Submitted to: World Congress of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: 8/19/1998
Publication Date: N/A
Technical Abstract: Microorganisms have many diverse roles in soil. This investigation was initiated to compare differences in aerobic heterotrophic bacteria occurring in soil cores (250 cm depth )from two landscape positions in a field (3-5% slope) with a history of row crop production. The hypothesis tested was that measurable differences occur in the metabolic characterization of these bacteria based on source of isolation, relative to landscape position and soil depth. Bacteria were screened for metabolism of various carbon sources and for enzymatic reaction. In secondary studies, selected isolates were "regrouped" into consortia, based on the original source of isolation (landscape position and soil depth). Consortia were grown in broth culture with various carbon sources and pesticides. Results suggest bacteria isolates from cores representing the summit and bottom (depositional) landscape positions differ metabolically. Selected isolates were identified and metabolic patterns determined with Biolog substrate characterization microplates. Results were compared with cluster analysis, revealing diversity in surface vs. subsoil. Microbial comparisons were matched to both physical and chemical soil properties and to past and current management of the field. Differences in cropping history, current management, and landscape position influenced differences in the soil bacterial population, and in turn, the processes they mediate.