|KREMER, ROBERT - University Of Missouri|
Submitted to: Missouri Prairie Journal
Publication Type: Trade Journal
Publication Acceptance Date: 8/27/2015
Publication Date: 10/15/2015
Citation: Kremer, R.J., Veum, K.S. 2015. Soil microbiota of the prairie. Missouri Prairie Journal. 6(3 & 4):18-21.
Technical Abstract: The prairie ecosystem is often used as a benchmark ecosystem to provide a reference soil quality or soil health assessment. Current soil health assessments include measurements of soil chemical and physical indicators and of selected microbiological activities but no characterization of soil microbial composition. Microbiological indicators are needed for current soil health assessment because microorganisms are the largest segment of soil biological diversity and are responsible for critical ecological functions. Soils within the claypan soil region were collected from Tucker Prairie Natural Area from sites that were burned or not burned as part of the prairie management scheme; a reconstructed prairie at 20 years post-establishment; and a field planted to a corn-soybean rotation for more than 20 years. The soils were analyzed for microbial contents based on cellular composition of phospholipid fatty acids (PLFA). Total PLFA in soil extracts is a measure of the viable microbial biomass present in soil. Viable microorganisms have intact cellular membranes that contain PLFA. Individual PLFAs (“biomarkers”) are isolated to identify specific functional groups of microorganisms (bacteria, actinobacteria, fungi, protists) based on the PLFA patterns unique to each group. Our PLFA analysis showed that burned and unburned sites at Tucker Prairie did not differ greatly in total microbial biomass or in microbial community composition. The corn-soybean field had the lowest soil PLFA content suggesting that tillage and continuous row-crop production supported lower microbial community biomass as a result of reduced organic inputs and reduced soil organic matter levels. The microbial groups, mycorrhizal fungi, Gram-negative and -positive bacteria, actinobacteria, anaerobic bacteria, and protists were highest in the native prairie (both burned and unburned), intermediate for the reconstructed prairie, and lowest in the cultivated site. Each of these groups contributes to interlinking functions that are indispensable for ecosystem processes. The abundance of all microbial groups in prairie ecosystems assures biological functionality of soil. Native prairies exceeded all other management systems on claypan soils in supporting highly diverse soil microbial communities based on PLFA characterization. The reconstructed prairie shows progress in building up soil microbial communities since transitioning from row crop production over 20 years ago. The continuous presence of vegetation, lack of soil disturbance, and greater organic inputs point to the differences between soil microbial communities of the prairie sites and the cultivated row crop system. Previously reported soil health assessments combined with microbial community characterization were sensitive in contrasting effects due to land management. We now plan to document whether soil community responses shown for claypan soil sites are similar for prairie sites on soils with considerably different properties. A complete testing program will be important in assessing the soil health and biological status of prairie remnants that have diverse histories of burning, grazing, haying, and other vegetative management. Knowledge of impacts of past management of prairies will improve understanding of the current conditions of native sites and guide management developed for restoration and reconstruction of prairie systems on soils transitioning from crop production or under remediation from other management systems.