How To Manage a Compost Pile Using Temperature

compost temperature chart

I’ve always been confused about when to turn a compost pile. Some people suggest lots of turning while others don’t turn at all. I built a pile in December using a technique I learned from Will Bakx, soil scientist and operations manager of Sonoma Compost. Bakx recommends keeping the pile between 131° F (55° C) and 163°F (72°C) for a period of 15 days. The only time you turn is when the pile starts to dip below 131° F or to prevent the pile from going above 163°F.

The technique is simple–all you do is take the temperature once a day with a compost thermometer and write down the result on a calendar. The graph above is the result that I got from a pile made out of horse bedding, chicken manure from our hens, plant materials, straw and brew waste from a local brewery.

The red area on the chart is the thermophilic temperature range (135° -160° Fahrenheit). The dip you see at day 15 is the one time I turned the pile so that I could keep it in the thermophilic range. Using temperature as a clue to when to turn the pile has a number of advantages:

  • You can make sure that the pile does not get too hot. Above 160° F  you start to kill off the thermophilic bacteria that decompose your pile. To decrease temperature you turn and add more carbon material and water.
  • Washington State University recommends subjecting all of the pile to temperatures above 150° F to kill potential pathogens. I’m fairly certain that, with the turn I did at day 14, all of the pile got up to 150°F.
  • Weed seeds are killed above 130°F–another reason to watch temperature.
  • Failing to get high temperatures can be an indication of too much carbon or a lack of water. To correct, add more nitrogen and water and turn.
  • A loss of temperature could indicate that the pile is going anaerobic. The solution is to add more carbon material and turn.

Once the pile has had 15 complete days over 131° F you just let it sit. Compost is done when it is dark, smells like earth and you can’t recognize the original ingredients. It will likely be several months before it’s ready to use. I’ve found that I need to turn the pile periodically and add water after the initial thermophilic period due to our dry climate.

The mass of the pile is a factor as well–I’ve found that it needs to be a minimum of one cubic yard of material to start with. So I save and scavenge materials that I can use to build a pile all at once. The small trickle of kitchen scraps we generate each day goes into our worm bin.

Despite the geekery with using a compost thermometer, I’ve found that this method saves labor. Back breaking turning only happens when it’s necessary.

Hay Hooks–The New Hipster Accessory?

With so many city chickens I predict that hay hooks will become just as indispensable to the urban hipster as is the fixed gear bicycle. After years of hauling staw bales up the 30 steps to our house (to use as bedding for the chickens) I just broke down and bought a pair.

A vaquero at the feed store intervened with a neat tip when he saw me struggling to use my new hay hooks to load some bales into a friend’s truck. Here’s what he showed me. Note the red arrow in the photo above. Odds are with new hooks that this distance needs to be shortened a bit. My hay hooks were much easier to use after the feed store guy bent them using one of the anchor points in the truck bed.

In addition to the steps, my other reason for owning hay hooks is that I have to navigate bales down a narrow side yard. Hay hooks make the maneuver above a lot less awkward.

Now when will we see Bianchi come out with the hay hook equivalent of the Pista?

Ladies of Manure 2013 Calendar

Just when our Kickstarter fatigue has reached terminal limits, this crazy pitch shows up in our mailbox to make our day. Two words: Humanure Cheesecake.

(Err…two words you really don’t want to see together, ever,  now that I think about it. Sorry.)

As teachers, we spend a lot of our time trying to convince people to mulch and compost. Return it all to the earth, people!

We’re particularly fond of throwing down the humanure* gauntlet, partially because it really is a very important subject,  and partially for the shock factor and the giggles. Some audiences are primed for this challenge. For others, it’s the first time they’ve ever heard of the concept, and by the look on some faces, I imagine them thinking:

  • “Nope. Not even if civilization is burning down around my ears.”
  • “Note to self: Never visit these people at home.”
  • “They want me to keep poop around the house. Poop. Around my house.”
  • “Hmm, I’m sensing some sort of potty-training trauma here. Definitely an unhealthy anal obsession.”
  • “Funny, they don’t look like hippies.”

