I haven’t done the trashbag method, but I have learned how to speed up an existing compost pile.
The compost process is helped by warmth, moisture, air and pressure. This encourages the fungi and microorganisms to go to work.
First, I walk on top of mine to create a flat surface. If the pile is dry, I"ll water it thoroughly. Then I use a muck rake to shovel up the outer edges and pile it on top - so I’m making the pile taller and denser which creates pressure, trapping moisture and creates warmth.
Hopefully, the outer edges I placed on top are nice and moist and black looking, with lots of fungus/mold. If not, I dig around the pile or dig somewhere else for some nice black earth and put a layer of that on top.
Compost generally starts from the middle/bottom of the pile and works its way out because thats the warmest, moistest, most dense spot. But I’ve found if I put a good layer of partially composted material on the top, I can accelerate the process from the top down too.
Then I cover the pile in old hay. Peed on hay is best if you have it, the urine helps increase nitrogen and the hay breaks down rapidly, feeding the compost layer that was put on top and helping it reach down into the pile faster.
Finally, I put a tarp over the top of the pile and secure it around with rocks or tree limbs to keep from blowing away. This locks it all in, like the trashbag method.
What it doesn’t do however is allow for air, which is a key component. So every 3 weeks, I’ll pull off the tarp, walk on top of the pile, turn the edges into the center and recover. This is enough aeration I’ve found on my modestly sized piles.
My compost piles range in size from a bedded 13h pony to a bedded 16h draft. The initial prep I described takes me about 30 minutes, and maintenance every 3 weeks about 30 minutes each time.
If conditions are dry, be sure to water the pile, it will not break down if its not moist.
If you can help it, avoid wood products like shaving of any kind, tree branches and leaves. They slow the composting process.
Hope this is successful for you!