All that is really necessary to amend existing soil suitable for the widest range of plant choices is a good qaulity compost. Compost both aerates (makes soil "fluffy"), helps to retain moisture while improving drainage and adds a rather wide range of plant nutrients.

If you don't have enough of your own compost, I'd investigate purchasing some commercial compost. Composted manures can be of value but they should be fully composted before using anywhere near edible crops. And since they tend to be of limited ingredients, they do not provide the same wide range of nutrients. Peat moss is not really that valuable an additive unless you are trying to acidify soil for something like blueberries.

The only way you will know if you need to mix in lime, wood ash, or what ever to adkust your soils pH is after a good, reliable soil test determines what that soils pH is and why.
Soils contain 3 mineral components, sand, silt, or clay which are an easy way of measuring the particle sizes with sand being the largest, silt next, and clay the smallest. Most likely, if your soil drains really well, does not hold water well, it is most likely sand. While compost, or other organic matter can help hold moisture as well as nutrients in the root zone you do nee to get the level of OM up to 6 to 8 percent. Perhaps these simple soil tests can be of some help,
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains� too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

Those, along with a good, reliable soil test, will help you find out what you need to do to make that soil into a good, healthy soil that will grow strong and healthy plants.

Thanks for these amazing responses, especially Kimmsr! I'm going to read through them again and go out to test the soil. So far, it's clear that my soil is too dense and dry. I'm also surprised about the peat moss. I have blackberries so this should at least come in handy for planting those. Thanks so much everyone!

sphagnum moss is a genus of 150 mosses.
They can hold 16-26 times their dry weight in water.
That is why they are harvested & use in container & garden planting. They will finish rotting with time in the soil & add to the organic matter.

If you are handy with a shovel.
You might consider burying some stumps in the ground, right under where you will grow the vegetables.

I planted some vegetable over stumps and they are doing the best by far of any in my gardens.

Here is a link that might be useful: Growing over stumps

emgardener, do you mean tree stumps?? Are they still rooted in the ground? Or did you chop them down and then bury them? How are they beneficial? Thank you for your help!

emgardner is refering to a form of Hugelkultur, one way to build up the amount of organic matter in soil that can take some time to see results.

Our ancestors would have found hugelkulture pretty amusing, since what they did with most of their time and labor was drag immense amounts of wood out of the way of growing crops, and burnt giant stumps of chestnut and other climax hardwoods in the ground.

Second the advice to do have a soil test done. It's almost always safe to add copious amounts of compost to soil, but once you start thinking about lime, fertilizer, etc., it's always good to know what you're starting with.

Need to know more natural history. Do you live near any large lakes? Was your soil ever a lakebed? Are there mountains nearby? Do you have rocky soil, with lots of small stones that might have been deposited by glacial run-off? Are there sea-shells, or sea shell remnants, in your soil? Are there any forests in your area? If so, do you have evergreen trees, or hardwood? If there is farming being done in your county, what is the main crop?

KendraSchmidt,

There are some long threads and advice on hugelkultur at permies dot come. It does help out immediately the first year I found. In a recent posting I showed a video of what the roots of a squash plant did as they grew into a hugel bed.

Here is a link that might be useful: Vegetable root excavation