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@ARTICLE{Gao:864120,
      author       = {Gao, Z. and Haegel, F.-H. and Esser, O. and Zimmermann,
                      Egon and Vereecken, H. and Huisman, J. A.},
      title        = {{S}pectral {I}nduced {P}olarization of {B}iochar in
                      {V}ariably {S}aturated {S}oil},
      journal      = {Vadose zone journal},
      volume       = {18},
      number       = {1},
      issn         = {1539-1663},
      address      = {Alexandria, Va.},
      publisher    = {GeoScienceWorld},
      reportid     = {FZJ-2019-04017},
      pages        = {},
      year         = {2019},
      abstract     = {Biochar is considered a promising soil amendment, but an
                      effective method to detect and characterize the spatial
                      distribution and temporal dynamics of biochar in soil is
                      still missing. The aim of this study is to investigate the
                      ability of the spectral induced polarization (SIP) method
                      for the noninvasive detection of biochar in unsaturated
                      sandy media. In particular, a pure sand and two
                      sand–biochar mixtures with 1 and $2\%$ biochar made from
                      pine (Pinus spp.) wood by pyrolysis at 800°C were
                      investigated. The measured SIP spectra as a function of
                      saturation were interpreted by fitting a Cole–Cole model
                      to the low-frequency part of the SIP measurements. The
                      porous nature of the biochar particles strongly affected the
                      SIP response of the partially saturated sand–biochar
                      mixtures. Due to the high residual water content of the
                      biochar in a dry background, the relationship between bulk
                      electrical conductivity and water saturation was nonlinear
                      in a log–log representation. This nonlinear behavior could
                      adequately be explained with a dielectric mixing model that
                      considered the drainage of the biochar particles. Both the
                      measured phase and chargeability of the sand–biochar
                      mixtures showed a complex dependence on water saturation.
                      This was attributed to the decrease in polarization strength
                      of the biochar particles with desaturation and the
                      simultaneous increase in phase of the sand background.
                      Overall, the results of this study suggest that field SIP
                      measurements may be a promising tool for the
                      characterization and monitoring of biochar amendments to
                      agricultural soils.},
      cin          = {IBG-3 / ZEA-2},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118 / I:(DE-Juel1)ZEA-2-20090406},
      pnm          = {255 - Terrestrial Systems: From Observation to Prediction
                      (POF3-255)},
      pid          = {G:(DE-HGF)POF3-255},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000480303900001},
      doi          = {10.2136/vzj2018.12.0213},
      url          = {https://juser.fz-juelich.de/record/864120},
}