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Title: Nitrogen, Tillage, and Crop Rotation Effects on Nitrous Oxide Emissions from Irrigated Cropping Systems.

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

Submitted to: USDA Greenhouse Gas Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2006
Publication Date: 2/5/2007
Citation: Halvorson, A.D., Del Grosso, S.J. 2007. Nitrogen, Tillage, and Crop Rotation Effects on Nitrous Oxide Emissions from Irrigated Cropping Systems. USDA Greenhouse Gas Symposium. In Abstracts of 4th USDA Symposium on Greenhouse Gases and Carbon Sequestration in Agriculture and Forestry. Feb. 6-8, 2007, Baltimore, MD.

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 several irrigated cropping system plots 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); Strip-till CC (ST-CC); NT corn-dry bean (NT-CDb); and NT corn-barley (NT-CB). In 2005, half the N fertilizer rate was subsurface band applied as liquid urea-ammonium nitrate (UAN) at planting to the corn and dry bean plots with the second half of the N rate applied as a surface broadcast polycoated urea (ESN®, environmentally smart nitrogen produced by Agrium Inc.) in mid-June. All of the UAN was applied at planting on the NT-CB barley plots in 2005. All plots were planted to corn in 2006, with ESN being applied at half the N rate at corn emergence and a second N application as dry urea about the V6-V7 corn growth stage, both banded on the soil surface in the corn row followed by irrigation. N2O fluxes were measured from each treatment two to three times weekly from planting until crop harvest using static, vented chambers and gas chromatograph analyzer. N2O emissions were generally greater from the NT-CDb system than the other cropping systems. Tillage system had little effect on N2O emissions. N2O emissions increased linearly with increasing N rate both years. The spikes in N2O emissions following N fertilizer application were much greater with UAN and urea than with ESN® fertilizer. ESN® shows potential for reducing N2O emissions from irrigated cropping systems.