Lawrence Sikora, Timothy Griffin, and C. Wayne Honeycutt. USDA-ARS, New England Plant Soil and Water Laboratory, Orono, ME 04469-5753
Estimating global greenhouse gas (GHG) emissions requires regional measurements be made within different production systems. A long-term potato cropping system experiment established in 2004 in Presque Isle, ME, on a sandy loam soil contains three of the systems relevant to the GRACENet Cross-Location Research Project. Included in this experiment are: a) Business as Usual: b) Maximizing Soil C Sequestration: and c) Minimizing Greenhouse Gas (GHG) Emission. Our objective was to compare GHG emissions from these systems during the growing season. The Business as Usual system consists of a barley-potato rotation with fall tillage for both crops. The Soil C Sequestration scenario employs no-till barley with interseeded timothy in Year 1, followed by timothy sod in Year 2, and spring tillage with potato in Year 3. This system is duplicated with an annual compost application. Emissions of carbon dioxide, nitrous oxide, and methane were monitored in the barley phase of each system 14 times during 2006 using aluminum chambers installed in the soil. Significant cropping system effects on carbon dioxide flux were identified on 11 of the first 13 sample dates. Less carbon dioxide was given off from the Business as Usual system than the other two management systems on 6 of the first 7 sample dates; however, the carbon dioxide flux was higher from this system at the end of the season. Five of the 13 sample dates exhibited significant nitrous oxide flux differences due to cropping system. Treatment differences were not consistent between sample dates, possibly because of differences in soil temperature and/or moisture. This research will contribute to national estimates of GHG emissions from agriculture.