What is Compost?

Compost is an amazing material that permaculturalists prize worldwide.

Compost is defined as "a mixture that consists largely of decayed organic matter and is used for fertilizing and conditioning land" by Merriam-Webster.




Compost is the soil-like substance created through the process of breaking down organic substances through bacterial, microbial and fungal processes. Compost is a method of speeding up decomposition in a controlled way. Compost can be created with a wide variety of materials including garden trimmings, kitchen waste, animal manures, deadstock, and many other things. In order to make good quality compost in a reasonable time frame, it is the interest of the gardener to create a friendly environment for all of these microbes to process down the individual compost components down into a quality finished product. This is achieved through a balance of carbon rich materials and nitrogen rich materials intermixed in a pile with the addition of moisture.  As a  general rule, a good ratio of carbon material to nitrogenous material would be a 3:1 ratio by volume.




Hot Composting Phases
Under ideal conditions, three different phases of decomposition can be seen in a hot compost pile. (Hot composting is not the only way to compost but it is common.)
1. Mesophilic Phase - This is the initial phase of decomposition where mesophilic microbes begin to break down base materials to start the composting process. This is a 'cool' phase where temperatures just start to build up in the pile.
2. Thermophilic Phase - This advanced phase of decomposition begins when the pile temperature rises to around 130 degrees F and thermophilic bacteria begin to populate the pile replacing mesophilic bacterial who cannot thrive in the higher levels of heat. Reaching this stage assists in destroying pathogens that could be detrimental to both the gardener and plants due to the high heat being a hostile environment for the nasty pathogens.
3. Maturation - As the original feedstock for the compost is broken down and there is not enough to support the population of thermophilic bacteria, the pile cools and the microbial population decreases over time leaving a nutrient rich material that is beneficial for plants.

The composting bacteria mentioned prior are really amazing in the composting process. They take complex organic materials and break them down into simpler compounds. This process generates as byproducts both heat and creates a compound known as humus. The simple compounds are better available to plants to uptake as nutrients and to enhance their growth.

Benefits of Compost
1. Compost provides a source of nutrients for plants to grow over a growing season. While compost nutrient makeups can vary based on feedstocks, it is common to see an NPK of 1-1-1 from finished composts. Composts are not a concentrated instantly available fertilizer but rather a slow release nutritional material.
2. Compost improves the properties of soil to increase permeability, hold moisture, and increase organic matter.
3. Compost increases a soils CEC Cation Exchange Capability .
4. Compost stabilizes and buffers soil PH.
5. Compost can reduce soil erosion.
6. Compost presents an alternative path for items that may traditionally end up in conventional waste streams. Compost can divert up to 60% of household waste from trash bins.

Detriments of Compost
1. Compost requires space to be produced. Some smaller homesteads might find this to be a challenge.
2. Depending on the materials being composted and technique, smell and pests could be an issue.
3. Many forms of composting involve physically turning over piles which take time and effort. This can be a limiting factor for some people.

Related Threads
Examples of Compost Piles
Sifting Compost
Composted vs Rotted

Tim's Book Recommendations on Compost
1. Compost Everything by David The Good
2. Let it Rot by Stu Campbell

There are many videos out on the internet on how to traditionally compost but one of the best experts, in my opinion, is Charles Dowding.

I'll admit it, I'm a lazy composter! The less effort I need to put into the process the better in my mind.

I keep both a hot (active) compost pile as well as a couple cold (passive) compost piles that are built and left to do what it does.




Anything that may have seeds, could attract pests (meat/bones), may have the potential for disease goes into a hot compost pile. My hot compost piles keep getting flipped and may get several additions to it as its processing down.

Everything else goes into passive piles that are made and left to their own devices.

I build my passive piles when I obtain enough browns and greens so that I can make the heap and not have to touch it after. It starts by making a nice thick (3") layer of brown materials on the ground followed by layers (2") of nitrogenous materials and carbon materials. I aim for a size of around 5'x5'x5' for a finished pile. I will then finish up the pile by covering it with a cap of carbon material in order to insulate the interior.

