If anybody wants to debate whether peat moss is renewable, please do that in the Official Peat Moss Renewability Thread.

Peat moss doesn't break down much more than it has already, so it doesn't add a lot in terms of nutrients.

It will loosen soil and allow air to get in. It will also help sandy soil retain moisture and help moisture get into clay soil. But one drawback is that if it dries out, it can repel water. If it's mixed into the soil thoroughly enough, I think this is less of an issue.

The best soil is a mixture of 45 percent mineral (that is the sand, silt, and clay particles), about 5 percent organic matter, about 45 percent air, and about 45 percent moisture and what you want to do is make a soil that will retain about that much moisture and air. The best way to do that is to add organic matter to your mineral soil, whether sand, silt, or clay, and the best OM to add is anything you can get at low cost or free.
Peat moss has no nutrients and is a non renewable resource, and is a very expensive soil amendment that adds nothing of value to your soil. Any other form of organic matter is better and tree leaves, where available, are a very good renewable source of organic matter for the soil. There is a planting bed where several years ago I mixed in a bale (3.8 cubic feet) of peat moss into a 4 foot by 4 foot planting bed and I can still find evidence of that peat moss in that bed. If you spend money on peat moss you will alos need to spend money on some nutrients to add to that soil while if you add compost, or leaf mold, that more then likely will not be necessary.

"Sphagnum moss" usually refers to the plant material that is harvested live and then dried. "Sphagnum peat moss" is harvested long dead. "Peat" is older material on its way to becoming coal.

Sphagnum moss is great for starting seeds and rooting cuttings because it has natural antibiotics and fungicides that protect the seeds/cuttings from disease. I read somewhere that it was once used as surgical dressing. It breaks down quickly, maybe, a month in soil but I am unsure. I am sure that peat moss visibly disappears in my soil in two years.

Thanks for the responses. Your comments and links got me to deeply dive into the use of my Sphagnum mixture. I will mix a small percentage (say 25%) into my soil and add organic matter. I have alot of oak leaves and the pollen strings from the oaks. But Oak is supposed to be acid. But Sphagnum has a PH of 3.4-4.2. So that also is acid. One source said, "The water in Sphagnum wetlands can reach a pH as low as 3 Â about the same as the pH of orange or grapefruit juice."
If I had it to do over I would not have purchased the Sphagum. I will use it but at a low percent and well blended with the sandy soil.
Thanks,
Bob