BayCEER Workshop 2026

Application of the Multi-Step-Flux Approach to Investigate Transport of Microorganisms from Soil

P 17 in Posters

The distribution of water and air, alongside many other factors in soil contributes to a spatially heterogeneous environment for microorganisms, shaping their distribution, activity and community composition. Potential transport pathways and the relative contribution of different pore size ranges to water flow and therefore transport of microorganisms is affected by changes in water content or matric potential. While the Multi-Step-Flux (MSF) approach is an established method for extending the water retention curve into the near-saturation range by applying an equilibrium flux at a fixed matric potential and progressively draining larger and then smaller pores, it has not yet been applied to investigate transport of microbes. This study investigated whether the MSF system is suitable to collect transported soil microorganisms and whether the quantities and composition change with the applied flux. Soil water effluent from two different land uses was collected by applying different fluxes using the MSF system and analyzed by fluorescence microscopy, DNA quantification and PCR to evaluate microbial abundance and composition. The MSF system was successfully used to collect samples from a distinct pore size range containing soil microorganisms. Fluorescence microscopy and DNA quantification showed different patterns for microbial abundance depending on the flux. No clear overall pattern is visible, however patterns on sample level are visible. PCR analysis of soil and effluent are ongoing and will provide further information on community composition.

Keywords: Multi-Step-Flux, MSF, microbial transport, soil microorganisms, soil pore size