Surface soil microbial communities from New Mexico, USA

Microbial plant litter decomposition plays a major role in soil dissolved organic carbon (DOC) production, yet it is unclear how increased availability of reactive nitrogen species from anthropogenic sources will interact with diverse microbial communities to affect degradation rates. Here, we investigated the effect of inorganic and organic nitrogen supplementation on microbial CO2 production, microbial biomass, microbial community composition, and dissolved carbon and nitrogen concentrations. Microcosms of ten different soil microbial communities were incubated in the dark for 48 days at 25 C with high concentrations of ammonium nitrate and urea and blue grama grass litter; the headspace was purged periodically with ambient air. Soil communities were collected from the top 3 cm of the soil surface after removal of surface litter and stored at 6 C to avoid microbial lysis from freeze-thaw effects.