Placing leaves in bottom of hole

I am wondering if putting some dead leaves (that time of year) into the bottom of a hole before planting a tree would be of any benefit and add some biology to the clay.
I have thick clay just a few inches down and want to do something to jump start the soil for when I plant the fruit trees (seedlings) in the spring.  Pawpaw and American Persimmon.
Since I have a concern with large rocks being just below the surface I will use a small backhoe to dig holes a couple feet deep and then fill the holes back in.
I have ordered some expanded shale and was thinking of using some of the many oak leaves that get placed on the streets here.  
Would vermiculite or something else help here?
Looking at a $100 hole for a $10 tree.

Leaves tend to compress and mat and go anaerobic from my experience - my first choice would be punky wood in the bottom. My second choice, particularly with clay soil, is to make some biochar, inoculate it with compost tea and mix that in with the leaves. I've not had enough time for my experiment mixing biochar with no inoculation with duck shit and leaves. But the ducks are pooping on it as I type!

That said, if you mix the leaves with stuff that worms like, that could help a lot.

I've also read that if you put too much good stuff in a tree planting hole, the tree won't work at spreading its roots. To avoid that problem with an apple tree baby I planted last year, I dug a compost pit about 3 feet away. Ideally I'd have done three holes ~120 degrees apart, but the area didn't allow it.

I hear you about the rocks - I grow rocks *really* well. Where one tree was less than happy, I dug out a trench past its drip-line on the up-slope side and put lighter dirt and comfrey. The tree seems happier now, although it didn't fruit well - I think it was lack of pollinators plus squirrel pressure. A second tree where the fruit was quite small, I dug a longer but shallower up slope ditch where the path was and split large slightly rotten rounds of wood and set them under a bit of soil with the flat sides up to preserve the path. That tree did quite well this year until the deer and squirrels showed up.

I don't think there's any perfect answer - it depends what you've got available. If leaves are plentiful and you can mix them so they aren't just matted together, they will decompose. Just remember that as they decompose, the tree may sink.

Thanks Jay.  I was thinking a small handful of leaves just to get some biology going in the clay.  I have some EM also.

If you put the leaves all in one spot, I think it would probably do more good than bad.  If you did a thin layer, they could form a pond liner effect and hold too much water at the bottom of the root ball for a year or two.

After a lot of feedback I think I will just put down some composted Horse manure and a lot of wood chips.  My soil analysis (logan labs) indicated I am very low in nitrogen. After planting the trees I hope to have a lot of compost ready to place around each seedling.
This will make the task a lot easier in the long run. Digging a lot of deep holes would take time and effort that may be better spent putting down the micro-nutrients called out in the soil test.

I've been dumping leaves in what I guess you could call a hole, its a depression about 10'x10' that's a few feet deep, and I layered in a bunch of branches a few years ago and now there are a bunch of bulbs spreading in there and blackberry brambles. and this is an area that the soil is heavy red clay. as the leaves and twigs break down it creates thick layers of dark colored soil that is very fertile

That was what I was thinking but I am just trying to rush things.  Maybe finish that compost injector that Dr. Redhawk described.  I have huge piles of woodchips now so I can put down 12 inches.

I have had poor results burying leaves and excellent results layering them on top of the ground.
Decomposition seems to happen from the soil layer on upward.
In a hole,  especially in clay,  not much seems to happen.
It reminds me of coating straw with clay slip.

For your trees,  maybe dig  a wide hole rather than deep?
Also,  a tube inserted into the hole at planting can allow deep watering,  which conserves water and encourages deeper roots.

What kind of nitrogen fixers are you planting?

I have goumi going now. Red Gem and Sweet Scarlet.  I think planting between the trees will work and provide snacks while in the orchard.
I have a high water table that is on top of a rock shelf.  So dry clay is not a problem.  I have found a couple of artesian wells (or high water table) on my property so mounding is something to consider here.

