Plastic in my soil from Recology Organics premium compost

Asked May 22, 2019, 12:58 PM EDT

Early spring, I purchased what I assumed was high quality compost from Recology Organics in North Plains. My plants are growing wonderfully but I have noticed small bits of plastic in my soil. I called and they noted that they obtain their materials from Portland Compost and that it is a known issue that sometimes waste products such as plastic end up in the compost they sell. Their website does not disclose this.

I am beside myself as I pick through my garden beds and try to clean out solid waste, mostly plastic. My question for you is what do you recommend? Is there any data regarding the impact of plastic in soil has on plants? Is there a credible health concern?

Also, what would you recommend for next steps: Should I dig out all the soil and try to start fresh? Would picking it out be effective? Any input would be helpful.

I included photos of the amount of garbage I found in about 10 minutes of picking through and the perimeters of where I found this (marked by gardening gloves).







Multnomah County Oregon compost

3 Responses

Thank you for your question. Although I am answering this as a Master Gardener, I am also a Master Recycler, and visited Recology during our training. I have also purchased their compost and experienced the same unwanted materials. This reflects the carelessness that those in the Metro area have about including plastic in their compost bins, and the plastics are almost impossible to filter out. It is the same basic issue as that which stopped our recycled materials going to China.

An answer to your questions is really twofold: first, what are the health effects and long term consequences? Second, what solutions are there?

I'm not sure how much you want to dive into the science of plastics, but here is an excerpt from a very recent article (https://ag.tennessee.edu/biodegradablemulch/Documents/Microplastics-soil-Factsheet-formatted.pdf)
that says: " Residual plastic fragments can adsorb pesticides used in crop production or plasticizers that are employed in the manufacture of the plastics that may be released during plastic breakdown, leading to heightened and toxic levels of the agents in nearby soil. The long-term fate of plastic fragments in soil is unknown. Recent reports predict that plastic fragments may reside in soils for over 100 years due to the near-absence of oxygen and ultraviolet radiation from the sun."

The removal question is a combination of aesthetics and your desire to get the plastic in an appropriate space other than the garden. If you want to rid your soil of the plastics due to concerns about the issues addressed above, and you have time to do so, by all means get it out! Of course, if you have space, another solution is to use your own organic materials to make your own compost, where you can control what goes in:
https://extension.oregonstate.edu/gardening/techniques/composting-publications-resources-plans

We don't have any evidence to indicate the amount of toxins which will be in the purchased compost before it reaches you, but cutting down on future contamination of the food chain may be worth your time. Good luck!

Thank you so much for this thoughtful and helpful response. I think I will do my best to pick out the garbage that I can and then replace the soil at the end of the season.

I also wanted to note that I was able to discuss my concerns further with the manager who was very responsive and open to feedback.

We have had some issues with rats when we tried composting in the past, but I think we are ready to problem solve and find a way to make it work! I'd like to follow up on the link that you provided.

Thanks again.

You’re most welcome! Perhaps you’d consider becoming a Master Recycler (http://www.masterrecycler.org/) or a Master Gardener (https://extension.oregonstate.edu/mg/metro/become-master-gardener). Happy gardening!