Organic Soil Moisture Management

[SpicySativa]

What's up organic heads?

I've been thinking a lot lately about soil moisture management in my setup... Currently I'm using 7-gal Smart Pots full of my organic mix, which I hand water every 2-3 days (when the pots are noticeably a little lighter, but definitely not dry). I've been noticing that any roots which grow out into the outer inch of the pot end up drying up and dying even when I'm watering every other day while the pot still feels heavy. I have LOTS of airflow above and below the canopy (PM prevention) which I'm sure contributes to the soil around the edges drying out quickly.

I also notice that even when I hand water very slowly a little at a time, a significant amount of water channels through the soil and drains without soaking in. This ends up leaching some of the soluble, readily available nutrients from the soil (nitrates, in particular)...

If I take into account the 1 inch of dry dead space around the outside of the pot, plus the one inch of dry dead space at the soil surface, my 7 gallons shrinks to a mere 4.6 gallons of moist, productive soil! Thats a full 2.4 gallons of wasted potential! I feel like this very well may outweigh aeration and root pruning benefits of using Smart Pots.

It seems to me like this quick drying "benefit" may be a relic from the bottled chemical growing realm where it lets you "feed more often"...

Anyway, I think I going to make some changes for next round:

1) Step up from 7-gal Smart Pots to 10-gal plastic nursery pots.

2) Cover the soil surface with mulch. (Pine bark fines? Coco coir?) I welcome any suggestions for the best mulch to retain moisture near the soil surface (and help in the cycling of any top dressed nutrients).

3) Install a drip system with +/- 4 evenly spaced emitters per pot. This will be plumbed directly to the outlet of my Small Boy dechlorinating filter, and controlled with an inline irrigation timer. I will fine tune this to maintain the ideal soil moisture. I believe the SLOW drip and mulch will overcome the problems of channelling, dry spots, leaching, etc, etc... Plus I'll be able to leave for a few days or a week without securing a "babysitter".

I think with these three changes I will provide my roots with a greater volume of moist, healthy, living soil.

What do you guys think? I welcome any thoughts or suggestions regarding this plan or anything soil moisture related.

Cheers,

-SpicySativa

 

[DabSnob]

A few questions,
1) is this an indoor grow?
2)how long are you veging?
3) whats your strains flowering time?

With air pots and smart pots the roots on the very outer edge are suppose to die back into the pots. This is called air pruning, this creates a larger root system inside the pot instead of on the outer layer.
As for watering every 2-3 days in 7 gallon pots, i would wait for those things to dry out completely.General rule of thumb is only water with as much water as they will use in 48-72 hours. in my grow i grow my plants in 3gallon pots from clone to finish and i water every 4-6 days in veg and every 2-3 days in flower. in my experience its much better to allow the pots to dry out completely and water 8oz at a time as slow as possible for the first gallon or so. i dont recommend having your pots moist 24/7 but if thats truely your goal, use a potting mix with less perlite,vermiculite, etc... will do what your looking for.

 

[SpicySativa]

A few questions,
1) is this an indoor grow?
2)how long are you veging?
3) whats your strains flowering time?

With air pots and smart pots the roots on the very outer edge are suppose to die back into the pots. This is called air pruning, this creates a larger root system inside the pot instead of on the outer layer.
As for watering every 2-3 days in 7 gallon pots, i would wait for those things to dry out completely.General rule of thumb is only water with as much water as they will use in 48-72 hours. in my grow i grow my plants in 3gallon pots from clone to finish and i water every 4-6 days in veg and every 2-3 days in flower. in my experience its much better to allow the pots to dry out completely and water 8oz at a time as slow as possible for the first gallon or so. i dont recommend having your pots moist 24/7 but if thats truely your goal, use a potting mix with less perlite,vermiculite, etc... will do what your looking for.

Thanks for the reply.

This is an indoor grow, and I veg to about 16-18 inch bushes. I rarely run the same strain twice, so flowering times vary.

You don't want to allow living soil to dry out completely. Not only is this detrimental to the microorganisms in the soil, it also tends to create a hydrophobic crust that makes it difficult to wet the soil evenly.

I understand air root pruning (why I switched to Smart Pots about a year ago), but this 2.4 gallons of dry dead space isn't doing me any good. Waiting even longer to water, as you recommend, will just result in even MORE unproductive soil around the edges.

I very rarely feed liquid nutrients, so I need my soil organisms to be operating at peak potential for nutrient cycling, which requires moisture.

Thanks again. Keep those comments coming!

 

[SpicySativa]

A little more info...

My "soil" is composed of roughly equal parts Alaska Peat, perlite (and pumice), and worm castings. It has been reammended and recycled numerous times now. The soil is alive with bacteria/archae, fungi, soil mites, springtails, and red wiglgler worms (accidental carryovers from my worm bin that seem happy as clams living and reproducing in my pots).

This isn't the kind of soil you can let dry out completely. It's gotta stay moist.

 

[OrganicOzarks]

Mulch will solve your problem. I use coco chips for mulch, but I am going to switch to hardwood mulch because it is much cheaper. I also recycle my mulch, and keep using it over and over.

I only water on Monday, and Friday, and my pots never dry out. I use 3 gallon, and 5 gallon smart pots. The three gallon pots only get 2 beer cups worth of water on each watering. The 5 gallons get 4 beer cups each watering.

Can't get much easier than that.

 

[OrganicOzarks]

I forgot to add that I recycle my soil as well. I add new compost, and worm castings after each run, along with some new amendments.

 

[DabSnob]

ahhh, then using larger pots and Mulching the top layer would serve you well. this will be my first round recycling my grow medium, im excited to see the difference as well as save me some money! good luck and happy growing

 

[SpicySativa]

Alright! Productive evening!

