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@INPROCEEDINGS{Brogi:1021002,
      author       = {Brogi, Cosimo and Nieberding, Felix and Köhli, Markus and
                      Pisinaras, Vassilios and Dombrowski, Olga and Huisman, Johan
                      Alexander and Panagopoulos, Andreas and Hendricks-Franssen,
                      Harrie-Jan and Bogena, Heye},
      title        = {{F}ostering the understanding of sub-footprint
                      heterogeneity in {C}osmic-{R}ay {N}eutron {S}ensing –
                      challenges of irrigation monitoring},
      reportid     = {FZJ-2024-00462},
      year         = {2023},
      abstract     = {Cosmic-ray neutron sensors (CRNS) can measure soil moisture
                      (SM) at the field scale due to their large sensing volume of
                      tens of ha. Recently, lower instrument costs and improved
                      data processing make CRNS increasingly attractive for
                      agricultural applications. However, soil moisture in complex
                      environments, such as small fields that are irrigated or
                      cultivated differently or large fields with heterogeneous
                      soils, is still challenging to monitor with CRNS. In this
                      work, we show results from two studies that investigate the
                      effects of sub-footprint heterogeneity in Greece and
                      Germany.In Greece, we selected two ~1.2 ha apple orchards in
                      the Pinios Hydrologic Observatory that are irrigated with
                      micro sprinklers. In 2020, each orchard was equipped with an
                      Atmos41 all-in-one climate station, four water meters, and
                      12 wireless nodes (SoilNet) that monitored SM at 5, 20 and
                      50 cm depth. A CRNS with a 25 mm HDPE (high density
                      polyethylene) moderator and a gadolinium-based thermal
                      shielding was installed at the centre of each field. In
                      Germany, we selected a 14 ha potato field near Kogenbroich.
                      Based on an electromagnetic induction (EMI) soil mapping
                      campaign, in 2023, one CRNS with two detector tubes was
                      installed in the middle of the field and two CRNS with a
                      single tube were installed in the SW and NE areas, covering
                      different soil types and soil depths. These CRNS had a 25 mm
                      HDPE moderator. The potato field in Germany receives strip
                      irrigation, which is conducted from SW to NE. One irrigation
                      cycle lasts three to four days, resulting in a strong SM
                      heterogeneity. At each CRNS location, two soil moisture
                      profile probes were installed, measuring soil moisture and
                      soil temperature at six different depths. Additionally, an
                      Atmos41 all-in-one climate station, as well as a novel
                      evapotranspiration sensor based on the Eddy Covariance (EC)
                      method were installed at the central site. As the EC sensing
                      volume is of similar size as the CRNS footprint, the ability
                      of both methods to estimate irrigation deficits in a
                      heterogeneous landscape may be investigated.Results from the
                      Greek experiment show that CNRS could offer reliable SM
                      estimations only during non-irrigated periods (RMSE < 0.020
                      cm3 cm-3) while soil moisture content was underestimated in
                      both fields during the irrigation season (RMSE of 0.058 cm3
                      cm-3) due to the small field dimensions. We developed and
                      tested a novel correction approach based on neutron
                      transport simulations and an additional single SM sensor
                      located outside the irrigated area. We found that soil
                      moisture estimates can be greatly improved (RMSE of 0.031
                      cm3 cm-3) through this approach. In addition, we will
                      present first results from the experiment in Germany, which
                      provide important insights on sub-footprint heterogeneity
                      and ways to improve the use of CRNS in complex agricultural
                      environments.},
      month         = {Sep},
      date          = {2023-09-25},
      organization  = {2nd TERENO-OZCAR Conference 2023, Bonn
                       (Germany), 25 Sep 2023 - 28 Sep 2023},
      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)24},
      url          = {https://juser.fz-juelich.de/record/1021002},
}