Incubation system

Experiments are preferably conducted in microcosm systems enabling adjustable water tension and full control of ingoing/outgoing compounds and boundary conditions in order to gain mass and energy balances including CO2 fluxes. For examples see, e.g. Poll et al. (2010), Richter et al. (2019) Calorimetric measurements can be performed in heat-protected systems with sensitive temperature measurements (megacalorimeters/cement calorimeters) or bomb / cement calorimeters (Maskow, 2013). This can be combined with techniques such as barometric process separation (Ingwersen et al., 1999; Ingwersen et al., 2008) or using alternatively a diffusion chamber-based approach (Bollmann et al., 2007). Incubation systems should have the following features:

  • Closed systems with defined soil-volume to headspace ratios and the option to detect changes in heat production.
  • Complete coverage of C balance (solids, liquids, gas) and options for determination of matter and energy distributions to various products (fluxes).
  • Control/adjustment of boundary conditions. Standard conditions: soil moisture at 60% of water holding capacity, temperature (20 °C), O2 saturation (>10%), bulk density 1.2 g/cm³.
  • Enable time-resolved (kinetics) and/or spatially highly resolved sampling.

Variation of boundary conditions such as temperature, moisture, redox potential and resulting reactions can be used as an experimental approach. Respective details have to be defined by individual projects.

 

References:

Bollmann A., Lewis K., Epstein S.S., 2007. Incubation of environmental samples in a diffusion chamber increases the diversity of recovered isolates. Appl. Environ. Microbiol. 73, 6386-6390.
Ingwersen J., Butterbach-Bahl K., Gasche R., Richter O., Papen H., 1999. Barometric process separations: New method for quantifying nitrification, denitrification, and nitrous oxide sources in soils. Soil Sci. Soc. Am. J. 63, 117-128.
Ingwersen J., Schwarz U., Stange C.F., Ju X., Streck T., 2008. Shortcomings in the commercialized barometric process separation measuring system. Soil Sci. Soc. Am. J. 72, 135-142.
Maskow T., 2013. Miniaturization of calorimetry: strengths and weaknesses for bioprocess monitoring and control. in: von Stockar U. (Ed.), Biothermodynamics - the Role of Thermodynamics in Biochemical Engineering. EFPL Press, Lausanne, Switzerland, pp. 423-442.
Poll C., Pagel H., Devers-Lamrani M., Martin-Laurent F., Ingwersen J., Streck T., Kandeler E., 2010. Regulation of bacterial and fungal MCPA degradation at the soil-litter interface. Soil Biol. Biochem. 42, 1879-1887.
Richter A., Kern T., Wolf S., Struck U., Ruess L., 2019. Trophic and non-trophic interactions in binary links affect carbon flow in the soil micro-food web. Soil Biol. Biochem. 135, 239-247.