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@INPROCEEDINGS{Brogi:1021000,
      author       = {Brogi, Cosimo and Bogena, Heye Reemt and Köhli, Markus and
                      Hendricks-Franssen, Harrie-Jan and Dombrowski, Olga and
                      Pisinaras, Vassilios and Chatzi, Anna and Babakos,
                      Kostantinos and Jakobi, Jannis and Ney, Patrizia and
                      Panagopoulos, Andreas},
      title        = {{C}hallenges and solutions for cosmic-ray neutron sensing
                      in heterogeneous soil moisture situations related to
                      irrigation practices},
      reportid     = {FZJ-2024-00460},
      year         = {2022},
      abstract     = {Water availability is a key challenge in agriculture,
                      especially given the expected increase of droughts related
                      to climate change. Soil moisture (SM) sensors can be used to
                      collect information on water availability in a reliable and
                      accurate way. However, due to their very small measuring
                      volume, the installation of multiple sensors is required. In
                      addition, in-situ sensors may need to be removed during
                      field management and connecting cables are often damaged by
                      rodents and other wilderness animals. Hence, the demand for
                      SM sensors that do not have such limitations will increase
                      in the upcoming years. A promising non-invasive technique to
                      monitor SM is cosmic-ray neutron sensing (CRNS), which is
                      based on the negative correlation between fast neutrons
                      originating from cosmic radiation and SM content. With its
                      large measuring footprint of ~130-210m, CRNS can efficiently
                      cover the field-scale. However, heterogeneous agricultural
                      management (e.g., irrigation) can lead to abrupt SM
                      differences, which pose a challenge for the analysis of CRNS
                      data. Here, we investigate the effects of small-scale soil
                      moisture patterns on the CRNS signal by using both modelling
                      approaches and field studies. The neutron transport model
                      URANOS was used to simulate the neutron signal of a CRNS
                      station located in irrigated plots of different sizes (from
                      1 to 8 ha) with different soil moisture (from 5 and 50
                      $Vol.\%)$ inside and outside such a plot. A total of 400
                      different scenarios were simulated and the response
                      functions of multiple detector types were further
                      considered. In addition, two CRNS with Gadolinium shielding
                      were installed in two irrigated apple orchards of ~1.2 ha
                      located in the Pinios Hydrologic Observatory (Greece) in the
                      context of the H2020 ATLAS project. Reference soil moisture
                      was determined using 25 SoilNet stations, each with 6 SM
                      sensors installed in pairs at 5, 20 and 50 cm depth and
                      water potential sensors at 20 cm depth. The orchards were
                      also equipped with two Atmos41 climate stations and eight
                      water meters for irrigation monitoring. The CRNS were
                      calibrated using either soil samples or the SM measured by
                      the SoilNet network. In the URANOS simulations, the
                      percentage of neutrons detected by the CRNS that are
                      representative of an irrigated plot varied between 45 and
                      $90\%$ and was strongly influenced by both the dimension and
                      SM of the irrigated plot. As expected, the CRNS footprint
                      decreased considerably with increasing SM but did not appear
                      to be influenced by the plot dimension. SM variation within
                      the irrigated plot strongly affected the neutron energy at
                      detection, which was not the case for SM variations outside
                      the plot. The instrumented fields corroborated the URANOS
                      findings and the performance of the local CRNS was dependent
                      on a) the timing and intensity of irrigation and
                      precipitation, b) the CRNS calibration strategy, and c) the
                      management of the surrounding fields. These results provide
                      novel and meaningful information on the impact of horizontal
                      SM patterns on CRNS measurements, which will help to make
                      CRNS more useful in irrigated agriculture.},
      month         = {May},
      date          = {2022-05-23},
      organization  = {European Geoscience Union General
                       Assembly, Vienna (Austria), 23 May 2022
                       - 27 May 2022},
      subtyp        = {Other},
      cin          = {IBG-3},
      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
                      (357874777)},
      pid          = {G:(DE-HGF)POF4-2173 / G:(GEPRIS)357874777},
      typ          = {PUB:(DE-HGF)6},
      doi          = {10.5194/egusphere-egu22-6238},
      url          = {https://juser.fz-juelich.de/record/1021000},
}