermittent cropping.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 290129
- Journal Information:
- Journal of Environmental Quality, Vol. 27, Issue 5; Other Information: PBD: Sep-Oct 1998
- Country of Publication:
- United States
- Language:
- English
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