10 Steps To Making Thermal Compost
1. DECIDE ON THE CONTAINER FOR THE PILE
- Hardware cloth with reasonably large opening.
- Stacking plastic tubs with the bottom cut out, lots of holes drilled in the sides and top.
- Three wooden slat bins-in-a-row.
- A pile on ground compacted down so rainfall runs off into a pond.
- All piles must be able to be covered to protect them from rain, snow, sleet, and evaporation.
2. COLLECT STARTING MATERIALS
- Store starting materials dry if you collect over time.
- Collect tiny bits of fungi from natural ecosystems and add to the middle of the wood chip pile where moisture is adequate toenhance fungal diversity and biomass.
- The last thing to collect would be the High Nitrogen (N) so it can be used fresh.
- 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.
- 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.
- 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.
- 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.
- 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
- 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 method
4. DECIDE ON COMPOST RECIPE
- Recipes for compost depend on how fast you want compost made and how much time you are willing to give to monitoring the
- Typical Small Scale, Fungal Compost Recipe: 10% High Nitrogen, 30% Green Plant Materials, 60% Woody Materials.
Generally takes 6 to 8 weeks to finish.
- 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
- 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.
- 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.
- How often the temperature of the pile is taken is based on how fast the pile is heating.
- In compost that takes 6 to 8 weeks or longer, temperatures are typically taken each morning during the time the pile is above
- 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.
- Always take at least three readings from each pile each time you measure temperature to understand hot/cold spots.
- 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.
- 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
- Turn the pile if a layer of white ashy actinobacteria begin to develop.
- 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.
- Turn the pile if there are any bad smells noted.
- Measure moisture while waiting for the thermometer to come to equilibrium
- Pile should be maintained at 50% moisture. Anything over 50% needs to be dealt with immediately. 40% is okay, 30% is too
- Add moisture when the pile is turned. Thus, if moisture is approaching 40%, get ready to turn, and add water as turning the
- No bad smells should ever be detected.
- Turn the pile if even the smallest whiff of a bad smell is detected.
- Bad Smells: Ammonia, rotten eggs, sulfur, vinegar, sour milk, vomit, decaying flesh, or any mixture of these things.
- Do not let the pile become anaerobic or all the soluble, plant available N, P, and S will be lost as gases.
- 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.
- Cover the pile to protect it in stormy weather (rain, snow, sleet, etc.) or in dry weather.
- 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.
- 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 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.
- 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. FINISHED PILES
A pile is NOT FINISHED until temperature returns to ambient.
- 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.
- 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.
- Bacteria are enhanced by turning, and they bloom to high numbers after turning.
- 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.
- Protozoa, nematodes and microarthropods re-activate during the maturation period, and become more active.
- When the pile reaches ambient conditions, diversity actually will continue to improve for the next 6 months.
- After 6 months, some foods will be depleted and diversity will begin to fall off.
- Maintain activity in the pile by adding foods for the organisms to start to become rare when using the microscope to assess
- Maintain moisture above 30% and maintain good aerobic conditions.