Innovative measuring device enables the water content of biological soil crusts to be measured for the first time
Biological soil crusts comprising lichens, algae and mosses play an important role in the earth’s ecosystems. They fix carbon dioxide and nitrogen while giving off significant amounts of the greenhouse gas nitrous oxide. Information on soil moisture is of vital importance to investigate their fixation and release processes and to understand them in detail.
The newly developed soil moisture sensor being used in a lichen-dominated soilcrust in the Succulent Karoo, a semi-desert in South Africa.
Bettina Weber, MPI für Chemie
The site, where the soil moisture sensors are installed as a compound of climate stations, is protected from grazing animals by means of a fence.
Bettina Weber, MPI für Chemie
Previously, no sensor existed that could measure the water content in the top millimeters of the soil with sufficient accuracy. This gap has now been closed by a new development of Bettina Weber and her colleagues at the Max Planck Institute for Chemistry in Mainz, as can be read online in the ‘Early View’ section of the “Methods in Ecology and Evolution” Wiley Online Library. They have managed to construct an appropriate soil moisture sensor, which delivers reliable data, as well as being cost-effective and flexible to use.
Up to now, the available methods were only moderately suited to at least approximately determine the water content within the top soil level. “The only sensor that can be used in the uppermost layer merely measures whether the organisms are active, but not the water content. All other soil moisture sensors measure the water content in deeper layers, making them totally unsuited for applications in biological soil crusts,” Bettina Weber, group leader in the Multiphase Chemistry department, describes the problem.
Because the soil moisture in the top five millimeters is essential for the activity, productivity and surface transfer rate of periodically wet organisms, however, Bettina Weber tried to determine this unknown factor by means of an own new development.
Together with her research team, she found a method that enabled her to determine the soil moisture by means of its conductivity. The key component of the measuring device is thus a conductivity sensor.
The calibration of the sensors posed the biggest challenge: Because the conductivity of the soil is affected not only by its moisture, but also by factors such as its granularity and salt content, the sensors must always be calibrated within the substrate that is being measured. It was only after numerous attempts that the researchers were able to develop a reliable method that enabled them to assign the conductivity values to the corresponding water content values.
“As it is really time-consuming to create calibration curves in the laboratory after the field measurements, we have also developed a method for creating a calibration curve that is slightly less accurate but requires fewer field measurements,” states Thomas Berkemeier, doctoral student in the Multiphase Chemistry department, who developed the mathematical approach for calculating the calibration curves.
As a whole, the new development of the Mainz scientists convinces due to its numerous advantages: Firstly, thanks to its simple structure and robust construction, the sensor can be deployed universally in all kinds of soils around the world. Secondly, the low acquisition costs make it possible to install multiple sensors simultaneously, allowing small-scale patterns and dependencies to be registered in a statistically reliable manner, something that wasn’t possible previously.
With simple adjustments, the newly developed soil moisture sensors can be used for measurements over larger soil areas. This makes them potentially useful not only for research projects on biological soil crusts, but also for industrial applications, for instance in the processing of concrete.
The Max Planck scientists have obtained protection for their invention and have registered the moisture sensor as a utility patent. Currently, Bettina Weber is already working on a further development of the sensor, to make it ready for utilization in distributed sensor networks.
B. Weber, Th. Berkemeier, N. Ruckteschler, J. Caesar, H. Heintz, H. Ritter, H. Brass: “Development and calibration of a novel sensor to quantify the water content of surface soils and biological soil crusts”, Methods in Ecology and Evolution (2015), doi: 10.1111/2041-210X.12459
PD Dr. Bettina Weber
Max-Planck-Institut für Chemie
55128 Mainz, Germany
Additional information about biological soil crusts:
Biological soil crusts consist of a community of cyanobacteria, lichens, algae and bryophytes, together with fungi, bacteria, and archaea, which grow in the upper three to five millimeters of the soil, forming a hardened layer. They exist in dry regions throughout the world and occupy approximately 20 million square meters, which is almost as large as the surface of South America. All the organisms in biological soil crusts are poikilohydric, which means that they are only active when the soil is sufficiently moist, but survive in an inactive state under dry conditions.
Dr. Susanne Benner | Max-Planck-Institut für Chemie
The pace at which the world’s permafrost soils are warming
16.01.2019 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
Using satellites to measure rates of ice mass loss in glaciers
16.01.2019 | Friedrich-Alexander-Universität Erlangen-Nürnberg
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.
Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
17.01.2019 | Physics and Astronomy
17.01.2019 | Materials Sciences
17.01.2019 | Information Technology