Bark vs bark fines, chips, etc

[zeroma]

Reading some of the threads about mixing your own mix for containers I see bark fines and bark chips, bark compost mentioned along with other similar bark things.

What texture would these items be? When mixed with composted manue (40# bags)
and other items.

Is the purpose for texture/oxygen/light weight?

[Redbaron]

The main thing, at least for me, is to have a balance between the high nitrogen mulches (green) and the low nitrogen mulches (brown).

Now I said green and brown but it isn't really the color always, just as a rule of thumb ie Grass hay manure and things like that VS Leaves straw wood chips bark etc

In reality to get technical it is about the carbon to nitrogen ratio. High carbon low nitrogen decomposes slowly and low carbon high nitrogen decomposes quickly. They also generally have different specialized microbiology.

So by making a good blend you have nutrients early from the faster decaying materials and nutrients later from the slower decaying materials. AND a higher biodiversity in the soil which helps prevent disease.

Whats left after decomposition, no matter which source, is highly stabilized carbon called humus. That carbon by itself has no nutrients for the plants, but carbon has the ability to absorb and lock nutrients when water passes through it. That's why we use activated carbon or activated charcoal filters for aquariums or for our drinking water! With healthy biology in the soil, plants have the ability to use some of those locked nutrients when needed, but can also leave them alone and locked up when they don't need them.

This gives high carbon soils "loams" the ability to withstand bigger fluctuations of moisture, Ph, nutrients, salts, heavy metals, minerals etc... and still grow good crops. Other soils can be just as fertile or more, but they don't withstand fluctuations as well.

You are not going to get true "humus" right away. Whether it decomposes fast or slow, humus takes time to produce. About the fastest amendment you can add to get the "humus" effect is charcoal (biochar)

Now personally I don't grow in containers much at all. Only a few small potted flowers for decoration. So I am not too sure how this is all managed and blended in a container. But that's how it works outside in the soil.