TrolleyDriver's Compost Thermometer

sanderson wrote:Yes, it did drift away and I am partly the blame for not corralling it sooner.  I may split off some of the replies to another thread when I have more time to concentrate.

Okay ... sorry about that. It still is about monitoring the compost temp with my simple digital refrigerator thermometer although I drifted into things like turning the compost. BTW now up about 6 degrees Celsius since turning it about 4 hours ago. But I'm wondering if that isn't mainly residual heat that was left in the materials prior to turning. Will have to see if the heat loving microbes can take control.

FWIW ... the thermometer is reading 39.2C (102.6 F) as of 8:30 am. which is about 21 hours after turning. It's not yet into the thermophilic range above 40C but very close. After today the ambient temperatures are going to be much lower so with this small pile there could be considerable heat loss to the atmosphere.

trolleydriver wrote:FWIW ... the thermometer is reading 39.2C (102.6 F) as of 8:30 am. which is about 21 hours after turning. It's not yet into the thermophilic range above 40C but very close. After today the ambient temperatures are going to be much lower so with this small pile there could be considerable heat loss to the atmosphere.

Well it looks like I killed it. The temperature is down to 35C and not rising. I may have to rebuild the pile or just leave it to cold compost.

If it's an undersized pile, it may not heat up to the high temps again. I'm predicting that it will turn into some nice compost come spring.

sanderson wrote:If it's an undersized pile, it may not heat up to the high temps again.  I'm predicting that it will turn into some nice compost come spring.

Totally agreed on all points. Temp is 37.7C this morning.

I really need to make a bigger bin especially since there will be a ton of things to compost as we clean up the veggie and flower gardens and get leaves from the neighbours.

trolleydriver wrote:

sanderson wrote:If it's an undersized pile, it may not heat up to the high temps again.  I'm predicting that it will turn into some nice compost come spring.

Totally agreed on all points. Temp is 37.7C this morning.

I really need to make a bigger bin especially since there will be a ton of things to compost as we clean up the veggie and flower gardens and get leaves from the neighbours.

As an interim measure I have added fresh lawn clippings (grass, clover, weeds), straw, etc. and have brought the level up to the top of the bin. There's a layer of straw on top for no real reason. Now will monitor temps again to see what happens.  The tomato, tomatillo and ground cherry plants beside and behind the bin are very healthy. BTW this compost bin gets high marks in reviews on Amazon.

Is the pile moist enough?

yolos wrote:Is the pile moist enough?

I believe it is. It was quite damp already and when I added the new straw I made sure I watered it down. The grass clippings were already damp. I mixed the grass and other things with the straw layers to help prevent clumping of the grass. The top covering of straw was not watered down (no reason why).

This morning at 8 am the temperature reading was 43.5C (110F) which means it has moved into the low end of the thermophilic range. Overnight ambient temperatures will be going down to 3C (37F) for the next few nights which probably will result in heat loss in this relatively small pile.

Anyway, whatever happens with the compost pile, it's fun to play with and to monitor it.

I get so excited about this compost stuff (I know ... that is so pathetic) that I have to go out every few hours and check the temperature.  Three hours after the earlier reading the temp has gone from 43.5 to 45C.  I like what is happening.

After 25 hours the temp has reached 47C (116.6 F). That's a rise of 3.5C in the past 8 hours. Hopefully by tomorrow it will be over 50C. The previous attempt topped out at 57C before starting to cool down but that was with much higher ambient temps than we have here today.

trolleydriver wrote:I get so excited about this compost stuff (I know ... that is so pathetic) that I have to go out every few hours and check the temperature.  Three hours after the earlier reading the temp has gone from 43.5 to 45C.  I like what is happening.

TD, you're not alone in your quest for composting. I enjoy the composting more than gardening itself, so much that I am fairly close to sending for a microscope. Only reason I do not have it now ? I want to make certain I will use it.
This book in case you're not aware will explain everything that goes on inside the piles and much more.

My bin has been 155F for at least 2 days this week.  I love when it cooks!  It's hotter than... 

jimmy cee wrote:

trolleydriver wrote:I get so excited about this compost stuff (I know ... that is so pathetic) that I have to go out every few hours and check the temperature.  Three hours after the earlier reading the temp has gone from 43.5 to 45C.  I like what is happening.

TD, you're not alone in your quest for composting. I enjoy the composting more than gardening itself, so much that I am fairly close to sending for a microscope. Only reason I do not have it now ? I want to make certain I will use it.
This book in case you're not aware will explain everything that goes on inside the piles and much more.

