Woah! Slow down on the composting.

2 years ago

There is a widespread misunderstanding that the final product of composting, “humus”, is stable.

In fact, humas continuously decomposes over a period of years. That is why more compost is added to the garden every year. That is why no-till practices, which reduce the amount of oxygen available in the soil reduces the breakdown of humus and other organic matter in the soil. That is why top soil is typically less that a foot deep in many parts of the country, even after many thousands of years of organic material naturally being added.

Only in areas with very cold soil, such as Alaska, very acid soils, such as peat bogs, or very low oxygen levels (swamps/bogs) does the slow decomposition of organic matter result in the deep buildup of humus and organic material. (Peat bogs can become several hundred feet deep over many thousands of years.)

I recommend that when practicable, composting be done by incorporating the raw organic materials into the soil or used as a mulch. The organic material will decompose slowly and release nutrients over a longer period of time, and the soil will maintain a higher percentage of organic material.

With respect to seed or disease issues, incorporating the organic material into the soil will resolve many insect issues. If the garden plant residue is diseased, the soil will already contain diseased residue from disease spores from dropped leaves, remaining roots etc. . Crop rotation is an effective defense against soil-borne disease.

Comments (3)

gardengal48 (PNW Z8/9)
2 years ago
Humus IS stable. It is just mistakenly believed to be created quickly. It is not - it takes years, many MANY years, for humus to be created and 'finished' compost contains very little ('finished' compost is actually very far from being finished :-))
beesneeds
2 years ago
I agree that humus is stable. Humus and compost are two different words for a reason, because they are two different things/stages. Humus is the stable stage of composting. Takes a long time.

Adding raw materials straight into the dirt works for some- they do it like trench or hole composting. For a lot of people composting it up a while first before adding it to the soil works better for them. It's not slowing down on composting, it's just composting in different ways.

Just some fun info- gridded global data set of soil, intact gegolith, and sedimentary deposits: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015MS000526

And a neat world map- it's in kilometers, but that is easy to convert if folks want to: https://webmap.ornl.gov/wcsdown/dataset.jsp?dg_id=1304_1
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John D Zn6a PIT Pa
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I don't know about the humus/compost issue. However the problem with compost is that there's never enough and then you want to start a new project and there's nothing at all in the compost pile.

If your property has nothing but raw clay this is an indication that nothing organic is being added to the soil and hasn't for many years. The portion of my property with a lawn has maybe +/- a half inch of sod. Under that is raw clay. When I add garden space from the lawn I add 3 inches of horse or mushroom manure, hopefully in the fall before I want to grow in it. I add the manure to the entire garden area, except that recently. i've been .ignoring the paths because of my age.

The soil is totally different after digging in manure the depth of spade and with additions the following years the soil starts to look more like loam than clay. The garden areas i've been working for 15 or so years is starting to like a nice rich loam.

Woah! Slow down on the composting.

Comments (3)

gardengal48 (PNW Z8/9)

beesneeds

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John D Zn6a PIT Pa

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