HR: 1330h
AN: B32B-0378    [PDF]
TI: Impact of Tillage, Crop Sequence and N-fertilization on Trace Gas Exchange in an Irrigated Agroecosystem in Northeastern Colorado
AU: * Mosier, A R
EM: amosier@lamar.colostate.edu
AF: USDA/ARS, 301 S. Howes P.O. Box E, Fort Collins, CO 80522
AU: Halvorson, A D
EM: adhalvor@lamar.colostate.edu
AF: USDA/ARS, 301 S. Howes P.O. Box E, Fort Collins, CO 80522
AB: A long-term study was initiated in 1999 to investigate the potential of no-till cropping systems to sequester CO2 while maintaining crop production in irrigated agriculture in northeastern Colorado. As the impact of agricultural management changes on trace gas fluxes are not well understood, we began measuring the soil-atmosphere exchange of CO2, CH4 and N2O during the spring of 2002. Fluxes were measured, using vented chambers, one to three times per week, year round, within plots that are continuously cropped to corn under conventional plow tillage (CT), within no-till continuous corn plots (NT), and within a NT corn-soybean rotation. Plots were fertilized at planting with rates of 0, 134 and 202 kg N ha-1. In 2002, all plots in which trace gas fluxes were measured were cropped with corn that was planted on April 26 and harvested on November 5, 2002. From planting until early April 2003 no tillage or N-fertilization effects on CH4 flux were observed, with the soil serving as a small CH4 source during the irrigation season and a small sink during the winter. Converting to NT did not increase N2O emissions while N2O emissions increased in response to fertilizer N supply. N2O emissions were higher in plots that had been cropped to soybeans the year before. On January 2, 2003 the CT plots were plowed. Even though soil temperature was near zero oC, CO2 fluxes averaged 33+/-5 mg C m-2 hr-1 in CT plots compared to 4.8+/-1.4 in NT plots the day after plowing. The first year of trace gas flux measurements suggest that converting conventionally plowed soils to no-till decreases soil CO2 loss and does not increase N2O or CH4 flux.
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
DE: 1600 GLOBAL CHANGE (New category)
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting