Submitted to: The 1890 Association of Research Directors Biennial Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 4/6/2011
Publication Date: 4/10/2011
Citation: Banks, M., Eivazi, F., Kremer, R.J., Motavalli, P.P., Nelson, K.A. 2011. Effects of selected surfactants on soil microbial activity. In: Proceedings of the 16th Biennial Research Symposium, April 10-12, 2011, Atlanta, Georgia. 2011 CDROM. Interpretive Summary:
Technical Abstract: Surfactants (surface-active agents) facilitate and accentuate the emulsifying, dispersing, spreading, and wetting properties of liquids. Surfactants are used in industry to reduce the surface tension of liquid and to solubilize compounds. For agricultural pest management, surfactants are an important component in herbicide and insecticide formulations that enhance adhesion of active ingredients to plant surfaces. Surfactants often directly contact soils, however, little is known about the behavior and fate of these chemicals in soil ecosystems. It is hypothesized that surfactants, upon entry into soil, may affect various chemical, physical and biological properties, and potentially affect microbial activity. The objective of this study was to determine the effects of surfactants on microbial populations in the soil. Our study included three surfactants, Activator, Agridex, and Thrust; and three herbicides, Gly-4, Atrazine, and Basagran. Treatments examined were surfactant only, herbicide only, surfactant + herbicide combinations, and non-treated controls. A greenhouse experiment was conducted using soil from the A horizon of a Leta silty clay loam (clayey over loamy, montmorillonitic, mesic, Fluvaquentic Hapludolls). Each pot (4000 g soil) was fertilized according to soil test recommendations. Pots were arranged in a randomized complete block design. Field corn (Zea mays L.) was used as the test crop and allowed to grow for seven weeks. Soil C/N ratio and DNA concentrations were determined after corn harvest. Soil samples were also analyzed using Polymerase Chain Reaction (PCR) and Denaturing Gradient Gel Electrophoresis (DGGE) techniques to determine changes in community structure among the different treatments. Results show that C/N increased with the addition of all treatments compared with non-treated control soil. Soil DNA concentrations varied with treatments. DGGE results showed variations in the DNA profiles extracted from soil with band numbers and intensities differing among treatments. Results suggest that surfactants reaching field soils may play a role in altering diversity of the soil microbial community.