When we first moved to North Idaho
and tried to garden, we thought we needed soil. What we had was gravel.
We spent a lot of time running our "soil" through a sieve to get piles
of gravel out of it. Then we started adding leaves and horse manure.
The leaves go on in the fall, and the manure in the spring. We added enough
material that now we're gardening mostly on top of our original soil.
Except for root vegetables like carrots, we don't need to till the soil,
unless tree roots grow in too much. (We never have had a rototiller--just
hand turning with shovel or spade fork) Our garden is planted mostly
in the top layer of composted horse manure. In case you didn't know,
horse manure is less likely to burn than steer or chicken manure, and has
proved to be good for all the vegetables we grow. Carrots,
though they like loose sandy soil and don't need so much nitrogen, do well
if the soil is well turned with a spade fork and not compacted.
All this is possible through having a good source of horse manure. We've got one, though we have to wait until he's ready to clean his horse enclosure, so it's nice to have an area to start on earlier. In our case we have two gardens, at our two residences, and this year we're going to see how the old garden does without a yearly dose of manure.
In case you're not so blessed with manure as we are, you can also plant in clumps or rows, putting the manure you have right where it will be used, instead of the traditional way of spreading it over the whole garden... I did that at the new garden last year, when it was in fairly bad shape. This year I'm hoping to not just put the manure in rows, but it did work...
Later I learned a similar kind of gardening has been dubbed "Lasagna gardening," due to the layers.
If you have root maggots in your area, you'll know it, as they eat onion roots and crucifers (cabbage family), and cause them all to shrivel and die. We have them in the Northwest. My organic prevention is to cut 3 inch squares of rubber inner tube material, and then cut in toward the middle from one side, halfway. Then move the scissor in to the middle and make a couple cuts going out, about 1/2 inch long--these are to allow growth expansion. The resulting cuts resemble a chicken foot. Place these around the seedlings flat on the ground as they are set out, and most of the little flies that lay the eggs will be defeated.