Measuring Carbon Storage on Soil Mineral Surfaces by Microbes Under Increased Nitrogen Deposition

Rachel Winslett*, Chansotheary Dang, Juan Pineiro Nevado and Ember Morrissey, Davis College of Agriculture, Natural Resources and Design, Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV 26505

Field (Broad Category): Microbial Soil Ecology (Agricultural & Environmental Sciences) 

Student’s Major: Applied and Environmental Microbiology 

The largest portion of global carbon is stored in soil as organic matter, making terrestrial ecosystems important carbon sinks. Climate change drivers such as increasing carbon dioxide and nitrogen deposition are predicted to impact soil carbon storage. Carbon that has been metabolized by microorganisms is more likely to be stabilized on clay particles and in microaggregates, which makes it less accessible for other microorganisms. Nitrogen deposition is predicted to alter the metabolism of soil microbes, however the extent of these changes in AM and ECM soil communities is poorly understood. Soil microbial communities from arbuscular (AM) and ectomycorrhizal (ECM) plants fundamentally differ in their C and N metabolism, and thus might differ in their response to N deposition. We hypothesized that AM communities will store more carbon on clay particles under nitrogen deposition than ECM communities. For the experiment, a oneweek soil incubation was conducted with carbon-13 synthetic root exudates with soils from AM and ECM plots treated with increased nitrogen deposition conditions. Afterward, soils were sieved with 2 mm, 53 μm, and 20 μm sieves to separate coarse and clay fractions. The ratio of carbon-12 to carbon-13 on the different fractions indicate where the microbes deposit the newly assimilated carbon, thus determining how the two microbial communities respond to increased nitrogen deposition and how carbon storage in soil will be impacted by future climate change drivers. 

Funding: Department of Energy 

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course