Effect of Select Surfactants On Nutrient Uptake and Soil Microbial Activity.

Surfactants are adjuvants that facilitate and accentuate the emulsifying, dispersing, spreading, wetting, or other surface modifying properties of liquids. Many pesticides require the addition of a surfactant to improve pesticide performance in spray solution. Soils are one of the direct recipients of surfactants and little is known about the behavior and fate of these chemicals on soil ecosystem. Surfactants may compete with nutrients, pesticides, or heavy metals for the adsorption sites in soil. Additionally, surfactant may have an impact on soil microbial life. The objective of this study was to determine the effects of surfactants on nutrient uptake and microbial activities. The following categories of surfactants with trade names of Activator, Agridex, and Thrust were used.   These surfactants were coupled with herbicides Gly-4, Atrazine, and Basagran respectively. Treatments added were surfactant only, herbicide only and surfactant with herbicide. A greenhouse experiment was conducted using two different types of soils; silt clay and silty clay loam. Air dried soils of 4000 g was weighed to each pot (8 inch diameter). Each pot was fertilized according to soil test recommendations.  Pots were arranged in a randomized complete block design.   Field corn was used as the test crop and allowed to grow for eight weeks. Above ground portion of corn was harvested dried and grounded.  Plants were digested using microwave digestion and analyzed with ICP for different nutrient concentration.  Microbial study on soil samples was done using microbial biomass carbon (MBC), and gas chromatograph fatty acid methyl esters (GCFAME) to characterize the microbial community.  Denaturing gradient gel electrophoresis (DGGE) technique was used to determine changes in community structure with respect to different treatments.