Humus is simply another name for what compost is, organic matter. If your material is being digested and converted from what you put in to compost you are doing it right and need not worry as much as you apparently are. Keep it up.

There's a lot of opinions about the best way to compost, but the most important test is whether it's right for the person who has to do it - so if it's working for you, it's working. There's nothing wrong with doing cold composting. In my view, any discussion of nutrient content takes a back seat to having a process that suits your needs.

As for your question: brown matter has a few different roles. One is helping create conditions for hot compost (the mix of materials that the right microbes for this prefer); part of that is the energy in the carbon-rich materials or browns those thermophilic microbes like and need. Another role is that drier browns tend to have a bit more physical structure and can absorb some water - that helps avoid the anaerobic smelly pile issues (but since you've found another way to avoid wet anaerobic conditions that works for you, don't worry about it). Another role is that browns will have more components like lignin and cellulose that decompose more slowly and tend to form part of the organic part of the soil that is 'stable' (roughly speaking, not actively decomposing, or only slowly); but that's a question of degrees and conditions, too.

While I think this is interesting stuff and important biologically, it doesn't follow that you need to add more browns or worry about not having them. If you have enough compost now and you're happy with the results in your garden, stick with it.

I'd go so far as to say if you do come across a bunch of browns someday, keep your current process going separately since it works; experiment/test how composting the browns works since a different process may not work for you.

kimmq: Both Humus and compost are good. However, I have found some difference between the two, partly based on what I've read and partly based on my experience.

Humus holds more nutrients but seems to dissolve more quickly. Compost is a topsoil builder which decomposes and releases nutrients more slowly, which means less nutrients are leached out.

My experience is that humus alone, after being consumed, leaves a soil which is prone to compacting. I have done that in the past and I had to "break" the soil by hitting hard with the shovel. When I mixed the topsoil with compost, the soil remained "soft" or aerated for longer. I have even seen more micorrhizal activity (that white stuff). That's why I apply compost into the soil, and add humus on top of it.

What humus are you buying? Again, whatever works, if you're happy with it, etc. But I doubt anyone can get specific about what your humus is like nor especially its nutrient content or how it behaves in your garden. In general humus is basically a finished compost, whatever nutrient or other qualities it may have, so not much of a comment on what you may have. I wouldn't assume your compost has fewer nutrients, unless you've got actual testing results (or have some humus that's been enriched with nutrients).

I'm pretty sure what I buy is worm casts - at-least that what it says on the label. The compost in my garden is what comes-out from a compost pile without worms, including the thermophillic process. I don't have composting worms, and soil earthworms do not migrate into the pile.

If what you are doing is turning the waste into gold.. keep doing it.

I usually have a goodly amount of dried leaves around here... but sometimes I got more weeds and greens and tapped out on the browns. I just layer on the greens and let them die off and dry up before adding more on top. I don't make fast piles, but they break down well enough and don't get smelly.

@asclepiad - worm castings can be great, if you're happy with it, by all means (whether they're 'humus' per se or something different - only a terminology issue). I've had in the past and indeed it tends to be fairly fine-grained, and can have a tendency to dry out if applied alone.

Armoured stated it far better than I can so I'll just say I agree,esp about keep doing as you have and experiment with other methods. It's hard to imagine a household where no browns are available. Cereal boxes,paper towels,non-glossy paper,FedX shipping boxes to name a few. The supply is endless outside the home and around the neighborhood fall leaves being the most abundant. I can't see how buying humus contribute's.

From Dictionary.com, "noun

1. the dark organic material in soils, produced by the decomposition of vegetable or animal matter and essential to the fertility of the earth."

There are a number of articles out there that purport to differentiate between humus and other organic matter, but they are the same thing.

Just keep doing what you have been doing since your material is turning into compost.

Most all of the nutrients in any green material put into compost will still be there in the brown material that comes out. The only nutrients that escape would be the same ones that would escape if green material was turned in the soil.

From what I can gather, scientists and specialists are still arguing about what exactly humus is. I think for almost any reasonable yard purpose, mostly-finished compost is close enough, so I agree.

Anyway just noting that I understand and see that worm castings (or vermicompost) are sometimes called and sold as humus. I think that's mostly marketing, but nothing wrong with adding worm castings (don't know if I'd personally spend much money buying it, but to each their own).

There's also a wide variety of 'humus' or 'humic' liquids and the like sold out there, and the implication always seems to be that they have magical properties; I doubt any of them have much to offer that plain old compost doesn't have. But people will believe what they want to believe.

(to paraphrase the old joke, humus liquid works great to keep the tigers out of my soil - some don't believe it works, but I have absolutely zero tigers there).

It attracts dirt though. Just look at all the dirt that's there wherever you apply it.

"From what I can gather, scientists and specialists are still arguing about what exactly humus is."

I think that there is a lot of different definitions of humus - but not among scientists. Humus is the end product of organic decomposition. In other words when everything has been consumed and there is nothing left for bacteria and fungus to digest, you are left with humus. Humus is very stable and does not break down any further. Humus is essentially a wonderful environment for microbiology and roots to coexist. It does not in itself have nutrients, but it holds nutrients and water in the soil.

