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Title: Nitrous Oxide Emissions from Irrigated Cropping Systems in Colorado

Author
item Halvorson, Ardell
item Del Grosso, Stephen - Steve
item Reule, Curtis

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/20/2007
Publication Date: 11/4/2007
Citation: Halvorson, A.D., Del Grosso, S.J., Reule, C.A. 2007. Nitrous Oxide Emissions from Irrigated Cropping Systems in Colorado. ASA-CSSA-SSSA Annual Meeting Abstracts. CD-ROM.

Interpretive Summary:

Technical Abstract: Little information is available on the effects of irrigated crop management practices on nitrous oxide (N2O) emissions. Nitrous oxide emissions were monitored from irrigated cropping systems receiving N fertilizer rates ranging from 0 to 246 kg N ha-1 during the 2005 and 2006 growing seasons. Cropping systems included: conventional-till (CT) continuous corn (CC) (CT-CC); no-till (NT) CC (NT-CC); NT corn-dry bean (NT-CDb); and NT corn-barley (NT-CB). In 2005, half the N fertilizer rate was applied as urea-ammonium nitrate (UAN) at planting to the corn plots with the second half of the N rate applied as a surface broadcast polycoated urea (ESN®) in mid-June. All N was applied as UAN at planting on the NT-CB barley and NT-CDb dry bean plots in 2005. All plots were in corn in 2006, with ESN® being applied at half the N rate at corn emergence and half as dry urea about the V6-V7 corn growth stage, both surface banded in the corn row followed by irrigation. Fluxes of N2O were measured from planting until crop harvest using static, vented chambers, one to three times per week, and a gas chromatograph analyzer. Growing season N2O emissions increased linearly with increasing N-fertilizer rate each year in all cropping systems, but emission amounts varied with years. Growing season N2O emissions were generally greater from the NT-CDb system during the corn phase of the rotation than from the other cropping systems. Crop rotation and N fertilization rate had more effect than tillage system on N2O emissions. The amount of N2O emitted from N fertilizer application ranged from 0.30 to 0.75% of N applied. Spikes in N2O emissions following N fertilizer application were much greater with UAN and urea than with ESN® fertilizer. ESN® showed potential for reducing N2O emissions from irrigated cropping systems. [GRACENet Publication].