I recently joined a community garden and discovered that the soil in my 4' x 12' raised bed is actually compost, not the black topsoil I thought I had. I'm aware that it was made from leaves and cow manure, and I'm trying to gauge how concerned I should be about any pesticides or herbicides present in the compost. I've heard mixed opinions: one source mentioned that if the composting was thorough, the chemicals would likely have broken down, and that vegetable plants absorb very little compared to what gets sprayed directly on them. Another perspective hints that I should be more cautious, especially since my crops—peppers, broccoli, brussels sprouts, cabbage, and cucumbers—are thriving. I know testing for these chemicals can be costly and limited in scope. I'm considering digging out the compost completely and replacing it with soil, but I'd rather not do that if it's unnecessary. Any advice would be greatly appreciated!
3 Answers
Unless you're growing for specific medicinal or scientific reasons, I wouldn't stress about pesticides too much if your plants are thriving. Sure, there might be some chemicals, but they usually don't affect growth. Try to avoid green waste compost and look for those that use fresh materials. For homemade compost, you do have some safety from chemical residues due to the natural decay and filtration through the plant/animal process, especially if it’s leaf mold. Just keep in mind that there's always a certain baseline of heavy metals in any compost or soil due to environmental factors; it’s part of how the earth works. If you're still worried about contamination, maybe just stick with the compost you have, use it this year, and look into sourcing or making your own compost in the future.
It's definitely wise to have some caution. Most pesticides break down during the composting process, but there can still be exceptions like clopyralid, which has been known to persist and cause issues. Given that your plants are doing well, I wouldn't stress too much about pesticide uptake. Just keep an eye on things and consider your options down the line if you want a safer approach.
I’m actually more concerned about PFAS and heavy metals in compost than about pesticides. I plan to test my soil for those since it's easier than tracking every possible herbicide or pesticide.
If you're really worried and don’t want to risk it, you could consider planting dynamic accumulators like sunflowers in your first season. They’ll pull any potential contaminants into themselves. After that, just toss them in the trash instead of composting, and then you can start planting your edibles in grow bags for the next season. Additionally, using worm castings and mycelium can help revitalize the soil as you go.
Thanks for the insight! I also have my own compost pile at home where I put only organic materials. I'm planning on getting my soil tested for heavy metals as a precaution, and if everything checks out, I might be fine with the veggies from the community garden.