Pesticides in Worm Composting? Should We Worry?

An entrepreneurial reader writes about the worry of pesticides in worm composting:

“I am thinking of starting a system of collecting fruit + veggie scraps from people at my church to upscale my worm composting. (The past year I’ve had two 20-gallon bins– so approximately 4 sq ft– and now I’d like to try a 32 sq ft raised bed w/ roof to keep out rain…. I’m fortunate to live in mild climate _________, so I don’t have to worry much about freezing or many days above 90 degrees.)

My wife asked a good question: if the majority of the fruit + veggie scraps are not “organic,” wouldn’t there be some chemicals in the resulting worm castings? My thoughts on why this shouldn’t be a big concern:

The process of the worms/microbes digesting the scraps helps to “clean” the scraps. (I thought I heard this somewhere, but cannot confirm it.)

The slower process I am trying** allows time to break down any chemicals.

3) Since the source is very diverse (scraps from many peoples’ homes), it lessens the chance of any one chemical in large quantity in the original scraps…. Furthermore, some of the coco coir bedding is digested, further diluting any chemical. (I’m hoping to transition to mixing in old leaves as well, as bedding.)

4) The resulting worm castings (a) are still mixed in with some clean bedding material and (b) will only make up a small % of final soil used to grow food.

** I plan to harvest 20% to 25% at a time, every few months (and add new bedding)…. So a good % of the final product will be aged 1-2 years when it is harvested. (Rather than a quicker flow-through system.)

Is this a reasonable explanation for why I shouldn’t be concerned about any chemicals on the fruit/veggie scraps? (Should I consider using a 3-bucket system to rinse off scraps quickly, before giving to the worms?…. People typically rinse the outside of fruits/veggies before using them, so that may be redundant.)”

There is a certain type of purist who always insists that you do everything right every time or you’re wrong, wrong, wrong. I’ve faced this sort of thing many times over the years with my gardening experiments, as they have been done before the face of the public. Your wife’s question is a good one – it’s the sort of question I would ask, too – but pursuing perfection in something like this will drive you insane and is likely to keep you from actually getting anything done.

For example, let’s say Ann decides to plant a small patch of beans and sell the beans. To do so, she rents a tiller and turns under the grass, then makes beds. As she’s doing so, her super-organic next-door neighbor Stella is out in her yard, going through some weird centering ritual on a mat in the grass in her tight, sustainably-harvested fair-trade yoga outfit. She hears the raking and it breaks her concentration on the Transcendant Earth Mother Spirit, so she peers over the fence at Ann.

“Hey Ann… what are you doing?”

Ann looks up from her raking and freezes. Stella’s look is piercing. She’s judging her for something but she doesn’t know what… yet. But she knows she will in a moment.

“Planting beans,” Ann squeaks.

“Oh,” Stella says. “I see.”

“Yep,” Ann says, forcing a smile. “Just planting beans.”

“Did you plant them yet?” Stella says.

“Not yet. Just finishing the beds,” Ann says with a wave towards her neat rows.

“I hope you didn’t spray weed killer.”

“No,” Ann said. “I’m growing them organically.”

Stella snorts. “But you tilled.”

“Yes…” Ann says.

“So you destroyed all the soil life,” Stella continues.

“I needed the ground loose for the beans.”

Stella shakes her head. “People don’t think. You should have used deep mulch.”

“But… I don’t have mulch.”

“You should have planned ahead,” Stella snips. “You could have mulched it last year, then it would be loose now.”

“You mean, mulching… like where you lay down cardboard and cover it with wood chips?”

“Cardboard!” Stella squeaks. “Are you kidding? Will all the glues in it?”

“Well, you gotta suppress the weeds…”

“Weeds help fix the environment, Ann,” Stella says. “How dumb are you?”

Ann winces and reaches into her pocket for a packet of beans, pulls it out and rips the top off to start planting.

“Wait just a minute there,” Stella snaps. “What are you planting?”

“Beans,” Ann says, exasperated. “I told you!”

“But you said you were growing organically!” Stella says.

Ann looks at the packet, at the ground, and then at Stella. “I’m not using any poisons.”

“Are those beans organically grown?”

“I got them from the Feed n’ Seed,” Ann says, looking at the packet.

“Are they hybrid?”

“I don’t think so,” Ann says. “They’re Cherokee Wax.”

“Omigosh, Ann… do you even hear yourself? What right have you to plant those?”

“What do you…”

“…and I’ll bet they were grown with pesticides. Tons of pesticides! And seed farms are like puppy mills, forcing plants just to breed so we can have fancy gardens. It’s disgusting!”

“It couldn’t be that much pesticide, they’re so tiny…”

“Even if there’s none, they still won’t be organic! Have you ever heard of acid rain? Or all the fossil fuel particulates in the air? And your water is full of chloramine and prescription drugs! And organic fertilizers are from factory farms, and-“

The sound of sparkling New Age chimes fills the air, interrupting Stella’s rant.

“Oh drat,” she says. “That’s my phone. Hello, Karen? Yes, we’re still on… okay, I’ll meet you at the…”

Her voice trails off as she walks back towards her house, leaving Ann to her evil plot of death beans.

Ann looks at the little seeds in her hand, innocent and round. She takes a deep breath, then starts pressing them into the warm earth.

…

If it’s food scraps you’re throwing in, well – yes – they’ll have some traces of poisons. But since the original consumers of the food aren’t dropping dead right and left, you can reasonably assume the amounts are quite tiny. And after further degradation and reincarnation into finished vermicompost, those toxins will be lessened even further.

Do your best. The compost will be great. You do have a large diversity of inputs, plus composting is like magic, fixing all kinds of evils.

Press on. I won’t tell Stella.

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