Interview with Dr. Michael Mulvaney

In response to my video, “You Just Composted WHAT?”, I decided to look for a soil scientist to hear their thoughts on some controversial “compostable” items that are often written about: waxed cardboard, condoms, eggs contaminated with salmonella, etc.

Who stood out most to me was Dr. Michael Mulvaney.  His blog, named “The Dirt Dude”, has lots of excellent material about soil and agriculture, and I could tell he would be able to provide some great feedback for my wonderful readers.  So here we go:

TW: When did you decide you were so interested in soil and pursue a career?  Was it an early childhood fascination for you?  Tell me a bit about how you got to where you are now.  What are your goals as an agronomist, and what would you like to see change in today’s agricultural practices?

MM: I used to help my mother garden when I was a child, but never realized that I could make a career out of it until I was a Peace Corps Volunteer in rural Bolivia.  It was then that I realized that the majority of the world’s population lives and dies by subsistence agriculture.  Unfortunately, colonial histories have made them forget how to farm sustainably, and now face serious land degradation issues.  There are several simple things that they could be doing to sustain their resources, such as crop rotation, or plowing on the contour, but they just don’t have the education to implement them.  My goal as an agronomist is to improve the livelihood of subsistence farmers around the world.

TW: What are some of the main “critters” in a compost pile on a microbial level that do the dirty work?  Are they always present in soil, and if not how do they “find” your pile?

MM: The microorganisms (MO’s) in compost are divided into categories based on their ability to withstand heat.  A fresh compost pile will activate mesophilic MO’s, which thrive at moderate temperatures.  They remain active for a few days and “eat” (metabolize) the easy stuff: soluble compounds, sugars, starches, etc.

Then the compost really starts to heat up (due to MO biological activity), and the thermophilic MO’s take over.  This is the critical temp at which pathogens are destroyed (thermal kill).  That’s why organic producers must take the temp of their compost and make sure that the temp is >55C for several days.  Keep in mind that compost is defined as having manure in it, otherwise it’s called mulch.  You want the temp to remain between 55-65C.  Above 65C, the microbes themselves can become limited, so aerate (mix) your compost to keep it below this temp.  This phase breaks down more complicated molecules: proteins, fats, complex carbohydrates, etc.

After the thermophiles have done the heavy lifting, the mesophiles take over again.  This is the finishing of the compost, and can take several months.  You’ll see the temp slowly decline during this period.

Specific MO’s that are involved in the process include bacteria (about 85% of the total MOs present), actinomycetes (which are bacteria but grow like fungi, and give that familiar earthy smell), fungi, and to a lesser extent rotifers and protozoa.  Soil microbiologists often say, “Everything is everywhere, and nature selects.”  That is, all MOs are everywhere, and it’s the microclimate that selects for them.  That’s why I think activators are bunk, and also why I believe there’s life on Europa!

TW: I’m going to name a number of different products that are frequently asked about with regards to their compostability.  For your replies, assume the composting efforts are performed at home, but if you feel there’s a different answer if the material is sent to an industrial-sized composting facility (forced air currents, high heat, constant monitoring), please respond accordingly.

Paper and cardboard constantly come up with contention as they use a variety of ingredients such as chlorine, ammonia, chloroforms, hydrochloric acid and sulfuric acid in their creation.  Do you find any of these to be dangerous for your compost?

MM: Those compounds are in such small quantities that I certainly don’t worry about them for home composting.  Besides, the MOs will take care of them in time.  In fact, ammonia is good for MOs: they use it for building proteins within their cellular structure.  Although it’s not good if your compost smells like ammonia: that’s indicative of anaerobic activity.  If that’s the case, aerate and mix, and add more carbon (sawdust).

TW: Composting laundry lint is a handy thing to do… is there any risk from traces of detergent?

MM: No, not from detergent.  Again, it’s present in such small quantities that MOs can handle it easily.  One thing about lint, though: if it contains non-natural fibers (nylon, polyester, etc.), those won’t break down.  But again, it’ll be such a small amount that some people might not worry about it.  Of course, it’s nice to keep all plastics out of the environment, so unless you use only natural fibers, consider just throwing your lint in the garbage.

TW: I began my experiment involving latex condoms, as I’ve read several articles promoting them as compostable items.  Would spermicide cause a problem, and wouldn’t latex take quite some time to break down?

