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@ARTICLE{Jakobi:909640,
      author       = {Jakobi, J. and Huisman, J. A. and Fuchs, H. and Vereecken,
                      H. and Bogena, H. R.},
      title        = {{P}otential of {T}hermal {N}eutrons to {C}orrect
                      {C}osmic‐{R}ay {N}eutron {S}oil {M}oisture {C}ontent
                      {M}easurements for {D}ynamic {B}iomass {E}ffects},
      journal      = {Water resources research},
      volume       = {58},
      number       = {8},
      issn         = {0043-1397},
      address      = {[New York]},
      publisher    = {Wiley},
      reportid     = {FZJ-2022-03311},
      pages        = {e2022WR031972},
      year         = {2022},
      abstract     = {Cosmic-ray neutron sensors (CRNS) enable noninvasive
                      determination of field-scale soil moisture content by
                      exploiting the dependence of the intensity of aboveground
                      epithermal neutrons on the hydrogen contained in soil
                      moisture. However, there are other hydrogen pools besides
                      soil moisture (e.g., biomass). Therefore, these hydrogen
                      pools should be considered for accurate soil moisture
                      content measurements, especially when they are changing
                      dynamically (e.g., arable crops, deforestation, and
                      reforestation). In this study, we test four approaches for
                      the correction of biomass effects on soil moisture content
                      measurements with CRNS using experiments with three crops
                      (sugar beet, winter wheat, and maize) based on high-quality
                      reference soil moisture: (a) site-specific functions based
                      on in-situ measured biomass, (b) a generic approach, (c) the
                      thermal-to-epithermal neutron ratio (Nr), and (d) the
                      thermal neutron intensity. Bare soil calibration of the CRNS
                      resulted in high root mean square errors (RMSEs) of 0.097,
                      0.041, and 0.019 m³/m³ between estimated and reference
                      soil moisture content for sugar beet, winter wheat, and
                      maize, respectively. Considering in-situ measured biomass
                      for correction reduced the RMSE to 0.015, 0.018, and 0.009
                      m³/m³. The consideration of thermal neutron intensity for
                      correction was similarly accurate. We also explored the use
                      of CRNS for biomass estimation and found that Nr only
                      provided accurate biomass estimates for sugar beet. In
                      contrast, we found significant site-specific relationships
                      between biomass and thermal neutron intensity for all three
                      crops, suggesting that thermal neutron intensity can be used
                      both to improve CRNS-based soil moisture content
                      measurements and to quantify crop biomass.},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {2173 - Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217) / DFG project 357874777 - FOR 2694: Large-Scale
                      and High-Resolution Mapping of Soil Moisture on Field and
                      Catchment Scales - Boosted by Cosmic-Ray Neutrons},
      pid          = {G:(DE-HGF)POF4-2173 / G:(GEPRIS)357874777},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000855257000051},
      doi          = {10.1029/2022WR031972},
      url          = {https://juser.fz-juelich.de/record/909640},
}