Organic Fertilisers - Contamination with Microplastics Common - Take Care

Users like to belive thay are being positive for the environment by using waste organics that have been converted to organic fertilisers -small pellets or even as bagged compost or by the trailer load.

Recent studies however, confirm the presence of considerable amounts of microplastics in many of the organic fertilisers used around the world.  Most work has been conducted in Europe and North America, but it is highly likely the situation will be broadly similar in Australasia.

While some effort - or even a big effort- is made to eliminate plastics in the original waste stream, it is rarely totally successful, and they get broken up in processing eventually being in the final product as microplastic pieces [ defined as <5mm font="" in="" size="">

There is a lot of discussion about microplastics in both fresh and marine waters, and land contamination is also of  concern.

We really do not understand the potential problem with land, and issues when contamnated areas are used for food production.

More below from a recent article which appeared online.
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ISTOCK, MAERZKIND

The recycling of biological waste from homes and businesses to make fertilizer, either through composting or fertilization, is a source of microplastic pollution, according to a study published today (April 4) in Science Advances. The particles were present despite efforts to sort and sieve out plastic contaminants either before or after the waste was processed, the authors note.

“The recycling of organic waste through composting or fermentation and subsequent application on agricultural land is, in principle, an environmentally sound practice to return nutrients, trace elements, and humus to the soil,” the study authors write. “However, most household and municipal biowaste is contaminated by plastic material.”

See “Plastic Pollutants Pervade Water and Land”

Microplastics, which the new study defines as plastic particles smaller than 5 mm, result from the breakdown of plastics, and are pervasive both on land and in the oceans. While the extent of their environmental and health effects is not clear, studies have found they’re detrimental to the health of organisms such as earthworms and rodents, and that they make their way into human food supplies.

In the new study, researchers at the University of Bayreuth in Germany investigated fertilizer produced by a biowaste composting plant (which treats waste aerobically) and a biowaste digester (which uses an anaerobic process). There were fewer than 25 microplastic particles per kilogram in the compost from the first plant, while the freshly-digested fertilizer from the second plant had up to 146 particles per kilogram of the pollutants. By contrast, no microplastics were found in digestate from an agricultural energy crop digester, suggesting that the contamination in the products from the first two plants originated in the homes and businesses that were the source of the waste used.