Over time, if the pile seems to have stalled out, I will flip the pile a couple times but not as frequently as my hot pile. After five to six months there should be an appreciable amount of compost that can be harvested and utilized for plants.

I'm also a lazy composter, but I've just watched through Dr. Elaine Ingham's presentations from Permaculture Voices 1 (which you can purchase as part of a large bundle here: https://permies.com/t/voices123) and am looking to learn more about her particular approach to composting for maximum microbial life diversity. I have these three videos queued up for this weekend:







(She won't call the humus that comes out the bottom of my cold compost piles compost because it doesn't have the right life in it.)

Lazy composter here too. Sometimes my piles get hot but that's not really a goal. I mostly look at the compost as something nice to have on hand when I need it but mostly for adding some organic material or even some quick potting soil when dug out from he bottom of the pile more than for adding good diverse life. I've always looked at it as you can't stop composting from happening. Can only slow it down or speed it up.

I maintain worm bins indoors all year and make sure they are diverse with life and usually fungal dominant. When I want to add life to new areas or some potting soils I use some of the castings and worms from the bins. This works wonders for me.

Not all types of compost are created equally.

There are a few different ways one could consider organizing all of the different composts but there is not a widely agreed way as far as I know. In lieu of an organizational standard, I find a running list may give some inspiration to new composters to explore further on their own.

Types of Compost
1. Hot Compost - Primarily Aerobic Compost
2. Cold Compost - Primarily Anaerobic Compost
3. Vermicompost - Compost created through the usage of worms.
4. Leaf Mould - Compost created with strictly leaves.
5. Mushroom Compost - Compost made from the byproducts of mushroom production.
6. Bokashi - Compost created through anaerobic fermentation.
7. Manure Compost- Compost made primarily of animal manure(s) and bedding.
8. Humanure Compost- Compost made from people's waste.

Not all composting systems are created equal.

Only some systems are intended to create harvestable compost that is to be utilized elsewhere. Instead, some systems are created to eliminate the need to handle the compost and instead benefit the immediate area around the compost system.

Composting Systems
1. Hot Compost Heap - Primarily aerobic compost to be harvested
2. Cold Compost Heap - Primarily anaerobic compost to be harvested
3. Keyhole Garden - A raised circular garden bed with a central composting pit.
4. Hugelkultur - A food system based on buried logs and organic material that creates fertile mounds to grow on.
5. Compost In Place - Putting organic matter directly into the soil via holes/trenches where you intend to grow plants.
6. Sheet Composting - Composting over an area to create fertile growing space.
7. Aerated Static Pile - A composting system involving air being forced into the pile.
8. Windrow Composting - A large scale aerobic compost system where compostables are heaped in long rows and usually turned with specialized machinery.
9. Johnson-Su No-Turn Composting Bioreactor/Static Pile Fungal Compost - A composting system utilizing vertical ventilation pipes to create fungally dominant compost.
10. Compost Tumbler - A spinnable container that simplifies the compost turning process.
11. Chicken Compost System- A system that utilizes chickens to turn and aerate compostables.

A usage of compost that deserves a dedicated post is compost tea.

Compost tea is the liquid extract of compost. It is full of microbes and soluble nutrients that can benefit soil health. Compost tea can be created with a process as simple as placing finished compost in a vessel of water, letting the material soak for a period of time and then separating the resultant compost tea from the solids. Compost teas can be used both as a foliar spray and a root drench depending on what the user desires. Compost tea is commonly diluted with water prior to application.

My understanding of compost tea is that a person can create a liquid rich with microbes that can then be spread over soil in order to inoculate it with all of the 'good stuff' we would expect from compost rich soil biomes. The idea is that this helps boost the diversity of the soil biota in order to benefit our growies.  Compost tea applied to plants can help deal with disease issues through the coating of microbes as well as benefit the plant through direct uptake of soluble nutrients through the plant's pores.

For an alternative type of compost tea, I am a fan of David the Good's compost tea recipe for Fetid Swamp Water!

