ARS | Publication request: Ratio of Fungi:Bacteria as an indicator of change in soil quality

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 3, 2009
Publication Date: October 10, 2009
Citation: Borkowski, D.M., Lehman, R.M., Osborne, S.L. 2009. Ratio of Fungi:Bacteria as an indicator of change in soil quality. American Society for Microbiology North Central Branch Meeting, Lacrosse WI, October 9-10, 2009.

Technical Abstract: The removal of corn residue from cropland is of interest for ethanol production. To fully understand the implications of this residue removal on soil quality multi-discipline research is required, including microbiological investigation. This study measured the ratio of fungi to bacteria in soils from annual corn-soybean rotation plots established in 2000 subject to varying degrees of corn residue removal. Residue removal treatments implemented include removal of grain only, grain and stover, or silage. From each of the eighteen plots a 1.25” diameter bulk soil sample from 5 – 20 cm depth was collected in spring 2006. Soil was homogenized and DNA was extracted from five 0.5 g representative samples from each of the eighteen soils. DNA was then purified, combined, and concentrated. Quantitative PCR (qPCR) was conducted on the samples using group-specific fungal and bacterial primers. The initial data set acquired after six years of treatment showed the highest fungi:bacteria ratio, 0.157, in the grain-only treatment plots in soybean stage at the time of sample collection. The next highest ratio, 0.133, was recorded in the silage-cut plots also in soybean stage. Further annual sampling and analysis are necessary to generate sufficient data to indicate trends. Through continuation of this study we hope to learn how change in fungal:bacterial ratios may be used as an indicator of change in soil health and sustainability.