title: Application of terahertz radiation to soil measurements: initial results.
abstract: Developing soil sensors with the possibility of continuous online measurement is a major challenge in soil science. Terahertz (THz) electromagnetic radiation may provide the opportunity for the measurement of organic material density, water content and other soil parameters at different soil depths. Penetration depth and information content is important for a functional soil sensor. Therefore, we present initial research on the analysis of absorption coefficients of four different soil samples by means of THz transmission measurements. An optimized soil sample holder to determine absorption coefficients was used. This setup improves data acquisition because interface reflections can be neglected. Frequencies of 340 GHz to 360 GHz and 1.627 THz to 2.523 THz provided information about an existing frequency dependency. The results demonstrate the potential of this THz approach for both soil analysis and imaging of buried objects. Therefore, the THz approach allows different soil samples to be distinguished according to their different absorption properties so that relations among soil parameters may be established in future.
authors.affiliation: Department Engineering for Crop Production, Leibniz-Institute for Agricultural Engineering, Max-Eyth-Allee 100, 14469 Potsdam, Germany. vdworak@atb-potsdam.de
authors.forename: Volker
authors.initials: V
authors.lastname: Dworak
authors.forename: Sven
authors.initials: S
authors.lastname: Augustin
authors.forename: Robin
authors.initials: R
authors.lastname: Gebbers
mesh_terms: D000042:Absorption; D018552:Daucus carota; D004784:Environmental Monitoring / Q000379:methods*; D007887:Fabaceae; D021621:Imaging, Three-Dimensional; D016014:Linear Models; D009930:Organic Chemicals / Q000032:analysis; D012015:Reference Standards; D012815:Signal Processing, Computer-Assisted; D012987:Soil / Q000737:chemistry*; D055053:Terahertz Radiation; D014867:Water / Q000737:chemistry
chemical_list: D009930:Organic Chemicals; D012987:Soil; D014867:Water