Transcript

Josh Clark (0:00)

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Chuck Bryant (1:39)

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Chuck Bryant (2:07)

should all be doing, which is composting.

Sponsor/Ad Voice (2:09)

You can learn a thing or two about it in this episode. Composting Colon, nature's most interesting process. It's really not too hard and it really means A lot. So give it a shot.

Josh Clark (2:28)

Welcome to stuff you should know from howstuffworks.com. Hey, and welcome to the podcast. I'm Josh the Man Clark. There's Charles W. Chuck Bryant. And I think I neglected to say last time. Yeah, you did. Guest producer Noel is with us.

Summary

Stuff You Should Know: "Composting: Nature's Most Interesting Process"

Air Date: March 20, 2026
Hosts: Josh Clark & Chuck Bryant
Producer: Noel
Podcast Network: iHeartPodcasts

Episode Overview

In this episode, Josh and Chuck dig deep—literally and figuratively—into the science, practicalities, and environmental impact of composting. With their signature humor and chemistry, the duo breaks down why composting is more than just a “hippie hobby,” how it works on a biological and chemical level, and how listeners can get started, no matter their ambition or living situation. The conversation ranges from municipal programs to backyard piles, with clarity on both the how and the why of composting.

Key Discussion Points & Insights

1. Food Waste: Why Composting Matters

Food Waste by the Numbers
- 40% of U.S. municipal landfill waste is food (04:07).
- The main problem: landfills are designed to be anaerobic, leading to methane production, a greenhouse gas "on the order of 70% worse" than carbon dioxide (05:16).
Environmental Benefits
- Composting diverts waste, reduces methane emissions, and produces "amazing fertilizer" for soil health (05:56).

Josh: "If you compost food waste, mostly carbon dioxide is produced. Methane's not. ... You’re keeping all that methane from being produced. And as if it couldn't get any better, you are creating an amazing fertilizer that you can use to grow." (06:12)

2. The Composting Basics: What It Is and How It Works

Definition
- Accelerates natural rot into a controlled, beneficial process (12:39).
- Results in humus (not hummus!): a nutrient-rich, earthy-smelling end product (11:34).
The Bare Minimums
- Basic ingredients: organic waste, soil (starter culture for microbes), water (moist but not soggy), and oxygen (via turning/aeration).
- Avoid using human/pet waste (night soil) and maintain a balance for good decomposition (09:36).

Chuck: "If you just want to lessen the impact a little bit on your landfill ... you can have just a little, small, little composting operation going on at your house." (09:08)

3. Setting Up Your Compost Pile

Location Considerations
- Away from the house (due to occasional smells), with partial sun/shade—ideally under a deciduous tree for seasonal coverage (16:22).
- Ensure good drainage, avoid concrete or enclosed plastic (17:20).
- Check local HOAs or municipal rules first (15:27).
Types of Compost Structures
- Single Bin: New materials added on top, decomposed humus collected from the bottom (18:36).
- Three Bin System: Materials progress between bins for staged decomposition; more "active management" (19:04).
- Tumbling Barrels: Pre-fab, easy-turn systems for convenience (20:53).

Josh: "Single bin, new stuff at the top, easy peasy. Stuff that's in process in the middle, stuff that’s finished in the bottom." (18:36)

4. What to Compost—and What Not To

What’s In:
- Kitchen waste: banana peels, apple cores, orange rinds, coffee grounds, paper filters, even napkins and newspapers.
- Yard waste: leaves, small branches, grass clippings (in moderation), pruned shrub trimmings, sawdust, rinsed seaweed/kelp (if available) (26:32-30:16).
- Smaller pieces decompose faster (28:41).
What’s Out:
- Poop (night soil), diseased plants, invasive weeds (like quack grass, buttercups, morning glory), pesticide-treated plants, meat/dairy (controversial—best to avoid due to odor and pathogens), charcoal or coal ash (see next point for nuance) (30:47-32:53).
- Special Note on Charcoal/Wood Ashes:
  - A small amount of plain wood ash is okay, but too much raises alkalinity and can harm the pile (38:25-39:10).

