When to restart no-till pots

Hey all!

I’ve had my no till 20 gallon pots going for a little over a year. The quality has been consistent and amazing, however I’m noticing my yields are tapering off (I’m averaging .6 gpw, yikes)

I always add more pumice and rice hulls when I topdress to avoid compaction but I know I’m going to have to dump and remix soon. How often do you guys do this?

What are you topdressing with? How many grows did you do within that "little over a year"? Cover cropping? ... with what? Have you tried to dig down a bit to check on the health of worms and stuff? I have a vegetable garden bed behind the house that hasn't been disturbed in 6 years now, and it just keeps getting better. I've only gone 3 grows in a row so far with pots indoors growing cannabis, but I can't see any reason why we can't duplicate indoors what happens in those vegetable beds outside.

I’d say they’ve had about 5 or 6 grows in each pot. I have dug down and find worms still crawling around so they’re still kicking. I use clover for cover crop. I topdress with equal parts alfalfa, kelp, fish meal, fish bone, crab meal, OSF, basalt, glacial rock dust, neem, Karanja, insect frass. Then I mix in pumice and rice hulls. I usually topdress 1 cup of this mixture every 3 weeks and then sprinkle castings over it.

Like I said quality is great but I keep getting less and less yield. I guess I just don’t know what to look for or how to judge when I should dump and start over, i know I’ve read that it needs to happen eventually especially in smaller pots like mine. When I started them each plant regardless of strain was getting 7-8 oz per plant and now It’s 3-4 per plant.

Ouch, that's quite a yield reduction. It would be very interesting to find out why. Plants still grew healthy looking? First thing I'd do is get a soil test, with potential (total) and immediately available nutrient levels. But 6 grow cycles is more than I currently have experience with in indoor pots. One of the issues we face is using 100% biomass for our "base". Peat moss and coir take awhile to break down, but once your worms have at it, the texture will change as it goes through its various stages of decomposition over time. Being so high in carbon, I'm sure the bacteria who do eventually munch on it need a side-dish of nitrogen. Usually it goes so slow that very little precious nitrogen is locked up when this goes on, but at a certain stage its decomposition seems to accelerate. Ditto for carbonaceous rice hulls too. But it seems you're top dressing with a lot of heavy nitrogen amendments, so carbon:nitrogen ratio isn't probably the issue with your top dress.

You could have a build up of organic matter deep in your soil if the roots of the previous grow were not completely decomposed when you harvested the next - leading to more root matter (alive or dead) accumulating faster than the soil life (worms, fungi, and bacteria) can consume them. That could lead to anaerobic conditions deep near the bottom of your pot, where red wiggler worms don't like to travel. That could also lead to watering issues I'd think with all the undecomposed knots of roots that accumulate down there. Maybe none of this is relevant to your case. I'm just throwing things out there. Lol

OP same thing happened to me about a year in doing the same things as you. Checked my soil pH: alkaline. Made new soil and yields went back to normal. Well one year later, soil pH is raising again. Trying out some elemental sulfur this next run. Hear it takes a few weeks to start working.