|Sparrow, Elena - ARS|
|Schlentner, Sharon - ARS|
|Knight, Charles - UNIVERISTY OF ALASKA|
Submitted to: Canadian Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 23, 1997
Publication Date: N/A
Interpretive Summary: Methane and nitrous oxide gas concentrations in the atmosphere are increasing. These two gasses are also contributing to global warming. Agricultural practices influence the production and/or consumption of these gasses. This study assesses the long-term effect of conventional tillage and no-tillage. The removal of barley straw, and nitrogen fertilizer rate on the fate of these two gasses in soil. Some soil microorganisms consume methane and continued usage of no tillage increased the total consumption of methane over the summer. Maintaining straw on the soil also had higher consumption than where it was removed. The use of nitrogen fertilizer had little effect on methane consumption. Nitrous oxide was not affected by tillage or crop residue management, but was increased with increases in nitrogen fertilizer, but accounted for less than one percent of that applied. We conclude that conservation tillage practices will increase the consumption of methane while fertilizer practices to obtain high yield will have minimal effects on nitrous oxide production.
Technical Abstract: Methane and nitrous oxide are important radiatively active gases that are influenced by agricultural practices. This study assesses long term tillage, crop residue management, and N fertilization rates on the flux of these two gases at high latitude site on the northern fringe of large scale agriculture. Cumulative methane consumption for the summer was higher from no-tillage plots than tilled plots. This was associated with low soil wate contents with tillage. The reduction in CH-4 consumption was attributed to water stress on methane oxidizers. At planting, no-till plots had the highest water contents and the lowest consumption due to restricted diffusion of methane to active sites. A similar pattern of methane consumption to soil water content was found with the residue management treatments. Removing the straw lowered the soil water content and for most of the season methane consumption was also lower than where the straw was left on the plots. Nitrogen fertilizer rate had little effect on methane consumption over the summer, but high N rates lowered consumption during the time of active nitrification early in the season. This corresponded to the time of maximum efflux of nitrous oxide. Nitrous oxide efflux was greatest at the high N rate where straw was retained on the plots.