What you see sold as humus mostly isn't. It is composted material all right, but not really finished. There is usually more material there for fungus to break down over time and release as nutrients into the soil for plants. But that is good - you squeeze out a few more nutrients and in a year or two you are left with real humus which itself is a benefit to the soil.

Worm castings are also very beneficial to garden soil, but again, it is not humus. It is far from humus, really. It is partially composted (from the digestive system inside worms) vegetation. Again, great stuff, but it will continue to break down in the soil providing food for bacteria, roots, and fungus. But in the end after a few years it, too, will be humus. (As will we all, eventually.)

So from a strictly biological perspective, humus refers to the final inert state of the material that used to make up plants and animals once all available nutrients have been stripped away. But it is important to be aware of because it's presence in the soil makes plants and animals thrive. It is light, porous, and it holds on to nutrient molecules to make them available to roots and microorganisms.

"Brown matter has less nutrient than what "green" matter has."

Technically true - but that fact doesn't do your plants any good because it is not in a form that they can use. That's kind of where composting comes in, whether it is happening naturally on the forest floor or in a compost pile in your back yard. It is converting complex organic structures into their more basic building blocks that will benefit plants. And in that race, the high carbon leaves and branches have a straighter path to the plants than a pile of stinky grass clippings and kitchen waste.

Picture the forest - the vast majority of litter on the ground is high carbon material - leaves, wood, branches and twigs. There will only be the occasional "higher octane" fruit, green grass or leaves added to the debris. Yet, that is what feeds these ecosystems for tens of thousands of years. In other words, nature creates compost primarily out of "browns" with almost no "greens". Really, in order to have great compost all you need is wet brown material with enough air circulation. Probably the best garden supplement ever found is leaf mold - which is just shredded leaves left to compost on their own for two or three years.

So where do greens come in? Note that it takes multiple years for the browns to compost. What greens add is speed. If you up the nitrogen level you can breed heat loving bacteria that make very quick work of soft plant materials. Eventually they eat everything they can, and leave the tough woody structures for the fungus to consume. The fungus can't really be sped up - they still take their time. But the boost in speed from the nitrogen-loving bacteria can shave a year or more off the process.

So really the browns are a necessity and the greens are a luxury that just speed up the process.

And what about a mostly green compost pile? Well, it will break down - but in a different way. If the air collapses out of the pile, only the anaerobic bacteria will survive, producing their own smelly gas byproducts. It will then require more high level organisms (insect larvae, worms) to digest some of the material before lower level microorganisms can take over and break things down. In those processes most of the nitrogen will be used up and expelled into the air. This why the green pile begins as being high in nutrients, but by the time it is ready for plants most of that has been consumed and expelled along the way.

All of this is just to say - don't knock the brown woody stuff. They have been feeding our forests and are still the best source of organic nutrition available to your garden. (They just take a long time to get there.)

@richardbrennan, I agree with almost all of your conclusions (mainly that what is sold or referred to as 'humus' often is not, it's just partially composted stuff, and that browns are useful in soil and part of good compost / organic soil matter).

But two somewhat pedantic points: first, when I said even scientists don't fully agree on what humus is, I was referring to the actual chemical makeup and how it works (some claim its role is hormonal). (Even the existence/presence/importance of so-called humic acids etc is debated). That's mostly not critical for end-users - for almost all garden purposes, 'finished compost' or 'organic material that's (mostly) finished decomposing' is sufficient as a definition. (But it's clear that last stage of decomposition - mineralization - is not complete).

The second point: I don't think it's correct to say that humus is devoid of nutrients or that it's what remains when 'there is nothing for bacteria or fungus to consume' and that it's all been stripped away. It's stable, in that there is not much decomposing actually occurring, and the organic compounds in there are somewhat resistant to further decomposition, either because they're complex compounds (lignin and related carbo-polys for example or various byproducts of breakdown of other organic materials incl proteins and fats etc), or combined in structures with other soil components like clay, or physically aggregated (clumped) in ways that keep microbes and fungi at bay, or combinations of these and other factors. (Some of these components will get broken down especially if disturbed, exposed to air, ploughed and turned, etc). This includes 'nutrients' trapped in the humus that may, in certain circumstances, be available.

That said, partly depends how one defines nutrients and the role humus plays. It's mostly not a 'source' of nitrogen (which it seems to me is often what people are talking about) - nitrogen content and other macronutrients may be low or not directly available to plants; trace or micronutrients can still be present and important. Agree entirely with your point though that the more important role is enabling nutrient exchange, or holding nutrients to make them available.

Also very much agree that carbon - brown woody or pulpy stuff etc - is way underrated as soil/compost component. Plants don't (generally) directly make use of that stuff, so we don't tend to call it a nutrient - but all that stuff feeds and is consumed by fungi, microbes, bugs and worms and other wee beasties. And all of those soil denizens (or parts of the soil food web) do contain and recycle and move around and trade/exchange nutrients too (and die and become part of the humus as well).

Anyway, quite a digression. Still agree with your main points.