Would someone please come here and find me a piece of ground that absorbs the energy?! Sorry, but our ground is very hard and will not soak up any more energy than a stump would. In addition, if I am splitting wood, no matter if it is with axe, maul or hydraulics, it will be a cold day in that other place before I lift every piece of wood before I split it.
It is strange to me that many give the excuse of the ground soaking up energy but make no mention of the energy required to lift every log before splitting. In addition, I have watched some splitting on a block and most times when they split, one or another split will fall to the ground and then they are picking it back up to place it on the block. So which wastes more energy? Splitting on a block or letting the ground absorb a little energy?
I've also stated as have others that hitting the ground is not a concern of mine. In most cases, I know how much power it will take to split a log. If I am splitting some easy stuff, why on earth would I swing hard to push the axe or maul through the wood and into the ground. It is just like splitting with hydraulics; on the easy splitting stuff, you don't have to run that wedge all the way through the wood! Many times you barely touch the wood with the wedge and it will split (would be nice if all were this way). So, if I'm splitting, say, soft maple or white ash (we have lots), it is rare that I would put all my muscle into a swing.
One more thing about the splitting on the ground is that as someone else wisely stated, you have a longer stroke on your swing if your log is not placed on a block. That alone gives you much more splitting power.