No Rules Compost

There are many resources put out to help folks composting listing things that should not be composted and I am here to challenge that. If something rots, it can become a part of compost. All organic waste can be turned into nutrients for our plants.

No Rules Compost can include meat, bones, dairy, fats, weeds with seeds, cooked foods and more! The one rule to no-rules compost is to avoid anything that could potentially be contaminated with toxic gick. Maybe I should start calling it one rule compost? I digress...

I like to insulate the pile with a thick layer of carbon material on top and the sides to help maintain the heat in the center of the pile. I also believe it helps deal with any potential smell issues that could arise. If a smell does develop, it means that the pile needs to be turned and reassembled with the addition of carbon to balance out the releasing nitrogen.

Any compost is better than no compost at all.

Here are easy ways to make stuff happen.

https://permies.com/t/80/13602/Incredible-Amazing-Leaf-Mold

https://permies.com/t/281440/Weed-Soup-Compost-Tea-soil

https://permies.com/t/120453/Great-Wood-Chips

https://permies.com/t/98150/Build-abundance-chop-drop

https://permies.com/t/129642/overview-chop-drop-awesome

https://permies.com/t/25804/composting/Common-Sense-Compost-Making-Quick

Compost leachate is the liquid that drains from a compost pile as organic matter decomposes. Compost leachate is usually dark in color, full of nutrients and microbially rich. Leachate is different from compost tea because it is naturally draining from the compost instead of being 'brewed'. Depending on the amount of leachate generated, there are considerations that should thought about to best utilize this material.

Leachate CAN pose a runoff risk if a sufficient amount of liquid is generated in a pile (usually only seen with industrial scale composting) and left to disperse into the environment. Sensitive areas like waterways and groundwater could have negative effects if unmanaged leachate accumulates in those areas. This can be commonly managed through either capturing the leachate through usage of something like a drip tray or by moisture control/site management. It could be a simple as placing a nonpermeable cover over the pile if there will be heavy rains or as involved as intentionally planted buffer plants near the composting sites.




For my homestead level composting, I create my piles on top of a thick layer of carbon material (wood chips) in order to tie up and mitigate the liquid immediately. I'm a fan of planting comfrey nearby my composting area in order to take advantage of any runoff and turn it into biomass. I do not intentionally cover my piles with any impermeable barriers but I will cover my compost with carbon material. Essentially my compost piles are surrounded with either straw or fallen leaves to help insulate the pile.

Captured compost leachate can be utilized just like compost tea either as a root drench or a foliar spray. The mixture of microbes and nutrients can give a boost to growies that it is applied to. Commonly, it is recommended to dilute this liquid 1:10 to 1:20 parts leachate to water.


Related Threads
Leachate Control for Community Compost
Growing next to Compost Pile

I love it when two separate interests of mine collide where seperate systems start overlapping each other.

Let's talk about Chicken Composting Systems.

A chicken composting system places compost piles in areas accessible by chickens and utilizes them to build compost. Chickens will scratch and peck the pile, turning materials and help keeping the material aerated. They will help break down organic matter through mechanical action as well as deposit their own fertility into the mix. The chickens will be able to scavenge insects, seeds, and other edibles from the compost benefiting their diet.

It is common to create a shallow bay compost system. The raw compost inputs are placed in the first bay where the chickens can get to them. As it starts to break down, it is eventually moved to the next bay so new raw compost inputs can be inserted into the first bay. As the chickens scratch and the compost ages, the material is moved to further bays until you arrive to a finished product. While the chickens reduce a significant amount of time turning the compost, this still requires some effort. At the end, some utilizers of this system will sift the finished compost and return any unfinished material back into the composting process.

Sean from Edible Acres has developed his chicken compost system over the years. Check out some of his content below.

You are missing another system that looks like it has super promise.  Passive no turn aerobic composting.  I have kept meaning to get this write up copied over to permies but haven't done it.  Here is what looks like a complete path covering all the pieces I assembled a list of.  I encourage someone else to bring the information in.  Hate to link to FB but I can't move this any other way easily.

passive no turn aerobic composting.

