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United States Department of Agriculture

Agricultural Research Service

Title: Fertilizer induced losses of nitrous oxide gas from Montana dryland cropping systems

Authors
item Engel, Richard - MONTANA STATE UNIVERSITY
item SAINJU, UPENDRA

Submitted to: Meeting Abstract
Publication Type: Other
Publication Acceptance Date: January 30, 2007
Publication Date: February 1, 2007
Citation: Engel, R., Sainju, U.M. 2007. Fertilizer induced losses of nitrous oxide gas from Montana dryland cropping systems. Fertilizer Advisory Committee Progress Report-2006.

Interpretive Summary: Nitrous oxide (N2O) is one of the potentially devastating greenhouse gases that has 300 times greater global warming potential than CO2. Agricultural practices contribute about 73% of the total N2O emission, primarily from N fertilization to crops to increase yields. Little is known about N2O emission in dryland cropping systems in the northern Great Plains. A study was conducted to measure soil surface N2O and methane (CH4) fluxes from May to November, 2006 and malt barley yields in a dryland cropping system containing continuous malt barley, malt barley-Austrian winter pea, malt barley-chemical fallow and malt barley-tilled fallow with two N fertilization rates (0 and 80 kg N ha-1) in eastern Montana. Increased N2O flux was observed in the N fertilized treatments compared with no N fertilization at 4 wk after N fertilization and at 14 wk following a heavy rainfall, probably a result of increased N availability and microbial activities. Nitrogen loss as N2O emission from applied N fertilizer accounted for 0.11%, a values 10 times lower than predicted by Intergovernmental Panel on Climate Change (IPCC). Cropping system did not influence N2O flux. Similarly, cropping system and N fertilization did not influence CH4 flux. However, CH4 flux was lower than the ambient air level from June to November, suggesting the sinking capacity of soil for CH4 in the summer and autumn. Malt barley yield was higher with N fertilization than without and higher with Austrian winter pea-malt barley than in other cropping systems. The N2O emission is especially linked with N fertilization and organic matter mineralization because emission increased a few weeks after fertilization and rainfall, regardless of the cropping system in the dryland. The N2O flux predicted by IPCC needs to be revised, especially for the semi-arid dryland cropping system. Since the study was carried out during crop growing season in the summer and early fall, more information is needed to evaluate the effects of cropping system, N fertilization, and environmental conditions on N2O emission by measuring fluxes in a number of years.

Technical Abstract: Nitrogen fertilization to crops contributes a significant portion of soil nitrous oxide (N2O) emission, a greenhouse gas responsible for global warming. This information is, however, lacking in the dryland cropping system in the northern Great Plains. Soil N2O and methane (CH4) fluxes from May to November, 2006 and malt barley yields were measured in a dryland cropping system containing continuous malt barley, malt barley-Austrian winter pea, malt barley-chemical fallow and malt barley-tilled fallow with two N fertilization rates (0 and 80 kg N ha-1) in eastern Montana. Increased N2O flux was observed in the N fertilized treatments compared with no N fertilization at 4 wk after N fertilization and at 14 wk following a heavy rainfall, probably a result of increased N availability and microbial activities. Nitrogen loss as N2O emission from applied N fertilizer accounted for 0.11%, a values 10 times lower than predicted by Intergovernmental Panel on Climate Change (IPCC). Cropping system did not influence N2O flux. Similarly, cropping system and N fertilization did not influence CH4 flux. However, CH4 flux was lower than the ambient air level from June to November, suggesting the sinking capacity of soil for CH4 in the summer and autumn. Malt barley yield was higher with N fertilization than without and higher with Austrian winter pea-malt barley than in other cropping systems. Nitrogen fertilization increased malt barley yield and N2O flux in the summer and autumn, regardless of the cropping system, and that the flux predicted by IPCC needs to be revised, especially for the semi-arid dryland cropping system.

Last Modified: 7/25/2014
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