MM: I don’t know how latex will act in a compost.  Let me know your results!  I’m not concerned about nonoxynol-9.  It has a long chain of ethers, which I think can be easily munched on by MOs at high temps.  The benzene ring is probably more stable, but will degrade in time as well.  The amount present is so small, that I think the MOs can handle it pretty easily.  You’d have to be one busy dude to build up the nonoxynol-9 levels to toxic quantities!

TW:  HA! There’s been a lot of salmonella outbreaks over the years, and everyone loves to compost their egg shells.  Would you consider this to be a contamination risk?

MM: Thermal kill.  Get your temp above 55C for a couple days, and you’re good to go.  Don’t add more pathogens after that time, though.

TW: What contaminants would you rank highest to be concerned about in your compost pile?  Feel free to scare me.

MM: Things that break down VERY slowly, although they’re not contaminants by any means: citrus peels, egg shells, leather, hair.  Contaminants: plastics (like those little stickers you find on fruit these days), glass, metal, etc.  Those last two are terrible because as you lovingly stick your hand in your newly finished compost, you can slash yourself on that bit of glass in there.  Most chemicals in minor to moderate quantities are easily metabolized by MOs.  Even oil is metabolized by MOs!  It’s a great way to negate the negative impact that those chemicals might otherwise have.  We call it “bio-remediation”, and we use it all the time.

TW: I would like to thank Mike for his excellent input, and hope that he will write for the page in the future.  One thing I forgot to ask him about was the crappy Sun Chips bag.  I have a feeling that falls into the “breaks down very slowly” category.  We’ll see!

Click here to see what Mike’s all about these days.

Compost Tea!

In just over two weeks, I have collected nearly a gallon of compost leachate from my compost tumbler.  Pretty awesome, just look at my excitement.  Some people have been asking me what compost tea is… well, don’t drink it!

Simply put, it’s the best organic and natural fertilizer you could use on your garden.  You can take care of an entire acre with only 5 gallons of the stuff, which is great.  To dilute it, I recommend 10 parts water to one part compost tea.  If it smells really bad, chances are it’s past its prime and not the best for use.  If you leave it outside in a bucket, you can hope to make aerobic, but ultimately you will need a small air pump to infuse air into the stuff and make it properly potent.

If you’d like to see an in-depth video for this, I always recommend the Dirt Doctor, Howard Garrett:

Have fun with it, and let me know how it goes…send me pictures!

How to Build a Worm Bin In Under 15 Minutes (video)

How To Build A Worm Composting Bin In Under 15 Minutes

Woohoo!  I just made a new worm bin. I’m going to go ahead and call it a “Bentley Bin”, which I named after Bentley Christie of . He’s the true master of vermicomposting, and I highly recommend checking him out to learn everything there is to know about worms.

Hit the Like button for the video and leave a comment for me!

I’ll be posting updates once I get my worms, which should be in about a week.

Juicer waste update

I checked out the tumbler today, WOW.  Just shy of 100 degrees, full of bugs and smells delicious.  I might make a follow-up video tomorrow.

Today my mom was in town, so we were talking about composting and fixing up my yard a bit.  She hauled away a bunch of the brush you can see in the background of all my videos, and was surprised that I gifted her a kitchen compost crock. It ends up that she’s helping coordinate a gardening event in the spring, and so we strategized about how to collect all the event’s compostable material and market the effort to the group.  It rules being able to talk trash with my mom.

Speaking of talking trash, I filmed a video today about what to do with scrap plastic that can’t be recycled, like shrink wrap, plastic bags, packaging.  I decided to sew it up into a pillow…yep!  Click HERE to check it out…

Enjoy the rest of your weekend, and send me pictures of your compost!

How to Turn Compost with The Compost Tumbler (video)

Turning Compost with the Compost Tumbler

I like this guy.  I’m glad he shows the tumbler with a lot of material in it, and how it isn’t super easy to spin no matter how you do it.  But it sure beats using a pitchfork to aerate the stuff.

This appears to be the old model without the extra ventilation slots and the additional cut-outs where you can add your compost thermometer.  If you were going to get this one, I would look for the newer version.

Either way, go Dave.  Nice work on the video!

my belated birthday present…

Today, I woke up in the morning and peeked out in the backyard… there was a big yellow kitty litter bucket.  I don’t have cats, so this could only mean one thing… juicer waste!  My compost tumbler was pretty dead at the moment as I don’t have much in the way of food scraps…but this should fire it right up.  I took the temperature before I put in the scraps: 70 degrees.

