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Title: MITIGATING NET GLOBAL WARMING POTENTIAL (CO2, CH4 AND N2O) IN UPLAND CROP PRODUCTIONS

Author
item MOSIER, ARVIN
item PETERSON, G - COLO STATE UNIV
item SHERROD, LUCRETIA

Submitted to: Methane and Nitrous Oxide International Workshop Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/30/2003
Publication Date: 11/17/2003
Citation: Mosier, A.R., Peterson, G.A., Sherrod, L.A. 2003. Mitigating net global warming potential (CO2, CH4 and N2O) in upland crop productions. Methane and Nitrous Oxide International Workshop Proceedings, Nov. 17-21-2003, Beijing, China. p. 273-280..

Interpretive Summary: Agricultural soils are sources and sinks for atmospheric greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Storage of atmospheric CO2 into stable organic fractions in the soil can remove CO2 from the atmosphere while normal crop production practices generate N2O and decrease the soil sink for atmospheric CH4 in upland soils. The overall balance between the net exchange of these gases constitutes the net global warming potential (GWP) of a crop production system. In upland cropping systems changes in soil organic matter content, the CO2 emitted from fertilizer production, transport and application, and N2O emissions are the major components of net GWP. The total 'greenhouse effect' in a cropping system needs to be considered in developing new management systems to limit net GWP while maintaining crop production, and not just single components independently. A number of management concepts are currently available that meet this criteria.

Technical Abstract: When appraising the impact of food and fiber production systems on composition of earths atmosphere, the entire suite of greenhouse gases [carbon dioxide (CO2) methane (CH4) and nitrous oxide (N2O)] needs to be considered. Storage of atmospheric CO2 into stable organic fractions in the soil can sequester CO2 while normal crop production practices generate N2O and decrease the soil sink for atmospheric CH4 in upland soils. The overall balance between the net exchange of these gases constitutes the net global warming potential (GWP) of a crop production system. In upland cropping systems changes in soil organic matter content, the CO2 emitted from fertilizer production, transport and application, and N2O emissions are the major components of net GWP. Managing upland agricultural systems to optimize soil C storage and minimize N2O can have a significant impact on the future atmospheric radiative forcing resulting from CO2 and N2O in the atmosphere as well as sustainable intensive crop production. Soil C levels have been increased by reducing tillage intensity, increasing intensity of crop rotations, and with N fertilization. Nitrogen fertilization is essential to maintaining crop yields and economic sustainability, but excessive N application increases N2O emissions which can more than offset gains in C storage. If we are to develop crop management systems that will decrease net GWP in the future, these systems will also need to maintain crop production and improve soil quality. The effect of management options that are currently available, such as tillage, control release fertilizers and nitrification inhibitors on N2O emissions and net GWP are discussed.