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
Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe
26.05.2017 | Oregon State University
Devils Hole: Ancient Traces of Climate History
24.05.2017 | Universität Innsbruck
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy