Role of Antimicrobials On P Sorption Isotherms.

To suppress microbial activity during P sorption experiments, antimicrobials such as toluene, chloroform, or formaldehyde are often added to the soil-solution mixture. The drawback to this approach, however, is that these are all organic compounds and therefore contribute dissolved organic carbon (DOC) to the solution which has been shown to affect P sorption behavior. In addition, there is a lack of studies demonstrating that microbial activity significantly affects P sorption behavior during the typical 24-hr equilibration time commonly used in P sorption experiments. Therefore, the objective of this study was to determine the affect commonly used antimicrobials have on P sorption behavior to soils. Four antimicrobials were tested as part of this study: toluene chloroform, formaldehyde, and sodium azide. Also, to determine whether the antimicrobials themselves affect P sorption behavior, P sorption studies were conducted on sterilized soils and the P sorption behavior compared between treatments. Results indicate that under most conditions, the application of antimicrobials is not needed because microbial activity is minimal when using air dried soils.