The front corner of our place is a Beaver swamp. That is, it's actually a bog since there aren't any trees. This year I am going to see if the Beavers can help me improve some soil.
Since the Beaver bog is pretty shallow and the Beavers need deep enough water to stay under (without freezing) all winter, they build what we refer to as "Beaver Highways". Deep channels that they dig from place to place including an even deeper pond where they keep their Winter larder. They stay in the lodge, there are no "above water" exits all Winter, they need to have channels and ponds.
So why am I writing this in "Soil"?

When the Beavers dig their channels they take all the peat, mostly rotted leaves, water plant roots, Beaver crap, Turtle crap and other assorted "biomass" from the bottom of the bog and put it in hummocks. I just got back with a toboggan load of this stuff. It *looks* amazing. Like years and years worth of stuff that couldn't rot in the stagnant water and is now exposed to the air. It smells fertile and rich.
So I wish I had some litmus paper to measure the pH of my Beaver bog crud but I think that mixing it with a bit of poor soil is going to provide me with some excellent stuff... to start my tomatoes in. I'll work the rest of it into the place where I want to grow Spring lettuce. If that works I may even go out there and plant an Apple Tree or two.
Fun eh?