Not really. The bag cuts off any air flow, which means that beneficial aerobic bacteria and fungi will be suffocated. And it usually doesn't have that sulfur smell of anaerobic bacteria, because then nobody would buy it. It's probably not completely sterile, as they have not bagged it direct from an autoclave, so there will be some microorganisms in it, but not a lot. Think of it as a big sack of chips that you are bringing to a party; as soon as you open the bag and offer it to the crowd, everyone will help themselves. When you spread the bag around to all your plants, the microorganisms that are present in your soil are going to see lots of food and no competition.
Some store bought compost actually does come in bags that allow air in. I know of two examples here in town. One uses burlap bags and the distributer has to agree to wet them down occasionally. Another uses plastic bags but there are some holes punched in the plastic (like what you would create with a hole-punch) for airflow. This actually came to my attention one time as I was slitting one of these bags down the front to open it up. I happened to slice right next to one of these holes - something I would have never noticed if it weren't for the fact that a small beetle was caught halfway in and halfway out of the hole. I cut him loose, but he was already dead (hard to tell with beetles sometimes!).
Most bagged stuff does occur as mostly lifeless, but I have found worm egg sacs in some national chain compost someone "gifted" me one time. That surprised me.
Subtropical desert (Köppen: BWh)
Elevation: 1090 ft Annual rainfall: 7"
posted 4 years ago
Thanks for the replies.
I had an idea that there would be either very little or no aerobic bacteria/microorganisms due to the lact of air.
Mo-om! You're embarassing me! Can you just read a tiny ad like a normal person?