Soil Foodweb Inc.
Dr. Elaine Ingham

Thermal Compost
10 Steps To Making Thermal Compost

1.  Decide on the Container for the Pile
For Example:
a. Hardware cloth with reasonably large opening.
b.  Stacking plastic tubs with the bottom cut out, lots of holes drilled in the sides and top.
c.  Three wooden slat bins-in-a-row.
c.  A pile on ground compacted down so rainfall runs off into a pond.
d.  All piles must be able to be covered to protect them from rain, snow, sleet, and evaporation.

2.  Collect Starting Materials
       a.  Store starting materials dry if you collect over time.
b.  Collect tiny bits of fungi from natural ecosystems and add to the middle of the wood chip pile where moisture is adequate to      enhance fungal diversity and biomass.
c.  The last thing to collect would be the High Nitrogen (N) so it can be used fresh.
d.  Use of cow, horse, and sheep manure may require slightly more than 10% High N, especially if you have to guesstimate how
     much bedding material is mixed into the manure and urine.
e.  Chicken, pig, and human manure is generally much higher N because they eat much higher N content food. Be careful not to
     over-apply these very high N materials.
f.  High Nitrogen (N) = FRESH manure (guesstimate woody component if sawdust or wood chips were used too soak up the
     manure and urine), legumes, germ of seeds, meat. C:N around 10.
g.  Green = anything cut when it was green and still contains the sugars, proteins, and carbohydrates; must be dried in order to
     store. C:N between 30 and 60.
h.  Woody = wood (chips are better than sawdust), stalks, paper, cardboard, anything high in cellulose and lignin. Enhance
     beneficial fungi during storage. C:N above 60.

3.  Determine Percentages of High N, Green, Woody
a.  Make trial piles. For Example: 50% of your mix of green, 50% of your mix of woody, split into 3 small piles, and add 10% High
     N to the first, 15% High N to the second, and 20% High N to the third. Monitor piles as described below to figure out how much
     of your High N is needed to maintain temperatures above 131F for the full 15 days.
b.  Measure the three starting materials using buckets (e.g., pails or front-end loader), or measure depth in the compost bin you      use.
c.  Once measured, mix materials together on a tarp, or mix layers in the compost bin by turning.
d.  Wet up dry materials: Soaking in water the day before starting the piles, or soaking overnight before starting the pile
e. Moisture of starting materials should be 50%, and piles should be maintained at 50%. Moisture must be tested by hand

4.  Decide on Compost Recipe
a.  Recipes for compost depend on how fast you want compost made and how much time you are willing to give to monitoring the
b.  Typical Small Scale, Fungal Compost Recipe: 10% High Nitrogen, 30% Green Plant Materials, 60% Woody Materials.
     Generally takes 6 to 8 weeks to finish.
c.  Typical Small Scale, Balanced Fungal:Bacterial Compost Recipe: 10% High Nitrogen, 40% Green Plant Materials, 50%
        Woody Materials. Generally takes 6 to 8 weeks to finish, unless compost tea with great fungal biomass is added at the
d.  Commercial Compost Recipe: 25% High Nitrogen, 30% Green Plant Materials, 45% Woody Materials (Please note this will
     need to be tested for temperature approximately every 6 hours during the first 10 to 15 days, and turned if necessary). This
     generally takes 4 to 8 weeks.
e.  Household Food Waste Compost Recipe: Put a pile of 50% Green and 50% Woody Materials together. Deposit the first
     increment of household waste about 1 foot from the bottom of this pile, but fully 2 feet into the pile. Make sure to completely
     cover and protect the waste put into the pile. Mark deposit site with a flag. Repeat each time food waste needs to be
     deposited, but move about a foot around the pile at that 1 foot from the ground level until all sites are occupied. Move up
     about 1 foot, and repeat deposits at this level until all sites are used, moving up and repeating until all sites are used. Wait at
       least 2 weeks after the final deposit is made at the top of the pile, then add the 10% High N needed to start the composting
       operation. Turn, mixing all materials well. Proceed to compost as normal.

