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24.09.2026 14:23
Agri-photovoltaics combines electricity generation and agriculture on the same land – to ensure this works well in the long term, it is worth taking a closer look at the soil. Researchers at the Leibniz Centre for Agricultural Landscape Research (ZALF) have, for the first time, measured how the construction phase of agri-photovoltaic installations affects soil structure. Their study, published in the journal ‘Scientific Reports’, shows that heavy construction machinery can compact the soil in places to such an extent that plant roots subsequently struggle to grow. The good news is that such compaction can be largely avoided through targeted soil protection measures during construction.
The researchers investigated a newly built agri-photovoltaic plant on the ZALF research site in Müncheberg, Brandenburg. This plant combines agriculture with solar power generation on the same plot of land. Once construction work was completed in autumn 2024, they took soil samples and assessed, directly in the field, the extent to which the predominantly sandy soil had been compacted.
The result: in the areas where construction had taken place, the soil density in the subsoil ranged from 1.67 to 1.69 grams per cubic centimetre. Individual measurement points even reached values of 1.86 to 1.99 grams per cubic centimetre. By way of comparison: on an uncompacted control plot, the values were only 1.14 to 1.34 grams per cubic centimetre. The resistance offered by the soil to root penetration was also significantly higher – with soil pressure of 3.7 to 4.1 megapascals at medium depths.
Kathrin Grahmann, lead author of the study from ZALF, explains: “These values are well above the thresholds known for these soil types, beyond which plant root growth is restricted. In the case of sandy soils, such as those examined in our study, this is particularly problematic because they find it difficult to recover on their own.”
Why sandy soils are particularly at risk
Sandy soils have a weak soil structure, low carbon content and are barely able to regenerate on their own once compacted. Unlike clayey soils, they lack the ability to swell through natural processes such as freezing and thawing, or to become looser again through the action of soil organisms.
Heavy machinery was used during the construction phase. The construction work took place in damp soil conditions in the autumn, which further contributed to compaction. Within the three weeks prior to the start of construction, 32 millimetres of rain fell, with a further 83 millimetres during the construction phase.
The study shows that compaction did not only occur directly around the solar panel supports, but extended across the entire agricultural area between the rows of panels. This is due to frequent passage of construction machinery during installation.
Consequences for agriculture and recommendations for action
Soil compaction can have several negative consequences: roots grow less effectively, water seeps in more slowly and crop yields may ultimately decline. Studies show that, at similar levels of compaction, winter rye yields can fall by 22 to 43 per cent.
The researchers recommend that soil science supervision during construction should become standard practice in future agri-photovoltaic projects. This means that qualified specialists monitor the construction work and ensure that protective measures are implemented. These include, for example, restricting vehicle traffic to designated tracks, using ground protection plates and avoiding construction work when the ground is damp.
In the current study, such measures were not implemented. The reasons for this were the high cost of soil protection mats, delays in installation and tight deadlines imposed by the funding bodies. Following installation, mechanical and biological measures to aerate the soil were carried out on the study site, including the cultivation of alfalfa over a period of two to three years.
What does this mean for the future?
Agri-photovoltaic systems are being built with increasing frequency in Europe, as they are intended to help drive the energy transition whilst continuing to use agricultural land for food production. However, the study shows that, without suitable protective measures, soil fertility may suffer in the long term.
Future research should investigate whether the results are also transferable to other soil types and system configurations. Furthermore, long-term monitoring of soil recovery following installation is important. The costs of soil-conserving construction measures are difficult to quantify in general terms, but are estimated to be in the region of several thousand euros per hectare for soil protection slabs and specialised machinery. These costs would have to be borne by the project operators.
Avoiding agri-photovoltaics and using separate land for agriculture and energy production would prevent soil compaction, but would result in greater land use. Lighter construction machinery or the use of agricultural robots following installation could also help to protect the soil.
Project partners:
Leibniz Centre for Agricultural Landscape Research (ZALF) e. V., Müncheberg
State University of South-West Bahia – UESB, Brazil
Eberswalde University for Sustainable Development (HNEE)
Leibniz University Hannover
Swedish University of Agricultural Sciences (SLU), Sweden
Funding acknowledgement:
Funding for this open-access project was facilitated and organised by Project DEAL. The authors Kathrin Grahmann and Lina Rohlmann would like to thank the Federal Ministry of Research, Technology and Space (BMFTR) for its support of the SoilRob early-career research group (project ID 031B1391). This work was partly funded by the German Research Foundation (DFG) as part of the Federal and State Excellence Strategy, project EXC2070–390732324 – PhenoRob.
Dr. Kathrin Grahmann
Research Area 2 „Land Use and Governance“
kathrin.grahmann@zalf.de
Grahmann, K., Bastos, T.R.S., Donat, M., Rohlmann, L. & Reckling, M. (2026). Construction-induced soil compaction in agri-photovoltaic systems: evidence from an Arenosol. Scientific Reports, 16, 25529. DOI: https://doi.org/10.1038/s41598-026-65268-z, published Open Access under the CC BY 4.0 licence https://creativecommons.org/licenses/by/4.0/.
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