Chuck: "You want a more or less organic compost pile right in the end." (34:42)

5. The Science of Composting: Chemistry & Biology

The Crucial Carbon-to-Nitrogen (C:N) Ratio
- Ideal: 30:1 carbon to nitrogen.
- "Greens" (high nitrogen): fresh, pliable, often kitchen scraps.
- "Browns" (high carbon): dry, woody, paper, dead leaves.
- Too much nitrogen = "stinky," ammonia smells. Too much carbon = slow decomposition (40:39-42:20).
Oxygen Management
- Aerobic microbes need 5–10% oxygen; turning or aeration pipes help keep the pile sweet (43:09).
Water Content
- Should be damp, not soaking wet (44:08).

Josh: "It’s a chemistry experiment, but it’s also a biological experiment. You have a microcosm growing there...a food web in there." (39:20, 12:15)

6. The Compost Critters: Who Does the Work

Microbes (Bacteria & Fungi):
- Start breaking down the waste; need oxygen and the right balance for respiration and decomposition (46:02).
Worms & Invertebrates:
- Earthworms and nematodes eat and aerate; critical for breaking down and mixing compost (44:42-45:25).
Food Web Structure:
- Primary consumers (worms, fungi), secondary and tertiary consumers (predators on smaller critters).

Josh: "Worms, and especially earthworms and most types of nematodes...do so much." (45:25)

7. The Stages of Composting

Mesophilic Stage:
- Moderate temp (up to ~40°C).
Thermophilic Stage:
- High temp (50–60°C, or 120–150°F). Kills pathogens and weed seeds; rapid breakdown (48:29).
Curing Stage:
- Cooling phase; actinomycetes and fungi break down tough materials, stabilize the final product.

Josh: "If you look at the lifespan of a compost pile, from brand new to finished humus, it forms a bell as far as the temperature gradient goes." (48:29)

8. When Is Composing Done?

Finished compost (“humus”) is:
- Dark brown/black, crumbly, earthy-smelling
- Reduced to 50–75% original size
- No recognizable food fragments (53:05)
Temp drops below 100°F and stays down (52:11)
Should smell "like earth, like the word earth" (53:50)

9. Using Your Compost

Topdress gardens, lawn, trees, flower beds, or sell it
Towns increasingly have curbside compost pickup—a hopeful sign for scaling impact (55:12-55:18)

Chuck: "It's basically like the easiest way to put it without getting too scientific, is it's gonna make everything better." (54:33)

Notable Quotes & Memorable Moments

On Methane vs. CO2:

"Methane is something on the order of 70% worse… 70% more potent. How about that?"
— Josh, 05:16
On Composting's Simplicity:

"It's not hard to do and it's not expensive to do."
— Chuck, 09:07
On Picking a Spot:

"Apparently the best place to put it is under a deciduous tree. In the wintertime, there's no leaves on the tree, so the sun's going to keep it warm when it's cold. But during the summer, it's going to be shaded by the tree, so it won't dry out. It's just perfect."
— Josh, 16:21
On Struggling With Broccoli:

"Man, I hate broccoli… set it on fire… and throw that junk in there."
— Josh, 29:04
On Earthy Smell:

"And actually, one of my favorites... the actinomycytes... They are the reason that soil and dirt has its smell."
— Josh, 53:10

Timestamps for Major Segments

Food Waste Problem & Methane: 04:07–06:42
How Composting Works (Science, Activity): 11:34–13:35
Setting Up a Compost Pile (Location & Structures): 14:26–20:56
What to Compost; What Not To: 25:40–34:42
Chemistry & Ratios: 39:08–42:20
Managing the Pile (Turning, Watering, Oxygen): 43:27–44:27
Compost Food Web: 45:25–47:31
Temperature Phases/Stages: 48:29–51:36
Is It Done? Signs of Completed Compost: 51:49–54:33
Benefits & Using Finished Compost: 54:33–55:18

Resources Mentioned

Further Reading:
- Howstuffworks.com
- Cornell Composting Science for deeper scientific information (55:26)

Final Takeaways

Composting is actionable, scalable, and surprisingly simple. By managing kitchen and yard waste and understanding just a little science, anyone can turn organic waste into garden gold—while helping the planet in the process. As Josh put it:

"What you've just done is taken stuff and had it broken down into its components, unlocked it for your plants to use." (54:54)

Go forth and compost!