5.  Temperature
a.  How often the temperature of the pile is taken is based on how fast the pile is heating.
b.  In compost that takes 6 to 8 weeks or longer, temperatures are typically taken each morning during the time the pile is above
     131 F.
c.  Always push the 3 or 4 foot long STAINLESS STEEL thermometer to the same depth each time to more accurately measure
     what is going on in the pile. If you very depth of your readings, the differences in temperatures may just be because you are
     deeper into the pile, and therefore hotter, or not as far into the pile, and therefore cooler.
d.  Always take at least three readings from each pile each time you measure temperature to understand hot/cold spots.
e.  The pile needs to get to above 131 F (55 C) within 3 to 7 days from starting. The pile must maintain temperature above 131 F
     for a full 10-15 days.
f.  Turn the pile when it starts to reach 160-165 F as the organisms are growing so fast that they are using up all the oxygen in
     the pile.
g,  Turn the pile if a layer of white ashy actinobacteria begin to develop.
h.  Turn the pile if there are wet and cold spots, or wet and dry spots. The pile needs to be reasonably uniform at the same
          depths in the pile.
i. Turn the pile if there are any bad smells noted.

6.  Moisture
a.  Measure moisture while waiting for the thermometer to come to equilibrium
b.  Pile should be maintained at 50% moisture. Anything over 50% needs to be dealt with immediately. 40% is okay, 30% is too
c.  Add moisture when the pile is turned. Thus, if moisture is approaching 40%, get ready to turn, and add water as turning the
     next day.

7.  Smells
a.  No bad smells should ever be detected.
b.  Turn the pile if even the smallest whiff of a bad smell is detected.
c.  Bad Smells: Ammonia, rotten eggs, sulfur, vinegar, sour milk, vomit, decaying flesh, or any mixture of these things.
d.  Do not let the pile become anaerobic or all the soluble, plant available N, P, and S will be lost as gases.
e.  Alcohol is made when anaerobic conditions occur, and if temperatures reach 180 F, the pile may spontaneously burst into
     flames. It is very important to measure temperature and moisture each day, or more often, if the pile is heating rapidly.

8.  Covers
a.  Cover the pile to protect it in stormy weather (rain, snow, sleet, etc.) or in dry weather.
b.  Covers can be made of felt fabrics that allow gases to diffuse through, but sheds 80% of water hitting the surface (best).
     However, tarps, butcher paper, space blankets, and even black plastic can be used.
c. DO NOT SEAL the bottom edge of the cover with dirt or rocks on the ground. The bottom fourth of the pile should be left
     uncovered so the pile can continue to get air in under that edge. Rocks or pins should go into the pile itself, not the ground.
     Aeration is critical.

9.  Notes About Turning
a.  A properly made pile should only require 5 turns, and then the temperature will start to drop to ambient temperature rapidly.
     For home use, turn the pile the least number of times you can, without allowing anaerobic conditions to begin.
b.  The initial mix of starting materials must be balanced correctly, to cause the organisms to grow rapidly, but not too rapidly.
     The amount of High N added is the real driving variable in that determination.

10.  Mature / Finished Piles: A pile is NOT FINISHED until temperature returns to ambient.
a.  Compost from a pile with temperature more than 10 degrees above outside temperature can harm plants, because bacteria
     and fungi are still growing so fast that they will out-compete the plant for nutrients.
b.  A mature pile will balance bacterial and fungal growth with protozoa, beneficial nematodes, microarthropods. In the case of a
     worm bin -- earthworms, predation, making sure that nutrient uptake is balanced by release.
c.  Bacteria are enhanced by turning, and they bloom to high numbers after turning.
d.  Fungi will be sliced and diced each time the pile is turned, and will need time to recover. The time between the fifth turn and
     when the temperature returns to ambient is critical for the fungi to balance bacterial biomass. So the final compost has a
     balanced fungal to bacterial ratio based on the woody and green components initially used when started.
e.  Protozoa, nematodes and microarthropods re-activate during the maturation period, and become more active.  
f.   When the pile reaches ambient conditions, diversity actually will continue to improve for the next 6 months.
g.  After 6 months, some foods will be depleted and diversity will begin to fall off.
h.  Maintain activity in the pile by adding foods for the organisms to start to become rare when using the microscope to assess
     the organisms.
i.  Maintain moisture above 30% and maintain good aerobic conditions.

