I've got basically pure compost in raised beds; added some gypsum and some osmocote- type granulated fertilizer to the ones at home. Aside from other mixtures in fabric pots, that's the only medium I've grown in until this year. Never tried it in buckets or similar containers.
The Community Garden I belong to, that's all they let us grow in...16x4' raised beds filled with what they call "organic mushroom compost" but I don't think that's what it really is. I've seen three shipments of that stuff come in so far; first year's was old and well-composted. Last year's smelled rank and was still "hot" when we got it. Boy, it smelled bad! And it burned some of my plants up a bit at plant-out. This year's still smelled like it might be hot, but the plants seemed unfazed by it.
When I say I don't think it's actually organic mushroom compost, what I mean is, we get it from the City of Camden's Children's Gardens, with whom we partner, and it seems to be similar to the stuff you get from a lot of urban composting centers. I suspect it comes from the Philadelphia composting center, originally. Seems like it is mostly leaf compost with other stuff thrown in... Some woodchips, kitchen scraps, actual garbage. Like, I always find latex gloves and plastic food wrappers in the pile. But it is light and airy like real mushroom compost is. When we started a farm/garden at work, we spent the money to have mushroom compost delivered so I know what that stuff is like. Very light and well aerated just by its structure alone, with zero plastic or rubber garbage included. Both the "real deal" mushroom compost and the stuff we get from the 'hood both drain very well in the context of raised beds.
(Fwiw, we do "make" our own compost at the Community Garden, mostly from the remains of last year's plants, leaves, and any other discarded plant material. Tom, the compost guy, refuses to add weeds bc he feels like they'll just seed more weeds once we put the compost in the beds. My feeling is, if the weeds haven't gone to seed yet when I pull them, there's no risk. And, even if they have gone to seed, most of those seeds will not be viable once they break down... And even if they are viable, so what? The Community Garden is already a weed factory, running at 100% capacity. What harm would some weed seed in the compost do? But, when in Rome, I compost as the Romans do. Long story short, that homemade compost, once it's broken down, is good shit. Full of the right microorganisms, seemd nutrient rich, and it definitely doesn't get muddy. Drains out really quickly after a rain...)
I'm not complaining; beggars can't be choosers. I've gotten to use yards and yards of the stuff for nothing more than the $20/year membership fee.
This year, I built new raised beds and I filled those with topsoil I had delivered by dumptruck, cut maybe 80/20 or 85/15 with the hoodrat compost. I put gypsum thru it too, but not much. In retrospect, I kinda wish I'd mixed in some perlite as well. Mostly for my piece of mind. The shitty topsoil I'd bought was madd sandy and also for rocks and bits of wood in it which seems pretty shitty but it was fairly clean and it does seem to drain well, at least in these beds.
The beds that are 100% compost, which are right alongside the topsoil/compost mix, are performing pretty much exactly as well as the the ones with the "real" soil. So far.
We'll see how they do, comparatively, as the season hits full swing.
Not sure if this answers the OP's question at all. Like solid7 said, there's a million different flavors of compost, and they have different qualities and characteristics. Composted Cowshit, for instance, turns into sandy mud when wet. I can imagine that other forms might do the same. But the stuff I've been using, it's been really good in terms of physical characteristics. I suspect it is lacking, in terms of some chemical composition. I use fertilizers to compensate for that. I'm a shitty novice grower, but I've made it work with dozens of plants year one, maybe 120 plants year two, and i have over 170 plants going this year, too. They aren't exactly kicking ass, but they are all alive, basically thriving, and producing... And I suspect that the setbacks i have experienced are due more to my foolish rookie mistakes than they are to my heavy use of compost.
Hth,
Rob
