Lipps, L.A. and T.C. Balser
Presented at the All Scientist and GLBRC Sustainability Meeting (2009-05-05 to 2009-05-07 )
The productivity and sustainability of dedicated bioenergy crops may depend on their associated soil microbial communities, yet the effects of long-term management on soil microorganisms are poorly understood. This study investigates the effect of diverse bioenergy cropping systems on soil microbial community structure. At the Wisconsin Integrated Cropping Systems Trial (WICST), Arlington, WI, located on a Plano silt loam, surface (0-10 cm) and subsurface (10-25 cm) soils from high-input maize (cultivated >15 years), rotated maize/soy (>15 years), and cultivated prairie grasses (>5 years) were collected at the height of the growing season. Soils from a novel cultivated system, managed switchgrass (Panicum virgatum) (1 year), at the site were collected as well, to assess the effects of this novel cropping system. Microbial community structure was determined by analysis of phosopholipid fatty acid (PLFA) biomarkers. Principal component analysis of lipid signatures revealed that soil microbial communities from prairie treatments display significant differences from maize and switchgrass plots. Preliminary results suggest that shifts in gram-positive bacteria are responsible for the observed differences in community structure between cropping treatments. A secondary gradient suggests a separation of soil microbial communities by depth, heavily influenced by shifts in gram-negative bacteria.
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