Re blowing stumps ... it was a tool farmers in my locale used to use a lot up until the 70s. I jumped though a couple hoops to get my permit in the 90s.
Rookie mistake on their part but I get a feeling the guy didn't do much of it ... I used to do this sort of thing a lot in the 90s. Lost my permits when Sydney Olympics were about to happen.
Four foot is on the shallow end of charge depth, and for a dead tree as such they'd have got away with a third of what they used easily ... in fact the same third packed down 7 foot would have sent a heavy green tree up with it's roots getting above tree height, and often with the whole tree landing top first into the ground a little bit clear of the hole. I did a lot for a neighbour who after a while got his own permit went the easy way with shallow ... sometimes not even 2 foot down, just used way more like a bucket's worth ... yes one could hear the boom quite some distance and also he was never one to bother with arm sized sticks fouling up the contractor's equipment. I would rather pick sticks off a couple square chain, and not 10 acres. I gathered though he didn't like the tamping exercise with a crowbar to ensure a tight plug.
Other BTW, yup the fresh dead animals scattered around is almost certainly fake, bird in a hollow branch nest possible, but stuck underneath the branch ... riiiight. It's the big old green blue gums and poplars are what the savvy bush going person or farmer is keeping an eye out for. Dead ones are just not so nice being near when it's windy or slashing or other ground work right beside them with a tractor that has an extended axle sticking out.
I had few acres of chain pulled country that left buried stumps, the big stumps were often a burning project, but dry country so not that much of an issue but I did try various things to help keep the stump burning underground.
I won't comment on levelling up around pine stumps as different ground, temps and rotting mechanisms here. Pine doesn't last at all here, if the rot doesn't get it in a year, the termites will. I almost always laugh at the tv hardware shows made down south using A grade termite food, treated pushed it to grade B but ... dry or wet rot are licking their lips.
When we cleared we aimed not to burn, bit longer and runs up to probably just shy of a fifth of a mile in some instances. I know other people around at the time think that's downright weird but after a while, even hardwood there's not much left after a decade or two, and with modern times we have herbicides so there no real need to mechanically control weeds around stacks.