How to use dry sunflower stalks in my soil?

I need to build my soil. I have a lot of old dry sunflower stalks.

What is the best way to use the stalks?

Should I run them over with a lawn mower to mulch? This turns them into powder.

Should chop them into small pieces and mix them with the soil? If so, how long? A foot long? An inch long?

What about the dried sunflower heads? Okay to put those in the soil?

Why not make a hugelkultur bed with them?

Yes, put dried sunflower heads in the soil as you might get more pretty sunflowers.

Sunflower stalks will add carbon to your soil. Many areas of North American have lost a lot of carbon from their soil due to too much tillage. So I try not to dig my soil too much, but sometimes I need to so that good stuff goes where I want it. It's a balance.

Walter Byrd wrote:Should I run them over with a lawn mower to mulch? This turns them into powder.

I would worry you would loose a lot to it blowing away. Powdering a little of it to add to potting soil would be different.

Should chop them into small pieces and mix them with the soil? If so, how long? A foot long? An inch long?

I would try a foot give or take. I would dig as narrow a trench as possible, lay the stalk down in it, then cover it back over sort of like if you were planting a potato.

Have you visited our biochar forum? ( https://permies.com/f/190/biochar ) If you can get a lot of sunflower stalks, making biochar, activating it with compost tea + pee, and mixing it into your soil could really  help with soil building.

Great resource you have there!
I put my most substantial biomass in the base of my beds, and top my beds with the stuff that breaks down easily.

If you have established beds you want to amend, I would use the mower to pulverize the stalks, and top your beds with that material.
I would add some nitrogen to that, alfalfa meal, urine, grass or such.
If you can chip the stalks to chunks, I would use that on top of the pulverized stuff.

FYI, The sunflower stover should be a good soil builder but is high in carbon. The carbon to nitrogen ratio is important in understanding how quickly or not residues break down.

AI Overview
The Carbon-to-Nitrogen Ratio: A Key Factor in Plant Health ...
The carbon-to-nitrogen (C:N) ratio of sunflower stover typically falls in the range of 30:1 to 60:1, often cited around 40:1 to 50:1 depending on the maturity of the plant. This high ratio indicates it is a "brown" material that decomposes slowly and may cause temporary nitrogen immobilization (microbes consuming soil nitrogen to break down the carbon).

https://eupdate.agronomy.ksu.edu/article/crop-residue-decomposition-and-nutrient-release-rates-442#:~:text=What%20determines%20how%20and%20when,N%20will%20be%20tied%20up.

I knock the stalks over and then step on them to break them up a bit and just use that as mulch.

I just stomp mine flat and leave them as mulch, they break down over a season or two. The heads I chuck straight on the beds, sometimes get a few volunteer sunflowers which is never a bad thing.