ARS | Publication request: Compost and Biological Amendments in Potato Systems: Effects on Soil Microbial Communities

Submitted to: Northeast Potato Technology Forum Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2008
Publication Date: March 13, 2008
Citation: Bernard, E., Larkin, R.P., Tavantzis, S., Erich, S., Alyokhin, A., Gross, S. 2008. Compost and Biological Amendments in Potato Systems: Effects on Soil Microbial Communities. Northeast Potato Technology Forum Abstracts. CD-ROM.

Technical Abstract: The specific objective of this portion of the project is to generate information on microbial populations in amended and nonamended plots at a conventional site and an organic farm. Compost-treated or untreated plots were amended with one of three biocontrol organisms, Bacillus subtilis, Trichoderma virens, and hypovirulent Rhizoctonia solani AG-3 isolate 1A1, and compared to untreated control plots. Soil samples were collected three times over the course of the potato growing season, spring prior to planting, summer, and fall post-harvest. Collected samples were then analyzed by soil dilution plating for total microbial population counts, fatty acid methyl ester profiles, and substrate utilization profiles. Compost amendment was associated with a 15% increase in bacterial populations (colony counts) in the summer and a 25% increase in bacterial populations in the fall at the conventional site. Bacterial and fungal populations exhibited approximately 17% increases in T. virens amended plots at the conventional site in the summer and fall seasons, respectively. Microbial activity was significantly different in relation to the three biocontrol amendments at both sites in the summer and fall with the T. virens treatment commonly significantly higher than the other biocontrols and the untreated control plots. Compost and biocontrol amendments resulted in significant effects on soil microbial community characteristics at all sampling dates, with biocontrol effects most evident early in the season, and compost effects larger and more prominent later in the season.