Let’s see what happens!

Sun Chips Bag to Lose Its Crunch (article)


Frito-Lay, the snack giant owned by PepsiCo Inc., says it is pulling most of the biodegradable packaging it uses for its Sun Chips snacks, following an outcry from consumers who complained the new bags were too noisy.

Touted by Frito-Lay as 100% compostable, the packaging, made from biodegradable plant material, began hitting store shelves in January. Sales of the multigrain snack have since tumbled.

PepsiCo has been working on trying to find a quieter version of the packaging since it first introduced the new bags.

Frito-Lay is returning to its old, nondegradable packaging, for five of the six Sun Chips flavors. It will continue to use the noisy packaging for its Sun Chips Original brand. It has been working on trying to find a quieter version of the packaging since it first introduced the new bags. A process that is continuing.

“We chose to respond to the consumer feedback but still want to show that we are committed” to compostable packaging, says Chris Kuechenmeister, a spokesman for Frito-Lay.

Consumers have posted videos on the Web poking fun at the new bags and lodged fierce complaints on social-networking sites. Since January, year-on-year sales of Sun Chips have decreased each month, according to SymphonyIRI, a Chicago market-research firm that tracks sales at retailers. SymphonyIRI data exclude Wal-Mart Stores Inc. PepsiCo doesn’t break out sales figures for Sun Chips.

The uproar about the new packaging was the subject of a Page One story in The Wall Street Journal in August.

This isn’t the first time PepsiCo has had an issue with its packaging. Last year, the company dumped new packaging for its Tropicana orange juice after consumers complained they didn’t like the new look.

Frito-Lay declined to disclose how much it spent to create the biodegradable packaging but it has been working on finding and testing degradable material for several years.

Just after I spend all that time to find one of these bags and put it to the test in my compost tumbler, they go ahead and pull it off the shelf.  Are people really upset with the bag being louder?  Let’s be honest, their drop in sales is because their chips taste like crap.  Who actually eats Sun Chips?

It’s really unfortunate that a company loses millions of dollars by trying to be innovative with their packaging.  They should try doing an advertisement where everyone in the commercial can’t hear each other because the bag is too loud, or have kids in a classroom make noise with the bag whenever the teacher tries to talk.

Well, let’s hope for a quieter future with compostable plastics for a louder composting revolution.

Oprah Loves Composting…

I realize I’m super late, I only just found this article.  Now I’m not an Oprah follower, but I understand why most people like her.  I’ve only seen parts of her show just a few times, and she’s very likable.  However, Oprah doesn’t seem likeable to composting.  Come on, Oprah…can you just fake it a little better so millions more people will really do it?  Man, I wish I had the influence that Oprah did.

I also highly recommend checking out the link to Daryl Hannah’s $900 worm bin.  She’s right, it is super sexy.

Looking for loads of green material to compost? Here’s a tip…

In the last week, my compost pile has been near dead as a doornail as I haven’t had much food scraps.  I’ve been lazy lately, eating a lot of takeout and going to restaurants instead of making my own food.  I think it’s the pre-winter blues already kicking in as I put my coat on today for the first time of the year (other than January 1st, nerd).

I was thinking about it a bit, as I went out partying all last night till the sun came up.  There happened to be a little snack bar at the venue, because we know that partying, dancing and eating health food go hand in hand.  They had two huge juicers, just churning out the waste that I so needed.  I asked the two ladies if they could contribute their food scraps from tonight to my compost… “Of course!” was the response.

So there you have it.  If you’re looking for food scraps to get your pile hot and bothered for the colder months, go to a juice bar and hit them up for their remnants.  You might even get a free juice out of it for putting their waste to good use, who knows?

The Genius of Jean Pain (article)

This guy is the master of thermal composting. You may have heard of him already; but if not, then get in the know.  Extremely inspiring work.  The difference here is that most people don’t have tons (literally) of material to work with for thermal compost.  From utilizing tons of underbrush that he shreds to a specific size of 1″ x 1/16″ slivers, he is able to heat his own water and collect methane to power his house and car.

I highly doubt this guy leaves his work unattended, but I can’t help but think of what the local authorities think about him and his fire risk to the local woodlands!

Learn how to make composting a breeze! Free course and new e-book are now available.