Lots of good replies here. In a nutshell: Sand is weathered rock. Tiny little pieces of rock, broken down by wind and rain and erosion. Silt is weathered sand. These are primary minerals, broken down rock. Clay is different. Clay is a secondary mineral, created from the chemicals given off by sand and silt as they break down into smaller particles through exposure to acids like acid rain or organic acids. Clay particles are tiny plates that fit together very tightly and are attracted to each other by electrostatic charges. Time is the main difference. It takes longer for clay to form than either of the others. Sand, silt and clay are moved around by wind, water and ice. Vermont is rocky because it was scraped bare by glaciers and has not had time yet to develop new soil. Same thing where I am, in the Puget Sound area which was carved out by glaciers. Our soil is what the glaciers dumped as they melted off after carving out Puget Sound and the Strait of Georgia and Hood Canal. It's like gardening in aquarium gravel. Rocks, gravel and sand. No organic matter. I wish I had clay. The river valleys have really nice loamy soil, because they get what's washing down off the mountains - organic matter from the forests, clay from weathering, volcanic ash off Mt Rainier and Mt St Helens etc, and not least, thousands of dead salmon every fall. Migrating salmon returning from the oceans, going up the rivers, spawning and dying and washing up on the banks. The best fertilizer on earth. Prairie soils develop when thick grasses trap wind blown silt and clay. A nice loamy mix of organic matter and soil. Clay soil is what it is. Best to learn to work with it, not against it. You can't change it, only replace it in small areas. Organic matter disappears because the soil microbes eat it. The sand disappears because it gets lost in the clay matrix and sets like concrete. Clay soil is much more fertile than what I have. Clay particles have a very large surface area to volume ratio, so nutrients have lots of surface area to stick to, and stick they do because clay particles are electrostatically charged. In my gravelly soil nutrients wash right through, there's no clay or organic matter for them to stick to. Sand and gravel have no electrostatic charges. All you need to do is add compost and mulch every year. If you have a good worm population they'll work it in. When I had clay I did dig in organic matter whenever planting something not native to the area, and then mulched every year. But if you add a lot of amendments to a hole in clay, you're just creating a clay pot and the plant can drown because water won't drain from the amended soil into the clay. Just add a little bit in a big hole.

Scarlet Oaks do nicely in slightly acidic clay soil. You found out when digging the hole, the fact that clay not only holds on to water very well, it also quickly releases the moisture it contains into voids in the soil. You dug a hole and not only the rain filled it with water, but all the water in the clay soil around the hole kept filling the hole until the water pressure in the hole became close to the same as the water pressure in the soil. Then as evaporation occurs the water which turns into vapor and rises away is replaced with more moisture from the soil, until there is not enough water in the clay soil to replace that which has evaporated. At that point the clay will begin to absorb enough of the water in the hole to once again bring the pressure of the water in the soil to be equal with the water pressure in the hole. Only once that process begins to happen will you be able to notice the water level in the hole beginning to lower. This is the very reason why it is a bad idea to dig a hole in clay, plant the tree, and backfill with a different kind of soil. In that case the backfill soil will remain full of water, not only from rain and your watering but also from being kept filled with water that the virgin clay soil is holding. The backfill soil needs to be the same as the virgin soil which came out of the hole. By doing so the pressures remain more even and the there is much less of a void in to soil situation presented. This is also why it is bad to plant a root ball that is full of potting soil directly into clay. Instead as much as possible of the potting soil need to be washed away from the rootball mass and refilled with the virgin clay soil as what is found around the planting hole. That is why it is best to plant trees when they are in their dormant stage. If for any reason you want to amend the clay soil where your tree is to be planted, there must be amendment fairly evenly mixed into the virgin soil for a very wide spreading area. The more clay ratio in the virgin soil the farther spreading you planting bed needs to be that you amend. The amended area needs to be at least 6 times, if not more the width of the tree's rootball. Also, plant the tree with the rootflare about 3 to 4 inches above the soil level. After the tree is securely planted, and staked if needed, only then back fill the exposed 3-4 inches of raised rootball with a good quality and fairly finely shredded cedar mulch. Just make certain you do not pile any mulch above the topmost part of the rootflare. The trunk should not appear to look more like a post sticking out of the ground. Instead you should be able to just see where the topmost part of the root flare is growing out of the trunk. Finally never pile any mulch all the way against the trunk, make certain to leave all mulch at least 4 or more inches away from the base of the tree's trunk.

Here is a follow-up development: While I suspected the tree suffered from chlorosis from the alkaline heavy clay, I bought a can of iron-chelate and experimented it on one of the branches. I dissolve a few grams of iron-chelate powder into about 2L of water. Then I dipped all leaves in the "experiment branch" in this diluted iron-chelate solution. I then dumped the iron solution right onto the root ball. After 3 days of the treatment, I noticed that the dipped leaves appeared much greener than the rest of the tree, which hasn't improved (or got worse). So I still suspect cholorsis in play with the red maple tree. I am going to dip more leaves to see if there is any good improvement. By the way - against all wise advises we still decided to replant the tree in order to: (1) Raise the tree bed to improve drainage (2) Cut the circling roots (3) Most importantly, remove the sod that I, due to lack of experience, burried at the bottom of the planting hole. At the time of exvacation, the root ball was swimming in a large pit due to poor drainage (not visible from the surface). The smell was awful (guess this is what CSI calls "decomp"). We removed all of the decomp mud, washed the tree's roots, and cut off the roots that have been affected by the rot. We also cut off the encircling roots. We then widened the planting hole from 2.5' to 3.5', filled it with fresh black earth & clay (30-70 mix). We elevated the root ball to be about ~6" above the ground surface. We compacted the mound to make sure there wasn't large air pockets. Then we covered it with ~4" of red cedar mulch, leaving about 6" of space around the trunk. It looks like a large red donut circling the tree. Hopefully the tree will recover from the surgery.

They do need a bit of room to grow. I guess mine are about a foot apart in a row. Two rows about 18 feet long and about 3 feet apart - and I think I've planted them closer than recommended. When the spears are mature they can be 5 to 6 feet long and drape/spread many feet in any direction. So this plant can take up some room in the garden. Leaves, grass clippings and poop all qualify as organic matter but I would let the manure rot for at least a season before I let it touch any part of a plant. Some plants are sensitive to blasts of high nutrition, it can burn leaves, stems or roots. You would want to bury the organic matter deep in the bed (1 to 2 feet down) before you plant the roots and then top dress the rows every year after that. I would wait until after harvest season to put any new manure on the crop (to avoid contamination of your food). I don't feed mine on any sort of regular schedule. You can find good roots of named varieties at most farm supply stores or large garden centers. There is no need to mix up the varieties. I believe the roots in stores are sold in 15 root bundles. It takes a few years before you can harvest spears without hurting the clump so in the future when a better variety is developed you will need to plant and wait years before you can harvest. At that time you can decide if you want to remove some of your current bed or start a new one. You only want males - but like with my plants, just because you buy males and plant males doesn't mean you'll be growing males. A few plants may become females in the long run. Males are better for the home garden than females (males don't waste energy making seeds). Once you taste fresh asparagus you'll wish you had a larger bed to grow it in.