Humus is the residual of the organic matter in soil, what is left after the Soil Food Web has digested the organic material put into the soil. Coal is also humus as is charcoal. The same guy wrote this article a while back.

http://www.gardenmyths.com/what-is-humus/

So it sounds as if he is confused, like many others are, about what is humus.

kimmq is kimmsr

I'm certainly not qualified to comment on the scientific claim (as I understood it), that humic and fluvic acids and compounds are created by the testing process, i.e. that they can only be tested indirectly.

But whether true or not, it seems to me it's a distinction without a difference for most: humus is still the stable, residual portion of organic matter (after digestion by the soil food web). Which comes down to the same thing: organic matter is necessary and good (usual qualifications about everything within reason). And a thought experiment: if good soil with humus _when tested_ always gives the humic and fluvic compounds, do we care whether it was created by the test?

In a bit more detail, it's also been described (including in the article) as larger, more complex molecules, (sometimes?) aggregated with soil in ways that prevents its rapid decomposition into smaller molecules (mineralization).

In some soils with higher levels of 'humus', like black earth, it seems to contain (or have contained) higher fractions of cellulose and lignin, which are complex, non-standard shaped molecules and hence harder to break down completely (hence the carbon). And some binding with things like clay or other soil components. (Plus other plant remains like some proteins, fats, waxes, and resins). And all of this tends to have characteristics like ion exchange capacity, high levels of organic carbon, etc.

It may be true that purchasing 'humus' (as opposed to just compost) or products purporting to be humic is often just marketing, and as you put it, 'humus' is often just compost. (Who knows for sure, maybe those products have some other fabulous benefit, but no way for an average consumer to know, and very few standards....).

Anyway, overall, the article makes rather exceptional claims that don't seem to matter much. Good compost is still good, adding organic material to soil is good, and probably still worth being cautious about the (exceptional) claims of those trying to sell soil/compost products on the basis that they're 'humus' or 'humic' or whatever. Compost that has good microbial activity/characteristics will still better support the soil food web. In other words, not much has changed from reading these 'shocking' claims. (I don't mean to denigrate the science on this- I just mean that for most at this stage it doesn't likely change the approach to compost, and this article probably overstates).

From all the reading I've done about humus, the main take-away I got (apart from the 'compost is good' and related that most composters/gardeners know) is that compost with woody/pulpy (lignin/cellulose) may be really important (and more than I realised) in terms of creating more stable organic fraction of soil, resistant to further decomposition - like good humus. But I'm not sure that changes much for most or even me, apart from 'woody/pulpy wastes in soil and compost are good', and many composters/gardeners basically follow that anyway - they're prime components in many mulches and compost/soil mixes and get incorporated into soil that way.

Hummus is what you want with pita bread. And it's compostable too although there shouldn't be any left when you're done.

I believe that humus exists, but not in a bag at Home Depot.

I believe in the substance of humus hoped for and the evidence of microbiomes not seen.

+1 for each of the above posts!

Seeding is believing.

I don't think that the take home message is that people have been doing something wrong or that organic materials don't provide any benefit. It comes across (to me anyway) as "buyer beware" type information. In other words, before spending a bunch of cash on "SUPER HUMIC FULVIC ROOT BLASTING PLANT ACCELERATOR EXTREEEEME!", consider good old compost. It will likely provide more benefit for less money.

Kimmq: as far as the author's confusion is concerned, he actually mentioned his first article about humus in this most recent one. He was singing a different tune based on new information that became available in an issue of Nature that was published after the first article was written.

Is that the same squonnk from several years ago?

Is fulvic acid in humus considered rare compound that exists exclusively in humus but not other organic materials? If the answer is no then I would not worry about getting and putting humus in my garden.

As I have written here many times over the years spending money on something someone labels "humus" is probably a waste of your money. Add organic matter to the soil and humus will appear, eventually.

kimmq is kimmsr