Jimmy ... Last Spring I borrowed the book from my local library.  It was a good read.

trolleydriver wrote:After 25 hours the temp has reached 47C (116.6 F). That's a rise of 3.5C in the past 8 hours. Hopefully by tomorrow it will be over 50C. The previous attempt topped out at 57C before starting to cool down but that was with much higher ambient temps than we have here today.

Success. At about 8 am the temp is 50.2 C.  Outdoor temp is about 7C (45F) and was lower during the night.

I turned my pile 2 days ago and inserted a SS rod deep within. Today, I pulled the rod out and was not able to hold onto the middle, that indicated to me a temperature of 145 and up. I do like that electronic readout. If only I can make it a wireless signal and have a readout in the house...Maybe even hook up a 24 hour recorder to monitor temps.

Very cold here overnight ... even got some frost. The compost temperature has dropped from a high of 50.8 yesterday afternoon to 49.8 at 8 am this morning. Another cold night coming today as well.

Cold again overnight.  Compost temperature is down to 46.8C.

Here are a couple of graphs I found on the Web which show the effects of pile volume and turning frequency. My pile is only about 12 cubic feet and my max temp was about 123F which is about right according to the graph. Going to a 3x3x3 (27 cubic feet) provides a significant increase in max temperature (as we already knew) and duration of max temperature. I really need to get that 3x3x3 built and hopefully test it before winter. I'll have plenty of greens (plants from the gardens) as well browns (leaves) to throw into it soon. 

Rings pretty true. Twenty (20) days of high temps with frequent turning. Turning reintroduces oxygen and allows frequent checks of moisture.

Now that my camera is working again (after I mcGyvered a solution) I will be able to drive everyone crazy with more photos.


This morning's compost temperature reading after a bit of a stirring up in the compost bin yesterday shows it in the thermophilic range.

Do I understand correctly, that every time you add oxygen, the temp goes back up?

It will do so long as there is also well moist decaying food for the fungi , bacteria & bugs to feed upon as well .  For it is the latter three things that produce the heat as they consume the goodies( convert the energy )  released by the newly oxygenated pile.
Differing stages of composting decay in the heap also release /produce  different chemicals & nutrients.   It's like   an amazing chemical factory production line process .
As the availability of decaying material reduces in the pile , over a long time the amount of heat released will gently reduce no matter how much you turn it ( so long as you don't add more new compostable matter ) . Reducing at one point to something not very noticeable without specialist test equipment  .. 

We need our heaps to be about 1/2  finished at that state as it gives us all the trace nutrients needed there & then for plants  , plus some matter still to decay to give a continual slow release of more nutrients . 
This is to replace those nutrients & trace chemicals the plants are using up quickly .

trolleydriver wrote:

trolleydriver wrote:

sanderson wrote:If it's an undersized pile, it may not heat up to the high temps again.  I'm predicting that it will turn into some nice compost come spring.

Totally agreed on all points. Temp is 37.7C this morning.

I really need to make a bigger bin especially since there will be a ton of things to compost as we clean up the veggie and flower gardens and get leaves from the neighbours.

As an interim measure I have added fresh lawn clippings (grass, clover, weeds), straw, etc. and have brought the level up to the top of the bin. There's a layer of straw on top for no real reason. Now will monitor temps again to see what happens.  The tomato, tomatillo and ground cherry plants beside and behind the bin are very healthy. BTW this compost bin gets high marks in reviews on Amazon.

  That's a decent bin TD ,
Do you use a long pointed stick /rod or bar to poke a few holes deep down through the bin and then give each hole a half gallon drink down each hole to help speed up the compost production ?

sanderson wrote:Do I understand correctly, that every time you add oxygen, the temp goes back up

As far as I recall, after turning or stirring up the pile it never went back up to the peak temperature. BTW I keep adding stuff to this pile so it's really not a true bulk hot composting pile. That's why I want to build another and bigger pile that will be my bulk pile.

plantoid wrote:

Do you use a long pointed stick /rod or bar to poke a few holes deep down through the bin and then give each hole a half gallon drink down each hole to help speed up the compost production ?

I use a broom handle and sometimes a 1"x2" piece of wood to poke holes but I have not poured water into the holes. I'll have to try adding water as you suggest. TKS

Yesterday I poked some holes into the compost pile, poured in some water, added some almost dry grass clippings and some leaves.

Drum roll please ...



Presenting a new record temperature for TD's Soilsaver compost bin. Last recorded temperature was 52.0 Celsius (125.6 F).