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@ARTICLE{Glanville:820998,
      author       = {Glanville, H. C. and Hill, P. W. and Schnepf, A. and
                      Oburger, E. and Jones, D. L.},
      title        = {{C}ombined use of empirical data and mathematical modelling
                      to better estimate the microbial turnover of isotopically
                      labelled carbon substrates in soil},
      journal      = {Soil biology $\&$ biochemistry},
      volume       = {94},
      issn         = {0038-0717},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2016-06255},
      pages        = {154 - 168},
      year         = {2016},
      abstract     = {The flow of carbon (C) through soil is inherently complex
                      due to the many thousands of different chemical
                      transformations occurring simultaneously within the soil
                      microbial community. The accurate modelling of this C flow
                      therefore represents a major challenge. In response to this,
                      isotopic tracers (e.g. 13C, 14C) are commonly used to
                      experimentally parameterise models describing the fate and
                      residence time of individual C compounds within soil. In
                      this study, we critically evaluated the combined use of
                      experimental 14C labelling and mathematical modelling to
                      estimate C turnover times in soil. We applied 14C-labelled
                      alanine and glucose to an agricultural soil and
                      simultaneously measured their loss from soil solution
                      alongside the rate of microbial C immobilization and
                      mineralization. Our results revealed that chloroform
                      fumigation-extraction (CFE) cannot be used to reliably
                      quantify the amount of isotopically labelled 13C/14C
                      immobilised by the microbial biomass. This is due to
                      uncertainty in the extraction efficiency values (kec) within
                      the CFE methodology which are both substrate and incubation
                      time dependent. Further, the traditional mineralization
                      approach (i.e. measuring 14/13CO2 evolution) provided a poor
                      estimate of substrate loss from soil solution and mainly
                      reflected rates of internal microbial C metabolism after
                      substrate uptake from the soil. Therefore, while isotope
                      addition provides a simple mechanism for labelling the
                      microbial biomass it provides limited information on the
                      behaviour of the substrate itself. We used our experimental
                      data to construct a new empirical model to describe the
                      simultaneous flow of substrate-C between key C pools in
                      soil. This model provided a superior estimate of microbial
                      substrate use and microbial respiration flux in comparison
                      to traditional first order kinetic modelling approaches. We
                      also identify a range of fundamental problems associated
                      with the modelling of isotopic-C in soil, including issues
                      with variation in C partitioning within the community, model
                      pool connectivity and variation in isotopic pool dilution,
                      which make interpretation of any C isotopic flux data
                      difficult. We conclude that while convenient, the use of
                      isotopic data (13C, 14C, 15N) has many potential pitfalls
                      necessitating a critical evaluation of both past and future
                      studies.},
      cin          = {IBG-3},
      ddc          = {570},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {255 - Terrestrial Systems: From Observation to Prediction
                      (POF3-255)},
      pid          = {G:(DE-HGF)POF3-255},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000370094100016},
      doi          = {10.1016/j.soilbio.2015.11.016},
      url          = {https://juser.fz-juelich.de/record/820998},
}