Denitrification serves as an important pathway for nitrite loss in soil and is associated with the production of the greenhouse gas nitrous oxide. The genomic traits associated with organisms encoding the genetic potential to complete denitrification to dinitrogen vs. producing or consuming nitrous oxide indicate the two types of bacteria show some additional functional differences. The objective of this proposal is to uncover how these play out in communities and how often the ability to gain or lose the genes responsible for denitrification occurs.