I'm not sure what you read that made you so pesimistic. I will tell you that I certainly felt that way to start with. I live in the NC piedmont which stands for a deep vein of red heavy clay soil. White clay is even worse as it indicates that air can't get into the small particles and rust the iron to red. However it is plenty hard and slimy clay like when wet. We have the largest hand thrown pottery community here. Thirty miles south, the soil turns to sand and the interface is the brick capital of the country! I doesn't appear that anything except grass will grow in this soil. However, if ammended heavily with bulk, it does wonderfully as it holds water and nutrients extremely well. We are in the country. I found a cattleman who has cow manure/bedding piled up and mixed after being mucked out of the barns. I bought a dump truck load (I actually bought two and moved it multiple places later) and had a third to a half of it dumped in my ~25' x 35' garden and tilled it in. That could have been between 6 to 10 cu yds of black composted manure. That changed the texture of the soil and it is still there after 6+ years. Gas was much cheaper then and it cost me $60 for delivery and $50 for the manure. Would be much more now for delivery.

My soil is brick hard, heavy red clay with a thick Bermuda grass lawn. so I wanted to plant in raised beds rather than fighting this soil and invasive grass. I covered the existing sod with 4 layers of cardboard boxes to smother the grass, and put everything on top of that. In the thread "Reheat old pile in new composter??", I posted a comment "Cold vs Hot Compost" where I explained how I simply piled 6 feet of leaves and grass clippings inside my raised beds last fall and left them all winter. By spring I had a foot of rich leaf mold in the 3 raised beds where I planted herbs, tomatoes, and peppers. Last week I was removing a few of the determinate tomato vines that were past their prime and replacing them with some suckers I had removed earlier and rooted in pots. The roots of the old plants I was removing were anchored very well into the clay soil beneath the bed. The earthworms, soil microbes, and plant roots together have already begun to improve the tilth of the hard clay beneath the bed. There was no sign of the grass sod or cardboard boxes; the worms had eaten them all up. Last fall I had originally planned to double dig the area beneath the raised beds, until I found that I could not dig a hole more than a few inches deep. After only 9 months since I piled up the leaves, using only a hand trowel, I was now able to easily dig 6 inches into the original soil beneath the beds. It would have taken a jackhammer to have dug 6 inch last fall. This fall I'm planning to mix in more leaves to compensate for organic matter that has decayed this summer. As soon as my neighbors rake their leaves and put them by the road, I'm planning to drag them home with me to start a 4th bed for strawberries next spring. While double digging beds used to be considered the "gold standard" by which to get great results, new research is increasingly going the other way. I was reading a report on the Rodale Institute's website recently about mycorrhizal fungi and its benefits to crops. To maximize mycorrhizal colonization, their research is showing that you should plant cover crops which you mow down rather than turn under. By disturbing the soil as little as possible and keeping cover crops growing whenever fields are not in production, the soil supports development of more beneficial microbes that maintain the tilth of the soil better than plowing does. I've got a long discussion going about mycorrhizal fungi in the container forum. While soils often contain enough of the fungi so that inoculants are not needed, there has been some debate of whether plants in containers could benefit from inoculation with mycorrhizal fungi. Some said that the high temps in containers would destroy the fungi, but new research suggests the fungi survive the high temps of soil in containers during summer and are a great help to plants in containers during hot weather. Once you establish a healthy soil climate in the raised beds, recent research suggests that the microbes and plants will take over and do everything that is needed to maintain improve the soil beneath the bed as well.

Thanks for the useful information. The crabapple tree belongs to the city and was planted last week (as our house is new). We already made the apple tree as far away from the white pine as possible. Since crabapple is a medium-small tree (15-20 feet tall), we expect the white pine to outgrow the apple and eventually outlive it. Other than the apple tree, the white pine's root has about 20-30 feet of sod to grow under in all other directions. There are quite a few healthy white pines growing in the neighborhood. There is a big, wild one right beside the river, which has nothing but heavy clay. Plus our the builder already laid 4" of top soil beneath the sod. From the information I gathered, white pine can tolerate clay as long as it is well-drained. We made sure the entire root ball is on or above the grade, not below. By the time the roots extend below the grade, they are already growing in the same topsoil / clay as the surroundings. There is also a slight grading that helps drainage. We planted the pine about a month and half ago, and so far it has shown some new growth of roots and needles on top. Earlier we also planted a red maple 'October glory' in a "raised donut" - not raised as high as the pine, with a shallow water basin in the middle. The maple seems to have recovered from the transplant stress as most of its foliage has returned to the same green as it was in the nursery.

Many kinds of maples are adapted to heavy soils and are planted in them by the thousands, as along streets for instance. It is the Japanese maple that is unusually touchy about drainage. If this planting site is big enough your best bet would be to excavate the clay soil and replace with lighter soil. If it is a narrow strip and the area becomes quite wet even that may not work, water coming in from the sides. Planting a tree or shrub over loosened soil is not a good idea because as the soils settles after planting the new specimen may sink to a level below the desired depth. Digging organic matter into a heavy soil will not have a lasting effect on the texture of the soil as the organic matter will gradually decompose and disappear. Even when non-decomposing amendments such as sand are used to alter the texture of backfill if the planting area is a small one there will still be the problem of how water moves into and out of the planting area being affected. Small areas of one soil texture surrounded by a much larger area of another are often a setup for problems. A large bed of soil amended with sand or similar material will also pose the problem of what to do when the dug over area rises up like a loaf of bread after the amendments are dug in - unless a soil already has a fairly high sand content a huge amount must be used to alter the texture of the finished bed significantly. If you can't excavate and replace a wide area of soil there or put a layer of more suitable soil over the top then it many just be that you can't safely plant Japanese maples in that particular spot. However, since you are in a fairly mild climate zone possibly it would be acceptable to plant them in suitably large tubs and place these on top of crushed rock or other covering in the same location.