Liang, C., G.R. Sanford, L. Lipps, R. Jackson, T.C. Balser
Presented at the All Scientist and GLBRC Sustainability Meeting (2009-05-05 to 2009-05-07 )
Soil microbial community structure has been linked to plant species, but less is known about the combined effects of plant species and agricultural management practices on soil microbial communities. Using phospholipids fatty acid (PLFA) biomarkers, we assessed patterns of community-level diversity, microbial abundance and relative abundance, and related them to past management and depth. The sites sampled were part of the GLBRC’s sustainability thrust at the Arlington Agricultural Research Station in southern Wisconsin. Samples were collected in August of 2008 at depths of 0 to10-cm and 10 to 25-cm from three alfalfa and two corn plots. Principal component analysis (PCA) of the PLFA signatures revealed that the composition of the soil microbial communities was significantly different with soil depth. Despite similar amounts of fungal, bacterial, actinomycetic and total PLFAs between alfalfa and corn in the 0 to 10-cm depth, the fungal and bacterial community structures remarkably differ explained by significantly higher AMF and gram-negative bacterial abundance in Alfalfa plots. This difference may be a response to the lack of tillage in alfalfa. In contrast, 3-year alfalfa and corn monoculture management did not result in significant microbial differences in the 10 to 25-cm depth. These results show the importance of considering past land-use into our experimental design. Pre-existing differences in soil microbial communities may serve as an important covariate in future cropping systems analyses.
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