Sue, I apologize. My bed-side manner is sometimes less than tender. There is no doubt that "bubbling buckets of futility" rubs many readers the wrong way.
Let's talk about that "crust" that you wanted to prevent with mulch or a cover crop for a bit though. That mat is very important and desirable.
Trust me, I understand the value of mulch and love it for long-term soil building. Never mind that, lets talk about the "crust."
Fortuitously, I harvested a big plant a few days back out of a 10 gallon container. What was left was a skeleton sticking up out of the pot. It had just been sitting out on the deck for a few days. I went out and grabbed the trunk and lifted it. The plant didn't break loose. I tried jumping up and down like a kid on a pogo-stick to dislodge it. No dice... Stuck my foot on top of the pot and pulled hard. Riiiiiip.
What we you are going to see is a cross-section of Main Street. The business district. The hub of trade and commerce. Most of the action going on is in the first few inches of soil. What is down low is important, too. Things move more slowly down in the deep dark. There are transactions taking place but the pace is different. It is the gradual transition from an aerobic to anaerobic environment as we get deeper and darker. Down there we enter a sort of nether-world...
Never mind that, lets look at pictures of Main Street. You can see the "crust". It is about 1" thick.
I really like the last picture. While it is not exactly true to say that the juncture where the plant/root complex broke away from the "anaerobic" nether-world is definitive it is good enough for what I want to try to explain here. That crust is a hotbed of microbial activity. The chemical reaction kinetics in the crust; they are going on at an exponentially greater rate than those below it. When I top-water the metabolites from the crust are rinsed away and drain into the lower rootzone. It takes a while to get the crust hydrated when you start watering. Go slow.
Looking below the crust we can see that there is no dirth of life down there. CTRL + + +
Anyway, late in the cycle I like to break up that crust and add easily metabolized whole food to it. The "crust" is back in a day or two. That wouldn't be possible if there was a cover crop or mulch there, would it? A tablespoon of alfalfa meal scratched into the "crust" is going to supply more nitrogen in two weeks to the plant than clover or lambs quarters will in a year. Sorry. That's just the way it is.
We are feeding pigs in a pen when we grow heavy feeding plants in a pot.
A bubbling bucket of futility is more likely to upset the healthy community going on in the crust and what lies below than help it. It's like dumping a population of refugees into an already burgeoning community.
Don't get me wrong. I have a substantial permaculture background and know a thing or two about using mulch, cover crops, compost and water management to revitalize troubled landscapes. When doing so I use all of the "4th grade science class" agricultural basics that the no-till community tries to apply to raising pigs in a pen.
Cannabis is a HEAVY feeding annual with an explosive growth rate. Treat it as such. It isn't that hard to grow very high quality, metabolically healthy organic pot plants unless you make it hard and complicated. Feed the soil that feeds your plants with healthy easily metabolized whole foods and throw the bubbling buckets of futility, sprouting -> grinding ->straining seed sqeezin's, and other sundry Dr.Ozshite in the rubbish bin.
What is going to happen to the $12 pot of used soil? I think in this case I'm going to up-can a rootbound sage plant into it.
I'm just as likely to dump it around the rootzone of a tree I notice is struggling while out for a walk...
Anyway Sue, I know I'm being a bit of a turd. I'm like the phantom pooper who shows up and leaves a stinker in your journal now and then. You like an active journal and a little edge is good for page counts.
I hope you and others enjoy the "Main Street" picture. I wish I could zoom and zoom and zoom in and show the teaming life in there.
* Giggle *. This is so much fun. 
