The usual advice for sandy soil is to add organic matter, organic matter, and more organic matter. It will help a lot with moisture retention while also adding valuable nutrients.

As for purchasing topsoil...I'm not opposed to this myself, and I have done it in specific situations (usually as an addition to a raised bed), but what gets sold as "topsoil" varies a lot, so it might or might not be worth it to do so. You might find that your money and labor are better spent elsewhere.

Another thing I might consider, though I know that many here will be opposed to the idea, is working in some peat. The things I like about it are that it's really cheap per cubic foot, it breaks down slowly, and it helps a lot with water retention. HOWEVER, it has some downsides, such as being quite acidic (I also add lime when I use peat), it won't add any nutrients to the soil, and some people have concerns about how renewable it is. If I were going to use peat, I would use it just one time, as a means of quickly and relatively cheaply improving your water retention situation, while also adding more nutrient-laden organic matter every year (or multiple times per year) in a longer-term plan to improve your soil.

Are you buying your composted manure at a garden store, or are you getting it for free from a farm? With a bit of asking around, you can often find free sources of organic matter, and when you need a lot of it, year after year, that's a fine thing indeed.

I have used a lot of local peat moss along with sand and all mixed well with good top soil...plus lots of organic matter...love, love it.

I don't know how long you'd need to age it, but it's certainly so that if it still resembles manure, it's probably too fresh. You could add some leaves to it and get it composting, perhaps, and that might speed up the process.

"You can cut green manure in the soil & plant harvest in 90-120 days."

...and that depends upon the food having direct contact with the soil or not.

Lloyd

I worry about fresh manure, or anything with a high nitrogen content, impeding germination if you tried to direct-seed too soon after working it into the soil, and I worry about it "burning" the plants if you aren't careful about how you apply it post-germination.

I don't know how long you'd need to wait before direct-seeding. My great-grand-aunt, with whom I spent many childhood years, put fresh horse manure on the fields in the Fall, let it sit under the snow all Winter, and plowed it under in the Spring, so I guess that's my personal standard for "long enough." Less time might work as well, depending on the weather and other factors, but I don't have a good sense for it.

Careful side-dressing of existing plants could probably be done without harm to them, but I think "careful" is key. Put it too close, and you'll do more harm than good.

[Yes, it's true, I was taught to garden, in part, by someone who was born in the 1800s...and sometimes I think it shows.]

That may be true if needed micro and trace elements are already there.

Lloyd

After 3 years of laying down HEAVY layers of mulch -- mainly leaves and grass clippings -- with a resort to pine straw when I run out of leaves -- and putting compost in ever planting hole/trench I am starting to see some improvement in soil quality.

Beware of buying "topsoil". If its not being trucked in from an area with different geology you'll probably get the exact same thing you've already got. DH bought material to fill 3 raised beds that was supposed to be 50% topsoil and 50% compost. The reality was a mix of the exact, same, worthless sand we already had with well-aged wood-chip mulch.

Be sure to get your soil tested (free or inexpensive via the county cooperative/ag extension), so that you know what mineral deficiencies you have to work with.

As a side note, I'm finding it helpful to plant my individual plants and my "hills" in shallow pits (dug out twice as deep as necessary and filled with compost beneath the actual planting soil). Likewise, I made trenches to plant the things that go in rows.

I often do have leaves to shred with it but not always. The stable bedding will heat up fine and compost without any additives. I do send the stable bedding through the shredder which helps it break down faster then it otherwise might.

I do put a lot of labor into it with turning and rehydrating but I get usable compost from it in as little time as a month. I put it through three heat cycles turning and re-mixing between each, and then put it aside for another week or two to finish. At this point the stuff is full of worms so that tells me it has been burned and churned enough to be put to use without worries about burning roots.

This stuff makes an excellent feeding mulch. I also use it as a large percentage of my container soils. I do mix bunch of vermiculite into it for the containers so it doesn't get too heavy or soggy.