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Rostock (dpa / mv) - According to Rostock agronomists, microplastics can also become a problem in agriculture.

In laboratory tests by the Agricultural Faculty of the University of Rostock it was found that the germination capacity of the ryegrass used as a model plant was reduced by up to 100 percent due to the plastic content, said test director Nicole Wrage-Mönnig of the German Press Agency.

The root length was also negatively affected.

For the experiments in the laboratory, the seeds were combined with high concentrations of different types of microplastics such as polyvinyl chloride (PVC), polyacrylic, polyamide, polyester or polyethylene.

However, irrigation water that had previously come into contact with microplastics for a long time was also used.

This also had negative effects.

The concentrations in the laboratory should represent the worst possible scenario and cannot be compared with those in the field.

Research on microplastics in agriculture is still in its infancy, so far science has mostly dealt with its consequences in the oceans and especially in the animal world, said Wrage-Mönnig.

However, it is certain that the soil is also polluted.

"The problem is that the plastic parts in the soil do not break down and accumulate."

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The biologist Elke Brandes from the Thünen Institute for Rural Areas in Braunschweig also sees a great need for research on the subject of microplastics in agriculture.

But all previous investigations take place under conditions that do not correspond to those of agricultural soils, she criticized.

The concentrations there would be in the low per mille range.

Even with further accumulation in the soil, it is not to be expected that these small amounts of microplastics can have a direct impact on crop yields.

"In my opinion, the accumulation of microplastics in the soil cannot be related to other effects of global change such as climate change or soil loss through erosion on crop yields," emphasized Brandes.

It is hardly possible to completely prevent the introduction of microplastics, said Wrage-Mönnig.

This happens solely through the abrasion of car tires.

An important step towards reduction is that the use of sewage sludge in agriculture has been banned.

Mulch films are also a major burden, even if they are made from supposedly biodegradable plastic.

The decay takes a lot of time and microplastics are created.

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An additional problem is that the particles take on a spherical shape due to environmental influences.

That means a large surface area where other pollutants can accumulate.

As Wrage-Mönnig reported, the germination rates and the root length of the seedlings were measured in the laboratory after a defined growth time.

One finding is that the smaller the microplastic in the germinal area of ​​the grass, the stronger the negative effects on germination.

The effects of PVC, which is used in the manufacture of many products, were the strongest in all the tests.

© dpa-infocom, dpa: 210404-99-79463 / 2

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Rostock University, Agriculture

Thünen Institute Braunschweig