Denitrification in prairie potholes

Denitrification is a crucial aspect of the N cycle, transforming terrestrial N into atmospheric N.  While this can reduce eutrophication of aquatic systems, it can also product N2O, a potent greenhouse gas.  At present there is a critical need to understand the underlying microbiology that drives denitrification so land managers can maximize the benefits of denitrification and minimize greenhouse gas emissions. Our research consists of both field measurements and laboratory manipulations aimed at linking microbiology to ecosystem denitrification rates. We aim to identify the microbial mechanisms controlling denitrification by examining native prairie potholes and adjacent agricultural plots. 
Prairie potholes are depressions connected by shallow drainage ways.  In Iowa, prairie potholes were created apporximately 12,000 years ago whten the Des Moines Lobe of the Wisconsinan Glacial Event retreated.  Today few prairie potholes remain, as most of the landscape has been transformed into agricultural land.  Prairie potholes provide an important native landscape to study biogeochemical processes.  In this research we compare the denitrification potential in various pothole landscape positions at Kalsow prairie and from adjacent agricultural fields.  Compared to the prairie sites, cropped soils have lower total N and C contents, lower water contents and increased pools of inorganic N.  In addition this landscape provides a natural pH gradient to investigate the influence of environmental factors on the microbial mechanisms driving denitrification.