Question About Organic Matter in Dry Land Situation

I have a somewhat technical soil question I'm going to ask you guys.

Bear with me while I think out loud.

First, does syntropic farming work for dry land situations?

And in dry land situations, should organic matter ever be left on the surface?

The obvious answer seems to be yes, but I have seen posts about organic matter oxidizing straight into the air on this forum, and I've sort of witnessed something like that in real life.

My grandparents had a conventional farm in Western Kansas that I visited often as a kid. I still remember a giant pile of brush that never broke down over decades and slowly just bleached in the sun. It seemed like it probably never even helped the soil under it. Everything just seemed dead.

So I guess my question is, would it have worked as a Hugelculture if it had been well watered when it was established? Or would it have still dried out and sat there for ages, just with a little bit of dirt on top of it?

And the question that directly applies to my site is: will chopped and dropped plants have the same fate as that old brush pile? I do live farther east.  We do get higher rainfall. I think it can vary dramatically between 15 and 35 inches of rainfall a year.  It's usually on the lower end of that.

I don't want to pile a bunch of grass on the soil that will just sit there for all time. Or go straight back into the atmosphere. But at the same time mulch does seem like it makes the soil nicer underneath.  So even if it's going back into the atmosphere at least the plants around it are benefiting? I guess I'm just wondering if I'm only speeding up CO2 release or if chop and drop will do something to build soil. I just can't imagine that I will see the amazing soil buildup that syntropic farming promises.

Does syntropic farming and chop and drop come down to having the roots die in the soil and leaving their carbon behind? That would make some kind of sense to me.

I'm hoping that's the case because having to make everything into a Hugelculture sounds burdensome, to say the least.  

I lived out in Oakley for a good chunk.  My hugels did amazing without much additional watering.  I dug into them a couple years in and it was some of the best smells I have encountered.

I also did a lot of mulching with cut grass from the school fields, which looking back had a lot of chemical herbicides in them, but seemed to not bother my veggies much.  Those spots retained moisture well, and contributed to reduced watering.  I had to replace the grass mulch frequently as it was rapid in its decomposition.

I am now back in central Kansas, I have grown a lot in my methods but still use hugels, or at least wood in every one of my projects.  If nothing else, those brush piles contribute to the fauna around them.  Where there is fauna there is guano, which is a win for me!

I do heavily incorporate chop and drop comfrey into my routine now, and divide it yearly to get more.  My fruit trees are noticeably better than surround ones, and weed competition is down.  The soil does get better down below the surface as worms and critters eat and burrow, and the top layer is constantly improving through the breakdown alone. From my understanding chop and drop is mostly beneficial because the deep taproots draw the nutrients from those depths to its foliage, which then decomposition does its thing to make it bioavailable to the shallower rooter plants.  Root decomposition is more important to me in my nitrogen fixing plants, as I want that fixed nitrogen to reach the rest of my plants.

I would suggest that dry situations, the more organic matter the better.

Though it might be hard to get the green/brown ratios.

A load of wood chips would put folks ahead of the game, though.  Just leave it in big pile to do its thing.

The oxidation thing is probably more of an issue with fine materials like bare compost sitting exposed in windy spots. A thicker mulch layer tends to insulate itself. Matthew's hugel results in Oakley back that up, if it was oxidizing away quickly he wouldn't have had the moisture retention he did.