Nitrous oxide (N2O) is well recognized as a potent greenhouse gas. Despite its effects on climate, the gas is typically considered harmless to biology. However, long-standing research has shown that N2O can become toxic through interactions with certain cobalamin dependent enzymes. This study seeks to understand whether chronic N2O exposure leads to a discernible change in the metabolic capacity of microbial communities at Harvard Forest . In addition, we are also interested in understanding how certain plant compounds inhibit nitrous-oxide producing microorganisms.