It’s an hard nut to crack, the poop nut. This environmental non-profit called The Fertile Earth Foundation is going about in a bold way, by trying to make manure sexy and fun. To be fair, the calendar isn’t all about humanure. (Then it would have to be called Jenkins Girls Gone Wild or something.) It’s about composting of all sorts, but humanure certainly gets much more play in it than it does in your average cheesecake calendar.

Take a look. They’re doing a Kickstarter to raise printing funds. What do you think? Think it will turn people on to the wonders of decomposition? What do you think it will take to make even basic composting a more commonplace activity? Do you humanure? If not, what keeps you from doing so?

*If humanure is new to you, check out the Humanure Headquarters for everything you could possibly want to know.

Aerated Compost Tea: Does it Work?

There’s a lot aerated compost tea brewers on the interwebs!

I’ve been asked by Urban Farm Magazine to write a short piece on the pros and cons of aerated compost tea (ACT for short). I’ve been sifting through the peer reviewed literature on the subject. Most of the studies show, at best, mixed results. And, honestly, my bias is against gardening techniques that require gadgets or novel techniques with no analog in nature. I’ve also tried it myself and found that a thick mulch of plain compost seems to work better.

That being said, I want to present a balanced story. I’m interested in hearing from readers about their ACT experiences. Have you tried it? Do you think it works? Or are you skeptical? Leave a comment or send me an email with your name, where you live and whether ACT did or did not work for you. I’d like to gather some anecdotal reports for the story and your help is greatly appreciated.

For those of you not familiar with ACT, here’s a good explanation with some resources via Permaculture Magazine: What is compost tea (and how do you make it)?

On the con side of ACT, horticulturalist Linda Chalker-Scott has a set of pdfs as well as a long list of ACT studies on her gardening myths page.

The Fine Art of Worm Grunting


For your Monday viewing pleasure we have two videos showing worm grunting in Florida.

Worm grunting is a technique used to lure worms out of the soil to collect as fishing bait. Basically, you take a stick (called a “stob”), pound it into the ground and rub a metal rod (known as a “rooping iron”) against the top of the stob. The deep vibrations are said to mimic the sound of burrowing moles, the natural predator of worms. When they sense the vibrations, the panicked worms crawl to the surface of the soil. (The high population of earthworms in the area profiled, upwards of 1 million per acre, makes grunting a sustainable practice.)

In England, grunting is called “worm charming”. And yes, there are competitions–in Sopchoppy, Florida, Shelburne, Ontario, and South Devon, England.

Kelly adds: Attn: geeks! After viewing, shall we discuss whether Dune author Frank Herbert knew about grunting…er…thumping? Were the Shai-Hulud fleeing even more terrifying SandVoles?

What Are Your Favorite Compost Materials?

Root Simple’s new composting game for your Xbox!

I wish I could source compost pile materials from our yard. But lead and zinc contamination in our soil make that a dodgy proposition without doing a lot of expensive lab tests. And I never seem to have enough materials even for our modest vegetable garden. So in the past I’ve used:

  • horse bedding
  • chicken manure from our own chickens
  • alfalfa hay (kinda spendy these days)
  • straw (takes a long time to break down)
  • spent grain from a local brewery
  • vegetable scraps from the farmer’s market

Once again I’ve got to build another pile and I’m interested in hearing from readers about compostibles you’ve used. Do you have a good source for stuff to compost? What are some of the things you’ve managed to scavenge? Comments!

Tips on Composting from Will Bakx of Sonoma Compost

Sonoma Compost’s composting operation.

On Thursday at the National Heirloom Exposition, Will Bakx, soil scientist and operations manager of Sonoma Compost, gave a rapid fire lecture on the nitty gritty details of composting. Here’s some of his useful tips:

Temperature and Turning
Compost should stay above 131ºF for 15 days to kill pathogens. Bakx recommended getting a thermometer to check the temperature every day during the initial period and using Sonoma Compost’s handy Temperature/Turning Sheet (pdf) to keep track of the temperature of the pile. If the pile dips below 135ºF, turn it. If it doesn’t get up to temperature, add more nitrogen containing materials. If it gets above 163ºF, add more carbon containing materials. After the initial turnings just let it sit unless you have to turn to add moisture.

Bakx believes that you should turn as little as possible, just enough to achieve that first period of 15 days above 135º F. I really like the simplicity of this method and will definitely use the turning sheet the next time I build a pile. I really makes it clear when you should turn and how often.

