Soil moisture and matric potential – an open field comparison of sensor systems

Abstract

Abstract. Soil water content and matric potential are central hydrological state variables. A large variety of automated probes and sensor systems for state monitoring exist and are frequently applied. Most applications solely rely on the calibration by the manufacturers. Until now, there has been no commonly agreed-upon calibration procedure. Moreover, several opinions about the capabilities and reliabilities of specific sensing methods or sensor systems exist and compete. A consortium of several institutions conducted a comparison study of currently available sensor systems for soil water content and matric potential under field conditions. All probes were installed at 0.2 m b.s. (metres below surface), following best-practice procedures. We present the set-up and the recorded data of 58 probes of 15 different systems measuring soil moisture and 50 further probes of 14 different systems for matric potential. We briefly discuss the limited coherence of the measurements in a cross-correlation analysis. The measuring campaign was conducted during the growing period of 2016. The monitoring data, results from pedophysical analyses of the soil and laboratory reference measurements for calibration are published in Jackisch et al. (2018, https://doi.org/10.1594/PANGAEA.892319).

Estimates of tree root water uptake from soil moisture profile dynamics

“…Given this finding, the conceptualisation of plant-soilwater relations as a capillary concept (e.g. Janott et al, 2010) might have essential limits with respect to state observability in the rhizosphere. Regarding multiple functions and specialisations of different roots in the root system (Kerk and Sussex, 2001), the controls of RWU and the resulting transpiration require more specific approaches with a higher spatiotemporal resolution.…”

Innovative method for installing soil moisture probes in a large‐scale undisturbed gravel lysimeter

“…These water content levels vary from 13 to 24% (Figure 5, top), with the variability being higher than expected from random heterogeneity. Bias in the absolute measurement is not uncommon in field studies, even in “normal” soils (Jackisch et al., 2020). Material texture, bulk density, clay, and organic matter can all affect the accuracy and precision of the measurements (Persson, 2001; Ponizovsky, Chudinova, & Pachepsky, 1999).…”

Deep desiccation of soils observed by long-term high-resolution measurements on a large inclined lysimeter

“…Achievement of longterm data sets is challenging using this method. Nondestructive measurement methods include cosmic ray neutrons (Rivera Villarreyes et al, 2011;Kędzior and Zawadzki, 2016), installation of TDR sensors (Li et al, 2019), thermal infrared sensors (Yang et al, 2015), resistivity measurements like the OhmMapper (Walker and Houser, 2002), capacitance measurements or neutron probes (Hodnett, 1986;Evett and Steiner, 1995). A comparison and a discussion of several sensor systems using different measurement principles are given in Jackisch et al (2020), highlighting also the need for thorough calibration before the use of such systems.…”