More Information About Composting

Why not add the fungi are the end, after heating and turning? You can't make sure then that selection for just beneficial fungi has occurred, when you add something after all the important parts of the process are over. The fungi need to grow WITH the bacteria. Remember, we get rid of the bad guys in a thermal compost by reaching hot enough, long enough temperatures as well as by having the competition for foods, spaces, etc. We can't build structure in the pile to allow normal oxygen movement through the pile without fungi building macroaggrates right from the beginning.

So just turn to the least amount possible, by controlling the high N put into the pile. The high N is probably the most expensive thing that goes into that pile, so don't over-do on that part. Just enough, not too much, not too little.

Please realize that mycorrhizal fungi DO NOT GROW IN COMPOST PILES AT ALL. if anyone says they do, ask them to show data. We don't know how to grow mycorrhizal fungi outside of the root- fungus interface. No living roots in compost, no actively-growing mycorrhrizal fungi. Spores, yes. Hyphae, no. to increase the number of spores, you have to add an inoculum you know is pathogen-free --- so lab grown, or from a place in the real world where you can be pretty sure there are no disease or pest organisms. and you are taking a chance when you assume a place is disease / pest-free without testing it.

You CANNOT be constantly adding materials laden with human pathogens to a pile, never reaching temperature, and say you are making compost. Decomposed food waste, yes, but not compost.

So, how should this be done?

Two choices: 1. Worm composting. 2. Partial static - thermal composting.

Let's go through a part- thermal composting - part static composting scheme, which works and serves those who want to do thermal, but have daily to weekly inputs of food waste they need to deal with.

Get a pile of the green - woody mix (green waste, as bad-stuff free as you can get it). The first load of food waste should go into the pile about a food or two above ground level. The wetter the food waste is, the higher the deposit should be above the level of the ground. We can't have human pathogens moving into the soil below the ground through leaching of water from the food waste. You MUST assume any organic matter touched by human hands is contaminated by human pathogens. Therefore, at least one foot above ground level is fairly dry, two feet of sloppy.

The deposit should be at least 2 feet into the pile, so any odors that develop form the not-completely aerobic

Decomposition that might happen will be taken up within the pile and not escape. Can't have our N, S, or P escaping from the pile, so the organisms in the aerobic parts to the side and above the deposit must grab those nutrients before they leave the pile.

And, if those odors leave the pile they attract: any sort of fly, wasps, and any meat-eating vermin or predatory animal. They will dig into the pile to find what --- to them -- is making those delicious odors, and then spread your garbage all over the neighborhood. Your neighbors will never let you forget what happened (the morning I found used paper plates, napkins, ...... spread all over my yard) and might even make laws to prevent composting in the neighborhood.

So check your pile all the time for odors. If you smell bad odors, even the slightest bad odor, add another foot thick layers to the top of the pile, or enough of a layer that no bad smells will be detected.

The second deposit of food waste goes into the pile at the same height, same depth, but a little bit over from deposit #1. Far enough over that you aren't digging up any part of deposit #1, but not too far over that you are not using all the space you can in the pile. The third deposit is same as #2, except a bit further along the pile.

Once all deposit sites are filled on the lowest level of the pile --- I usually put little flags in the pile to note where a deposit site has been filled so I don't accidentally uncover the slightly putrid spots of previous food waste, then I move up a foot, and fill the spots at that next level. Continue until all possible deposit sites are filled. the last deposit is at the top of the pile, straight down into the center of the pile. You are now finished with adding any food to this pile. Wait at least two weeks (maybe longer if you compost through freezing temperatures). Then add 10% high nitrogen to the pile and mix that in.

Now you do the typical thermal composting process, making sure that ALL PARTS of the pile get into the hot middle area, thus killing all the human pathogens. Temperature MUST be measured each day during the 10 to 15 days the pile will be hot. Not hot enough long enough ..... start over.

You can probably see some variations on this method, depending on the pile configuration you like best, and the height you can mange (I can't have piles anything about 4.5 feet, my back just won't take it anymore).

Of course, I give more details in the on-line course, so this is to just get you started doing things so it will be real compost, no pathogens, once you finish.

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