Are folk just adding new bedding to used bedding without cleaning out the old?
It's a little different in that when cultivating a composting deep litter, it's more effective if a variety of materials are used so that there is no matting down of materials and the use of different particle sizes allows airflow in the mass.
It's more of a planned system rather than just letting things build up and cleaning it out in the spring...there's intention in the design and nature of the manure pack. Not just the use of one material as is traditionally used in what commercial systems refer to as deep litter...that's merely deep bedding~that's rather like a large diaper instead of the working DL, which is a living community of healthy microbes, insect and worm life.
Another thing of great importance is good ventilation, with good air coming in at the bottom and a way for it to escape at the top. None of that matters much in my pens as they are uncovered, for the most part, and only offer shelter around the hay and watering, so have adequate ventilation at all levels.
It's best if the DL has a soil floor but it can be done on cement if one is careful to add moisture when it's too dry and keep a bottom layer of compost at the level of the cement, and use it to inoculate the next start of building the DL.
Salatin does the traditional cattle barn setup in the winter months, confining his cattle to one area and allowing the manure pack to mount up, covering it each day with dry materials of a variety of types but his also has grains in the dry matter....he runs his manure spreader through his cattle barns to cover the daily manure and urine. The grains ferment inside the mass and the mass composts in place, providing heat for the cows in the winter months. In doing so, his cattle have to eat less to stay warm and are also not walking around in a soup of manure and urine like most cattle in a winter feed lot.
In early spring he brings pigs into that area and they root through the deep manure pack, searching for the fermented grains. All their rooting and moving of the material aerates it...he calls them his Pigaerators...and allows more composting of the materials. By the time the pigs are done in there, the whole mass is composted fully enough to be spread directly on the fields without any worry of too high nitrogen...it's bound with the carbon and is balanced and ready for use.
I don't have pigs but I have chickens and they do an excellent job of moving the top layers, but I have to provide air into the bottom levels with large, woody materials like sticks, corn stalks, sunflower stalks, wood bark, etc.
The DL in my coop has been in there for around 6 yrs now, never fully cleaned out. There is no smell, no flies, no messy feet...I clean out some each year to side dress the garden with, but I never fully remove all of it...I use it to inoculate the next year's layering of materials there. I don't turn the bottom levels at all and I just cover the feces under the roosts every other day or so, using the dry materials at the front of the coop to cover feces at the back of the coop....takes a few seconds to flip some dry stuff with the pitchfork and that's all the maintenance I do to it other than keep adding more materials as the old breaks down into rich soil.
I intentionally pipe rainwater into the bottom layers of the mass with a catchment system, but the top stays totally dry.
If it's working right, there should be no smell at all except for whatever was deposited freshly that night and has yet to be covered.
With sheep it could be more simple as the feces and urine are not in one package, like with chickens. Their urine should be wicked into the bottom layers of the pack and dyer feces remain at the top...if their feces are healthy, dry and formed pellets they shouldn't create too much moisture there. Using a variety of particle sizes will help the pellets to sift down into the pack and the chickens working the surface will implement that as well.
If one had no chickens and had a larger barn such as yours, they could run a small cultivator through the top layers to move the feces into the pack and thus eliminate the herd walking around on feces. Each layer of new materials would also facilitate that. With hay being the majority of the bedding, one could easily create movement and air spaces by covering the manure pack with something of different density of carbon and a different particle size~I'll be using leaves, wood chip, bark, etc.
Sounds like a lot of work but the actual work comes in small doses and is brief, ongoing maintenance whereas the traditional barn clean out is not...it's a tough, smelly job that no one likes to do. If we can let animals and microbial life do most of the work and we~and the sheep~provide the materials, it becomes much more simple.
I've only ever done it small scale but people like Salatin does it large scale and has figured out how to render perfectly composted material by spring that has no smell other than the smell of dirt. The added benefit of having no flies and no smell is a wonderful thing. I've been in sheep barns and they NEVER smell good, even after being shoveled out and hosed down...that ammonia smell lingers.
If I can find the right balance I'll give updates and detail mistakes made, things learned and the final results. Should take awhile to build up a working pack in those pens, as I need more material there than in my coop, but I'll be working on it all the while. It's soooooo worth it in my coop, so I imagine it will be worth it in the sheep pens as well.
When I listen to how folks are doing their yearly or biannual clean out, about how they are constantly having to fight odor and flies~and illnesses in the flocks or herds~it gives me some satisfaction to know I don't have those issues to worry about. I'd like to create the same system in my sheep barn so that I can have that same satisfaction of having a self cleaning system that's healthier for the animals.