Carbon is an important element when it comes to the creation of compost. Not all materials contain the same amount of carbon so becoming familiar with how different materials break down is important. Luckily for us, some really smart people have put together carbon to nitrogen ratios of many materials for us to better understand. It is generally accepted that the best ratio of carbon to nitrogen to create compost is 30 parts carbon to one part nitrogen. Creating a blend of materials to reach this magic ratio is part of all the fun of making compost.

Compost Ingredient C:N Ratios

Be aware, not all carbon material is easily broken down. Carbon that is part of complex substances such as lignin are resistant to the processes of biological breakdown. Note that they are not immune however! There are many types of fungus that happily break down lignin when allowed to establish undisturbed. When people make fungal dominant compost, they minimize disturbance to the pile and may actually desire to have a higher carbon content C:N ratio than traditional compost.

As the materials breakdown, the 30:1 ratio actually reduces to something more akin to 15:1. Carbon is lost through the process of microbial digestion as it is released in the form of carbon dioxide to the environment.

The opposing side to carbon is nitrogen (N2).




Nitrogen is like fuel for hot composting microbes. The more nitrogen available, the bigger the microbial population that is possible. Where plants cannot take advantage of nitrogen that is locked up in protein form, bacteria can. After a while without any additional compostable materials, a tipping point is hit and nitrogen starts to become scarce. The microbial population will die back and leave nutrients/minerals that plants find desirable in a more available form. It is important to not have too much nitrogen in a pile! With too much nitrogen, there is a chance that it will off-gas as ammonia (NH3) or runoff in the form of nitrate (NO3-). A simple way to tell if you have too much nitrogen in your pile is that your pile will stink. The easiest solution is to mix in and cover the pile with carbon rich materials.  

Finished compost does not have nitrogen levels like its raw ingredients. It will contain .5-3% nitrogen that is released over years as the nitrogen mineralizes into the inorganic forms of Ammonium (NH4+) and nitrate (nitrate NO3-) .

A lot of the previous discussions on the different microbes that break down organic matter has focused on mostly bacteria and some fungi. As with a lot of things, it is not that simple. There are a lot of creatures in play to help create compost.




A thriving compost biome will host primary, secondary, and tertiary consumers. Their presence can give you an indication on where your compost is in it's production cycle as well as potential conditions that may be present. By analysing what is in our compost, we can adjust our processes to make a high quality end product.

Actinomycetes are like a bacteria version of fungus. They create a white cobweb like network of hyphae that looks similar to mycelium development. Actinomycetes specialize in breaking down tough materials such as lignin and cellulose.

Nematodes are friends to composters. Instead of the parasitic nematodes that may hurt our growies, there are varieties of nematodes that help break down organic matter and benefit composting. They assist in recycling nutrients and maintaining a healthy biome.

Springtails are a delight to find in my compost. They consume organic matter (cellulose), fungi and mold with vigor. They also can indicate there is plenty of moisture if not excessive moisture in a pile if the springtail population explodes suddenly.

Mold mites are detritivores that enjoy chowing down on decaying organic matter. Their presence in high numbers can indicate excessive moisture and possibly compaction in your pile.

Rotifera are microscopic organisms present in water films that feed on bacteria, fungi, and organic matter. Rotifera are generally found in finished stable compost. Rotifera are sensitive to toxins so their presence is a welcome sign.

I do mostly hot composting. I build about 3-4 good piles a year, spring to fall, usually 4x4x3 feet. They get hot, sometimes 155f, that's too hot. I try to turn them every 3-5 days, but sometimes life gets in the way, and they don't get turned for a week or so. I utilize a couple of 3 ft 4 inch pvc drain pipes with more holes drilled into them, set vertically, to help get air into the center of the pile.  I also have some smaller diameter pvc pipes with lots of holes drilled in a circular pattern that I lay horizontal in the pile to bring in air.

