Tuesday, November 14, 2006 - 1:15 PM

Microbial and Physical Process Interactions Controlling Nitrous Oxide Emissions.

Rodney Venterea, USDA-ARS, 1991 Upper Buford Circle, 439 Borlaug Hall, St. Paul, MN 55108-6028

A variety of edaphic, climatic, hydrologic, and management variables have been shown to regulate nitrous oxide (N2O) emissions from agricultural soils.  Reactions catalyzed by microbial enzyme systems are the generating and consuming processes which are subject to influence from these other factors.  There are still many aspects of microbial enzyme activity related to N2O production that are poorly understood. While a detailed understanding of all potential N2O-mediating enzyme systems may not be needed for improving nitrogen management, there are some fundamental characteristics of these systems that have important practical implications.  Using a combination of experimental data and gas transport modeling, this paper examines characteristics of N2O -mediating enzyme systems that are currently not well understood. Interactions of these characteristics with management factors can strongly regulate field N2O emissions.  Some of these effects only become evident when gas transport processes are considered together with microbial dynamics.  Our ability to incorporate such factors and interactions into effective predictive models may be currently limited.  However, improved understanding can only assist the development of better assessment and management options.