I've seen something like this before. Writing about moisture retention, only, I can say that hugelkulture beds would be more drought-proof. I've constructed many compost piles outside of a bin. Left unturned, they always dry out. Many of these compost piles were contained with hog wire. However, if the inner compost bin were shielded from Oklahoma wind and also have a cover. It might work just fine for moisture retention. I like the nutrient aspect of this idea.

This sounds similar to Japanese Tomato Rings, which I have used here several times, especially in our first 4-6 years here before the soil was as well-improved as it is now. The plants grew great and the yields were incredible, but the Japanese Tomato Rings took up more space in my garden than rows of tomatoes take up. However, I did cage my tomato plants to support them, even though they were around the compost-filled Japanese Tomato Ring and I'm not sorry I caged them. Those plants easily hit 8' in height and 4' in width and string wouldn't have held them up. The tomato cages barely held them up.

I also stood up a black plastic perforated drainage pipe in the middle of each ring and packed the compost in around it, so the pipe stood up on its own, or maybe I staked it...I don't remember now. Most of those years were drought years, and it was easy to water both the compost pile and the plants by inserting a water hose into the top of the black perforated drainage pipe and filling it with water that drained out throught the perforations in the pipe.

How To Build A Japanese Tomato Ring

That is very similar to the raised beds I made with old pallets. They were four feet high and completely full of compost. They grew anything I put in them.

I haven't tried the rings myself but I just thought it would work where someone was raising only a few tomatoes. It would probably be better where tomatoes were planted in an open type garden space instead of raised bed. The idea was that you could pour water in on the stuff in the ring and let moisture seep down into the soil for the tomato's during dry weather not to make compost. After the season is over you can pull up the ring and spread out the composted material. Hugelkulture is a good idea in some places where you are not bothered by rats, gophers, Pygmy Rattler's, Copperhead's, Water Moccasins and the occasional Timber Rattler but it wouldn't work in my area. A few years a go a woman and a young boy were bitten by Timber Rattler's just a couple of miles from where I live. Luckily I haven't had to deal with Timber Rattler's here but I have plenty of all the other kind to have to deal with.

Timber Rattlers are my garden nemesis, my constant nightmare, and the reason my garden gets weedier and weedier as the season progresses. Once I am seeing timber rattlers too often, I stop weeding and it isn't like it even is an option. I have to stop weeding at that point because to continue to weed is too dangerous. Usually, if I have had a close encounter with a timber rattler (or any rattlesnake or any other venomous snake) in my garden, even if we have shot and killed the snake and removed it, I know others may be there so I steer clear of the garden for a day or two until my nerves settle back down. The snakes also are why my entire garden isn't built on hugelkultur beds. I used them in Texas in the 1980s and 1990s and loved them (though I didn't know there even was a name for what I was doing back them), but when I have tried to build them here, they have become snake magnets in every single case.

I did love my Japanese tomato rings, which I also first used in Texas (though my main motivation was to hide the compost pile so people couldn't see it from the pool), and they served their purpose here, but I did find it more efficient to grow in rows.

For reasons I cannot explain, the timber rattlers come out of my neighbor's pasture (he has a large woodland within the pasture) at the same exact spot every time (it may be a deer trail or rabbit trail), slither across about 12' of ground after they enter our property, then come across the driveway, and they head right for my garden gate every single time. I have an uncommonly high number of timber rattler encounters right at the garden gate, even though plenty of other snakes just slither through the woven wire fencing at various places and enter the garden that way. I don't know why the timber rattlers prefer to try to use the gate. To help cut back on this issue, when we rebuilt the entry arbor a couple of years ago, we put a wood 'threshold' across the bottom of the entry gate area so that when the gate is closed, it is up snug against the threshold and that seems to help keep the snakes out. Still, I wish I had a quarter for every time I've almost stepped on a timber rattler on my way to the garden gate. They are the one snake that the neighbors warned me about repeatedly when we moved here, telling me over and over and over again that a bite from one of them could kill me whereas a bite from a copperhead would only hurt and make my life hell for a few weeks. I bet I see 10 timber rattlers for every copperhead, though copperheads are more common earlier in the season and timber rattlers from July onward.

I don't remember having snake issues with the tomato rings themselves, but maybe I just wasn't paying attention. The longer we have lived here and the more snake encounters I have had, the more careful and cautious I have become. I probably wasn't careful enough or cautious enough in our earliest years here and was lucky that I didn't get bitten.