The Selhausen Minirhizotron Facilities: A Unique Set-Up to Investigate Subsoil Processes within the Soil-Plant Continuum
Creators: name: Bauer, Felix
name: Lärm, Lena
name: Hermes, Normen
name: Vereecken, Harry
name: Vanderborght, Jan
name: Schnepf, Andrea
name: Klotzsche, Anja
Publisher: name: Forschungzentrum Jülich
Year: 2023

description: TERENO-OZCAR Conference 2023, Bonn, Germany, 25 Sep 2023 - 28 Sep 2023
description: Climate change raises new challenges for agriculture. A comprehensive understanding of whole plant responses to a changing environment is the key to maintain yield and improve sustainable crop production. Although there are many projects approaching this challenge, most studies focus on the acquisition and analysis of above-ground field data. The subsoil processes involved in plant root growth and resource acquisition are rarely in focus, since very complex set-ups are required to obtain these data on field scale. Therefore, detailed measurement of the plant roots and the corresponding soil conditions are required. The minirhizotron facilities in Selhausen (Germany) are located within the TERENO-Selhausen test site in the lower Rhine valley. They enable non-invasive longer-term studies of the soil–plant continuum on two different soils in the same climate by offering a unique set-up to record above- and belowground information over entire crop growing seasons under various field conditions and agronomic treatments. Detailed information about soil water content, soil water potential, soil temperature and root development are collected with a high spatial and temporal resolution. Above-ground measurements, such as biomass, transpiration fluxes and assimilation rates are performed additionally. In recent years, continuous development and improvement of measurement technology and data analysis has facilitated the process, transfer and access to these data. Currently several dynamic and permanently installed sensors are used within the facilities. 7 m-long transparent tubes are horizontally located in several depths. An in-house developed RGB-camera system enables root imaging along the tubes in multiple directions. The images are analyzed with a deep neural network-based analysis pipeline that provides relevant root system traits, such as total root length and root length density. To obtain the spatial soil water content variations per depth, crosshole ground-penetrating radar (GPR) measurements are performed between the tubes. The derived permittivity and hence soil water content values show a clear spatial variation along the tubes and different behaviors for various plant and soil types. Recently, a novel analysis tool to derive the trend‑corrected spatial permittivity deviation was introduced, allowing an investigation of the GPR variability independently of static and dynamic influences.The ongoing measurements currently cover five years of wheat and maize trials, including water stress treatments, sowing density, planting time, and crop mixtures. Data collected in this study are available through the TERENO data portal and can be used to develop, calibrate, and validate models of the soil–plant continuum across different scales, including soil process, root development and root water uptake models, as well as model compilations, such as single-plant and multi-plant models. Further, the data can be of direct use for agronomists and ecologists