I've bragged/complained about the primordial ooze in my 8th acre garden, it is a fine, high-organic silt, jet black and when wet you WILL lose a shoe in it.
I haven't really done much, added 20-year composted turkey shit one year, threw a couple 60 lb. bags of sand at the low end with the hope of lowering viscosity and increasing drainage (this soil will hold water for just about ever). The sand was pretty much overwhelmed before it had a chance to do anything beneficial. That's how fine and rich this stuff is.
This year, what with all the various manner of peppers going into that dirt, I'm considering improving drainage with either perlite or peat. I could use a little helpful input. YES, I've had good harvests with anaheims and the aji lemon drops I've grown, but they started out very very slow, as if the shock of a denser medium stopped the mechanism to grow and proliferate. I wonder if better aeration could improve on the harvests I now get.
The black ooze is approximately 12 to 18 inches deep before hitting a solid and much deeper floor of pure clay, hard enough that I can't get a spade more than a couple inches into at a full swing, obviously adding to the retaining quality of my muck.