I also do compost in place in my veg beds after the growing season is over, and if I don't have winter cover crops growing in those beds. I'll prep the beds in the fall and cover them with mulch, and then I'll sneak kitchen scraps under the mulch right up till the winter weather makes it not fun. By spring most of the scraps and coffee grounds have been consumed by microbes and worms.

I am going to try a new thing this coming spring's growing season. There's a concept called "core gardening", apparently done in Africa somewhere that get's a lot of rain in winter/spring, but droughts in summer. They burry reeds in their garden beds a foot or so down, and as the winter rains soak the beds the reed material absorbs the water and starts to rot and also becomes a sponge that hydrates the beds during drought. There's a guy in Michigan, I'll post the video below, that does this with hay or straw. I want to do this because of increasingly reoccurring 6-8 week long droughts in my area, usually in late May-June, or June-July. I hate watering my rather large veg garden, and don't like the idea of setting up irrigation. I would use the straw method, but I can't trust that the straw I would have to buy wasn't sprayed with some forever chemical, and while I grow winter rye for mulch, I can't grow enough to burry for a core. So I'm going to try my own version of this using 1 part my compost, 1 part biochar that I make and inoculate, and 1 part pumice stone that's about 1/8-1/4 inch stones. I mix these together and use that as the core of my beds. This should hold more moisture than the surrounding soil, so in the event of an extended drought the plants can access this moisture. Also I won't have any nitrogen tied up breaking down the straw, since I'll be using inoculated biochar and compost. The pumice is inert, so that acts as a sponge and a home for microbes to hold up, just like biochar.

Just to confuse matters, there's potting compost and rotting compost. The latter's what's being discussed above. Potting compost can include some of that, along with material with less fertility - sand, loam, leafmould.

Many (so-called) gardeners ditch their compostables in green wheelie-bins taken by the council, or worse, in the ditch across the road.
They're
* losing fertility, that they'll have to buy back in bags from the garden centre. And they're using fuel - for the collection vehicle, the composting process, and the garden centre trip
* the energy stored in the plants from summer is leaving their plot, while kept on site it can feed a whole chain of creatures, aiding biodiversity, including the birds they love to see.

What is a compost pile without a little urine?



Urine is the perfect addition to the compost pile providing a shot of nitrogen to help keep hot piles functioning at their best potential. Urine provides a Nitrogen-Phosphorus-Potassium (NPK) profile of around 11-2-4. The nitrogen profile of urine is mostly in the form of urea with a smaller amount being ammonia. Human's do not fully utilize all of the nutrients of the foodstuffs that they consume and eventually excrete the excess. We can take advantage of that excess and cycle it back into growies that we cultivate.

There is a common misconception that urine is sterile but there in fact exists an entire biome of microbes found in urine. For the 'average' person, these microbes are not something that they should be worried about with common sense handling. The story I have read about is that back-in-the-day urine tests for bacteria/viruses did not test at the low population levels that healthy urine has so it was considered sterile. Modern testing has now challenged that finding and shown that microbes do in fact exist.

Utilizing urine in the compost can come in several forms. Urine can be added directly, stored and accumulated in a container before being added, or mixed with carbon-rich materials before added to a pile. An example of the last way is to fill a bucket with sawdust and to add urine to it until it is full. The bucket is then emptied and refilled with carbon rich material. This pee-cycling removes urine from traditional waste handling systems in the home and upcycles it to create good quality compost.

According to the Rich Earth Institute, one person's urine output for a year contains enough nutrients to grow three hundred and twenty pounds of wheat.

For a deeper dive, I recommend folks check out The Humanure Handbook by Joseph Jenkins where he addresses common concerns folks have about the usage of urine (and humanure) in the composting process. Prior to reading this book, I was hesitant to use urine but the author does an incredible job really fleshing out why it is a useful and safe component when utilized appropriately.

Thank you for that addition Timothy!
I feel joy every time I donate some nitrogen to my compost piles in the garden.
The Humanure Handbook is such a good book, can't recommend it enough. It's also free to read if you want to. So basically no excuse, except not liking Jenkin's humor.