Moisture
Lack of moisture, according to Bakx, is the number one mistake made by beginning composters. He suggested an ideal moisture range between 40-­‐60%. You can check the moisture level using the following technique:

Take handful of material. Squeeze firmly
Water escapes: >60%
Shiny ball: 55%–60%
Ball remains when tapped: 50–55%
Ball falls apart when tapped: 45–50%
No ball forms: 40–45%
Unless hand feels powdery dry: <40 p="p">

Bakx has drip irrigation set up on his large windrows, something I might try with my pile the next time.

Pile Size
The mimimum size for a compost pile is 3 x 3 x 3 feet or larger.

Things not to add

  • Ash–our soils tend to be alkaline in California and ash will raise pH. A small amount is ok.
  • Cardboard–Bakx is afraid of the glues and said that he is very conservative about what he ads to his compost.
  • Toilet paper–because of metals (I’ve been unable to verify this–if any of you know about this issue, please leave a comment.

Alleopathic plant material such as eucalyptus leaves and walnut leaves, on the other hand, are ok to add. Bakx cited studies where plants were successfully grown in leaf litter made entirely out of eucalyptus leaves. He suggested keeping such alleopathic material to less than 15% of the pile.

Web links
Sonoma Compost’s website: www.sonomacompost.com
Sonoma Compost’s Simple Guidelines to Composting (pdf)
Sonoma Compost’s Temperature/Turning Sheet (pdf)
An online carbon/nitrogen ratio calculator

Comopost, Compost, Compost

As if I didn’t need a reminder of how important compost is to a vegetable garden, note the tomato above. It’s on its way out, but it grew with no supplemental water in hard-packed clay soil contaminated with lead and zinc in a hot side yard. Why did it do well while the rest of my vegetable garden did not do as so good this summer?

Homemade compost.

I didn’t have enough compost for the rest of the veggie garden so I bought some at a nursery. The homebrew compost obviously had much more life in it. 

And life is the point. Soil is a living thing. Plants, particularly vegetables, need microbial life to thrive.

For more on the importance of microbial life read the USDA’s soil biology primer written by Dr. Elaine Ingham.

Does the scent of compost make bees angry?

I think I’ve stumbled upon a strange phenomenon: the smell released by turning compost pisses off bees. Yesterday was the third time this has happened to me. I took a sting just underneath my eye and another one to my right hand when I was turning a pile located about 15 feet away from a hive. Coincidentally, the same thing happened to a friend yesterday: he got stung while working with compost near a hive. Ordinarily our bees are reasonable about living in a small yard with humans–they are not even very aggressive when I open their hive. But apparently turning compost near them is a different matter.

I look like I’ve been in a fight. Lots of Benadryl today.

I have a theory. Bees are incredibly sensitive to odors and use them to communicate. Their alarm pheromones alert the hive to predators such as bears and people. Bee alarm pheromone consists of many different compounds. Interestingly, a lot of these compounds such as n-Butanol and Isoamyl acetate are byproducts of fermentation processes. I’m guessing that a number of these compounds are present in compost, and that when you turn a pile the act releases a cloud of compounds that mimic the bee’s alarm pheromones, causing them to attack.

It turns out that other lifeforms like to mimic honeybee alarm pheromone. Some species of orchids mimic bee alarm pheromone in order to attract pollination services. Small hive beetles, who raid beehives for their pollen, apparently bring with them a yeast that causes a fermentation process that mimics alarm pheromones. The small hive beetle’s fermented alarm pheromone, in turn, attracts more small hive beetles who quickly overwhelm the hive. These sorts of deceptive, symbiotic and parasitic loops in nature really amaze me. 

As a side note, I’ve only had compost pile related bee stings at this time of year, when honeybee numbers are at their peak and pollen and nectar sources are getting scarce (summer is hot and dry in Los Angeles and not much is blooming).

If you don’t have a hive, I doubt random, foraging worker bees would go after you if you are just turning compost in your yard. But if you’ve got a compost pile and are thinking about installing a hive–or vice versa–I’d seriously consider keeping the two as far apart as possible.

Am I alone in noticing this compost/bee alarm pheromone issue?