Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/24/2003
Publication Date: 11/2/2003
Citation: FICKLIN, R.L., KREMER, R.J., FANG, M. VARIABILITY OF MICROBIAL ACTIVITY AND POPULATIONS ACROSS LANDFORMS BASED ON SELECTED ENZYMATIC ASSAYS AND PCR ANALYSES. AGRONOMY ABSTRACTS. 2003. CD-ROM (UNPAGINATED). AMERICAN SOCIETY OF AGRONOMY. MADISON, WI.
Technical Abstract: Variation of soil chemical and physical properties across forest landscapes is well documented. However, variation in soil microbial populations, including variance in genetic and carbon oxidation potential, is not well understood. Previous research in the Ozark Highlands of Missouri showed a positive correlation of soil organic carbon concentrations and rock content. To better understand the mechanisms behind these findings, enzyme activity and DNA analyses were conducted on selected samples from a shoulder slope landform in the earlier Ozark study. Four soil samples were selected: 2 from both the A and Bt horizons of a Clarksville stony silty clay loam (loamy-skeletal, siliceous, mesic Typic Paleudult). Enzyme assays were conducted to measure dehydrogenase and acid phosphatase activities, and similar assays were performed for fluorescein diacetate (FDA) activity to assess potential degradation of complex organics. After polymerase chain reaction (PCR) amplification, the PCR products from soil DNA extracts were subjected to DGGE (denaturing gradient gel electrophoresis) to separate the different DNA fragments. Using cluster analyses, DNA banding profiles showed very similar bacterial communities in surface A-horizon samples (88% similarity), but soil microbial community profiles for the Bt-horizons were very dissimilar (50% similarity). These results suggest that microbial diversity may increase with depth; however, enzymatic activities indicated no statistically significant differences among landforms and horizons.