Linking microbial community composition to management-relevant agroecosystem functions

Background/Question/Methods

High throughput molecular methods for taxonomic and functional characterization have revolutionized microbial ecology. In soils, these approaches have altered our understanding of the abundance and relevance of many groups, notably the Archaea. As the technology behind detection methods matures, research emphasis has shifted from describing microbial communities and their components to attempting to link this information to management-relevant functions.  Rapid growth in sequencing capabilities now makes it possible to describe communities in terms of the abundance and diversity of genes involved in key processes such as nitrogen cycling and the digestion of chemically stable forms of carbon. The practical motivations for much of this work are to identify modes of action for achieving management objectives and to develop measures for assessing changes in agroecosystem function. We present research linking microbial community composition to nitrous oxide fluxes from bioenergy feedstock cropping systems. We use PLFA profiles as well as metagenomic sequencing targeting the V6-8 region of the SSU and the nosZ gene to characterize divergence in microbial communities across these systems. We also relate these genetic metrics to in-field nitrous oxide flux measurements and to inorganic nitrogen pools in the context of site-specific responses to abiotic drivers of denitrification.

Results/Conclusions

Preliminary results largely focus on the biological signal strength available for identifying quantitative relationships between microbial community composition and nitrous oxide fluxes. In particular, we explore differences in PLFA and functional gene characteristics between no-till corn and a low-input/high-diversity mixture of prairie species, 3 to 5 years after establishment.