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Nitrate in agricultural soils: Bayreuth research project seeks to enable area-wide measurement on site

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University of Bayreuth, Press release No. 066/2021, 28 May 2021

The use of large quantities of fertilisers is leading to increasing nitrate contamination of arable land worldwide. At the same time, however, there is no method currently available with which soil nitrate content can be measured continuously over a larger area. A new research project at the University of Bayreuth headed by Prof. Dr.-Ing. Gerhard Fischerauer is determined to change that. Based on electrical impedance spectroscopy, a technique is to be developed that enables large-scale nitrate measurement in agricultural fields. The Volkswagen Foundation is funding the project for up to two years from its "Experiment!" programme.


"Up to now, the nitrate content of arable soils has mostly been determined by analysing isolated soil samples in the laboratory. If, on the other hand, measurements are made in the field, using an apparatus attached to agricultural implements or vehicles, they would ideally cover a large agricultural area and provide a complete picture of nitrate pollution. This would have enormous ecological and economic advantages," says Fischerauer, Chair of Measurement & Control Systems at the University of Bayreuth.

"The relevance of our project is shown by the fact that it is one of the few projects selected by the Volkswagen Foundation for its "Experiment!" programme. The prospect of being able to launch a ground-breaking technical development for environmental protection and agriculture is also a special incentive for me personally," says project team member Luca Bifano, M. Sc.

Fischerauer points to the extensive information on soil quality that emerges from this targeted procedure, enabling more efficient cultivation of the fields. For example, farmers could reduce production costs through the targeted use of fertilisers. In addition, the costs incurred in groundwater purification necessitated by constant over-fertilisation would be considerably reduced.


In laboratory analyses of materials, electrical impedance spectroscopy (EIS) has definitely proven its worth. The measured spectra can be used to draw conclusions about the chemical composition of materials, for example foundry sand, sand mixtures (quartz, chromite), or organic material (carbon). The percentages of the respective components can also be reliably determined. But it is unclear whether this information can be obtained with the same reliability in the field.

Fischerauer and his team therefore wish to further develop electrical impedance spectroscopy so that it can be used on arable land to measure nitrate concentrations. A key challenge is that there are a number of factors that could influence or even falsify the measurements. These influencing variables include, for example, soil temperature and moisture, as well as the totality of chemical compounds contained in the soil in addition to nitrate. The desired measuring system must be able to factor in all these influences in processing measurement data.


"If our research results are promising, we intend to start a pilot project: We will build a demonstrator system and install it on agricultural equipment, such as tractors. In principle, this apparatus will make it possible to measure nitrate concentrations in the soil cheaply, quickly, and over a wide area. In individual cases, terrain-related difficulties will probably arise that may prevent the smooth use of the new system. But I am sure that agricultural science will provide the technical solutions to any such problems," says Fischerauer.

Research funding:

With its "Experiment!" funding initiative, the Volkswagen Foundation supports the start-up phase of projects in which new and unusual research ideas are to be tested. If successful, the projects provide a valuable basis for innovations in important areas of the economy and society.


Prof. Dr.-Ing. Gerhard Fischerauer
Measurement & Control Systems
University of Bayreuth
Phone: +49 (0)921 / 55-7230
E-mail: mrt@uni-bayreuth.de

Editorial office:

Christian Wißler
​Science Communication
University of Bayreuth
Phone: +49 (0)921 / 55-5356


Ralph Reindler

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