I have posted this before, but I think it is worth repeating.  I don't have all the answers by any means, but I have planted literally thousands of trees.  When I started planting trees years ago, I believed the old saying about a $100 hole for a $5 tree.  Personal experience has shown me differently.  Now I never amend planting holes.  I plant in native soil only, and pile good things on the soil surface.  I have had much better luck.  Making a fertile hole in a sea of bad soil creates a situation where the roots grow really well, hit the "walls", and either start going in circles around the hole, or just give up.  Either way, the tree gets stunted.  It's easy to test for yourself, although it takes a while.  Plant two trees of the same type.  With one, make a very fertile hole.  Make it as big as you like.  Plant another tree nearby in native soil.  Use the same amount and type of amendments but put them in a ring on top of the soil.  I think you will find it eye-opening.  If you have wood chips available, the are the absolute best thing to pile around the tree in my own humble experience.  4 inches is good, 8 is better.

Putting wood in the hole was mentioned.  I personally wouldn't do it because the wood is going to rot at some point, and your tree will be growing in a hole.

I have a lot of water as well but only one tree in a "mound".
It's about 20' tall,  and seems very stable, so I guess it has rooted OK.
It's a pear tree in a raised bed,  two cinder blocks high.
The blocks are on their sides,  so it's kind of an air pruning situation.
Adding amendments on top of that, this tree gave me a huge harvest this year.

These results have made me wonder about doing more of this.
Digging tree holes is a non-trivial task at my grow yard.
The whole plot is full of stones.
Maybe I can get by digging till I hit rock,  setting the tree in the hole and mounding up from there with wood chips.

William Bronson wrote:
The whole plot is full of stones.
Maybe I can get by digging till I hit rock,  setting the tree in the hole and mounding up from there with wood chips.

I do something similar in rocky, bad areas.  I dig down as far as I can comfortably, set the tree, and if it is high, I mound with native soil from nearby.  Once the tree is planted, then I mound the wood chips on.

I will be doing seedlings so a hole will likely be made by a metal spike and hammer.  My logan Labs soil analysis will tell me what to put down on top of the soil and then horse manure (low nitrogen) and lots and lots of woodchips.  The tree service guys like me.  

like Dennis is saying I would not expect leaves to turn to compost any time soon if buried in bottom of hole with a potted tree on top. make compost first then put it in a hole under potted tree, might even include some biochar to ensure long term fertilization.
when I first moved to this place I stopped along the way at a highly respected nursery at ty ty Georgia and got some fruit trees, dug the holes, amended the soil and only about 1/2 of em survived. the hundreds of bare root nut trees I planted I just opened up the soil and stuck them in and closed it back up and probably about 95% survived. just my experience

I have thrown fresh oak leaves over the garden fence from late fall and over the winter and then in the spring dug them in. I have never found the leaves again. It's my opinion that if you mix the leaves into the hole that they won't cause any problems and will be a big improvement to the soil. Myself; if I had manure I'd mix in both that and the leafs. The one problem I did have was that it's harder to get the spade in the ground when pushing it thru a layer of oak leafs.

I totally agree with Trace.  On a clay soil digging a big hole and filling it up with all kinds of improved soil and loose fluffy amendments is a recipe for disaster.  When it rains heavy water will fill all the loose airspace in there and only very slowly seep away into the surrounding packed clay.  Imagine a bucket sunk into the ground with the tree in it.  A day or two and it drowns!  This has happened to me on multiple sites multiple times.  On a sandy or loamy soil it isn't an issue....dig, improve, bury what you will and the tree will thrive.  But not on clay!  On clay now I plant directly into unimproved soil, only dug out enough to accomodate the roots.  Most fruit trees actually get planted on mounds raised above grade....especially if water hangs around in puddles for a while after a good rain.   The portion of the mound above grade can consist of improved soil, but it's even better laid on top as mulch.  If you really want to bury something nasty but valuable for the trees, like humanure or slaughter waste, put it into a separate hole off to the side...the roots will grow over to it and access it eventually.