Soil Sci. Soc. Am. J. http://doi.org/kqg (2013)

Elevated atmospheric carbon dioxide concentrations along with decreased precipitation have the potential to alter soil microbial functioning with implications for the large soil carbon component of the carbon cycle. Such changes may accentuate or attenuate climate changes through feedbacks to the atmosphere.

Engil Pereira, from the Department of Plant Sciences, University of California, USA, and co-workers investigate these relationships. They used elevated CO2 and reduced precipitation treatments at a soybean free air CO2 enrichment (FACE) experiment to study the response of soil carbon fractions and soil microbial distribution across soil zones.

In line with previous research they found that elevated CO2 did not affect soil carbon, nitrogen concentrations or bacterial abundance. Reduced precipitation, however, was found to lead to an increase in the formation of microscopic soil aggregates that provided protective microhabitats for soil microorganisms — indicated by greater microbial abundance in these microaggregates in reduced precipitation plots. These results suggest a degree of microbial resilience due to a better structured soil under reduced soil moisture conditions.