This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: 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 at 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 fall 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, subsoil density ranged from 1.67 to 1.69 grams per cubic centimeter.
Individual measurement points reached values of 1.86 to 1.99 grams per cubic centimeter. By comparison, values on an uncompacted control plot were only 1.14 to 1.34 grams per cubic centimeter. The soil's resistance to root penetration was also significantly higher, reaching 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." Sandy soils have a weak soil structure and low carbon content, and they can barely 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 construction. The work took place in damp soil conditions in the fall, which further contributed to compaction. In the three weeks before construction began, 32 millimeters (1.3 inches) of rain fell, with a further 83 millimeters (3.3 inches) during construction.
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