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How deep do Aerobic bacteria Go in the Soil ?

St. Phatty

Active member
I was talking to a grow store manager recently. He has a science background it sounded like, and he surprised me by saying that there's no need to have Fertilizers like Bat Guano deeper than 6 inches.

Because that top 6 inches of soil is where the aerobic bacteria is, he said.
The aerobic bacteria being the bacteria that digest the bat guano, part of the (aerobic) Micro-herd that deliver nutrients - their excretions - to the roots of our favorite plants.

He said that deeper than 6 inches, in the normal grow set-up, the bacteria are anaerobic, and don't convert the bat guano into something the Cannabis plant can consume. So there's no need to mix bat guano into the soil deeper than 6 inches. He said.

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That picture is a gray scale of part of the 22 acre Sonoma Compost facility. I took a class from Will Bakx, the Technical Director at Sonoma Compost.

The tour of their facility was one of the coolest industrial shows I've ever seen. Those wind-rows are 200+ yards long. 25 to 30 feet wide, 12 to 15 feet high. All cooking at about 160 degrees F.
That's where they need Will. The mix has to be very precise in order to get the 160 degrees F. Water is also an essential ingredient. Without water it doesn't heat up.

The aerobic bacteria need water to de-compose the yard waste (leaves & grass clippings) and ground up chickens and chicken feathers that are the standard inputs for industrial hot composting operations.

It is region dependent. Sonoma Compost has access to tons of mallard duck poop, so that goes into one of their mixes to augment the Phosphorus and Potassium.

I mention Will in the context of the statement about aerobic bacteria only going 6 inches deep, because the windrows at Sonoma Compost are 12 to 15 feet high, and it's all aerobic bacteria that are producing those temperatures. So there is a case of aerobic bacteria 12 feet deep.

It would be great if we could watch Will and the grow store manager debate this and sort it out.

Side-stepping the exact depth of how deep you can find aerobic bacteria doing good work in Cannabis gardens, the one take-away from talking to the Grow Store Manager is -
AEROBIC BACTERIA ARE GOOD.

Imagine planting Cannabis plants on top of almost finished wind-rows 10 feet high. I say almost finished because after 10 weeks, the compost they sell is sometimes still steaming. The aerobic bacteria are still doing their thing.

That's what I'm talking about planting in. If Aerobic Bacteria are Good, wouldn't you want to design your soil base so that it was ALL Aerobic Bacteria ?
 

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Easy7

Active member
Veteran
Hydro guys aren't pros or soil scientists, that's why they work retail.

Some truth to it though. O2 only gets so deep so fast.

Fact is a lot of organic nutrients, like guano, have water soluble nutrients. When making tea, people compost the h2o insoluble. Only focusing on the soluble.

Digging in guano deeper than 6" is more of a concern of disturbing feeder roots.

Can't really control which bacteria grow. Not without a lot of effort. Can sway the micro-battle a lot though.
 

St. Phatty

Active member
I'm realizing the designers of the special grow pots I see advertised, the ones with holes in the side, are focussing on grow factors like aerobic bacteria.

I might make some of my pots out of non-galvanized wire mesh this summer.

So that the sides of the pot are mostly air.

I already did that with a plum tree, and it's taking - rooting - growing.

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That shows the wire mesh pot construction.

It also shows one other aspect of aerobic soil bacteria - when they are really doing their job, the soil volume decreases.

That plus the natural soil settling that happens ... when I first set up that plum tree, the soil was about 8 inches higher.

My Cannabis plant mix is basically a worm compost pile mixed with forest humus. 2 years ago it started out as plain old Foxfarm Ocean Forest.
 

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Easy7

Active member
Veteran
Just my opinion, but I see no reason to force a healthy ecosystem.

There are parasitic life forms that a balanced eco sytem keeps in check. The idea of organic and living is there is more disease, yet also more disease inhibiting life forms.

Nothing bad is going to grow because roots are deep in the ground. I'd be more concerned about messing with balance and not seeing all the ramifications. But the top 6" is where most of the life is. Yet there is still life below. Rain water brings o2 deep into the soil.
 

djimb

Active member
Veteran
I would think aerobic bacteria would be anywhere there was sufficient oxygen. In the ground, 6 inches sounds about right, that's about the depth of topsoil, but compost piles and pots are a different story.

Those compost piles are full of aerobic bacteria because they're being turned frequently. In a nursery pot, I'll bet you'd find aerobic bacteria at a decent distance from the top and the drainage holes, an air pot, as has been mentioned, would probably only go anaerobic in the center of the rootball.
 
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