I got a fresh, on demand supply of dechlorinated/dechloraminated water plumbed into my grow cabinet, and 1/4" drip tubing run to each plant (split to 4 emmiters per plant for better coverage). I didn't install an inline irrigation timer yet. For now, I'll just "manually" water by cracking the valve a little for a nice slow, even soak. MUCH easier and less messy than filling a bucket in the bathroom, walking it across the basement, and hand watering with a cup.

I also plumbed a separate "tap" with a valve into the cabinet. I can use that to wet down the soil surface, rinse out my trays, etc. Combine that with my "Bucket Head" wet vac and I'm in business.

 

[al-k-mist]

drunk but check it
i knw everyone says pH aint a prob w organics, but adding pine bark, r fir bark, eyc is super acidic, ie blueberries but not cannabis
each grow is dif and i aint gonna askk temp, fans etc, as i am no expert,,,jedi but not expert
i water every day, but its 125+ gal, greenhouse, but airflw temps humidity all play a part
is it possible to water every day, by hand? or set up automatik?
peace

 

[Carlos Danger]

Alkmist, having grown up on pine sands I'm gonna argue this one with you a bit. Pine fines and bark get an unfair rap that they shouldn't be composted or mulched because they make the soil acidic, but most of the original sources for this advice weren't considering that soil isn't acidic because pine forests grow on it, pine forests grow on it because the soil is acidic. I've been mulching thickly with ground/chipped pines and using pine needles in mulch for years with no detriment. It all breaks down to closer to 7.

Mulch is a game changer, you should definitely be doing it spicy. It keeps the important top couple inches moist for longer and helps diversify your soil life. My deep mulches always break down before a cycle is over, which surprised me the first time I saw it happen. The worm populations in my containers also benefited - I noticed more worm activity in the tops of these bins.

 

[OrganicOzarks]

Alkmist, having grown up on pine sands I'm gonna argue this one with you a bit. Pine fines and bark get an unfair rap that they shouldn't be composted or mulched because they make the soil acidic, but most of the original sources for this advice weren't considering that soil isn't acidic because pine forests grow on it, pine forests grow on it because the soil is acidic. I've been mulching thickly with ground/chipped pines and using pine needles in mulch for years with no detriment. It all breaks down to closer to 7.

Mulch is a game changer, you should definitely be doing it spicy. It keeps the important top couple inches moist for longer and helps diversify your soil life. My deep mulches always break down before a cycle is over, which surprised me the first time I saw it happen. The worm populations in my containers also benefited - I noticed more worm activity in the tops of these bins.

I agree with the pine tree statement. I am surrounded by pine trees, and the truth is that most of what you here about the acidity issues is false. You can use pine bark fines in a soil mix, and you won't have any issues. You can use pine bark fines as mulch, and you won't have any issues. The statements about having acidity issues from using pine products is flat out wrong.

 

[EclipseFour20]

When using bark, make sure it is fully decomposed--most are "green". I tried various commercial barks--and so far I found "orchid bark" working the best for me: small sized, fully decomposed and "affordable" ($8 for 4 cuft).

Don't forget to calculate the air & water porosity, and absorption rates of your "custom medium".

"A good medium should drain rapidly after irrigation, and should ideally contain 10% (by volume) or more air space after draining (Table 2). Oxygen stress conditions are likely to develop at values lower than 10%. At the same time, a good medium should contain at least 50% water (by volume), and available water should be at least 30% (by volume)."

How to calculate these? This two page "Fact Sheet" from Rutgers explains how. Do a test and see how out of whack your soil is or is not.
https://njaes.rutgers.edu/pubs/publication.asp?pid=FS881

Good primer on container medium porosity...https://njaes.rutgers.edu/pubs/publication.asp?pid=FS812

And...a good primer on growing medium aggregates is...http://www.fao.org/hortivar/scis/doc/publ/8.pdf

Adjust the mix, conduct porosity/absorption tests, adjust mix, conduct tests...adjust mix, conduct tests...and eventually you will have a perfect medium.

BTW...don't forget to ph test too!

 

[xmobotx]

there's a thread somewhere on icmag where the guy recommends trays of drainage material {like perlite, pumice or, lava rocks {lava rocks seems like the best choice} then having a layer of water in the tray to just under the top of that drainage layer ~setting smart pot-type fabric pots on such mechanism is supposed to give an auto-water effect

bear in mind that i haven't tried this ~just read that thread some time????

anyway; whether it functioned as "auto-water" or not; it would help to keep that outer region hydrated & {@ least according to that OP;} may even provide you w/ a SIP-like auto watering system

thanks for reminding me; it's something i would like to experiment w/

 

[Oregonism]

Mulch will solve your problem. I use coco chips for mulch, but I am going to switch to hardwood mulch because it is much cheaper. I also recycle my mulch, and keep using it over and over.

I only water on Monday, and Friday, and my pots never dry out. I use 3 gallon, and 5 gallon smart pots. The three gallon pots only get 2 beer cups worth of water on each watering. The 5 gallons get 4 beer cups each watering.

Can't get much easier than that.

Hardwood mulch is a great recycle. How about shredded newspaper? I use it to block the sun and keep evapostranspiration down. Easy fix for me.

 

[dank.frank]

Blumats.



dank.Frank

 

[vonforne]

I am growing in 7 gallon smarties now and I have 6 of 10 with BluMats. The ones with the Blumats are doing slightly better.

Try them. Here is the link where I purchased mine. Blumats

 

[VerdantGreen]

i stopped using airpots for this reason, i figured that i was losing soil volume because the outside layer was dry. also its a pita that the water p1sses out of the holes. too many entry points for gnats etc etc

(i get mixed up between airpots and smartpots but the dry soil issue remains the same.)

airpots made no difference to my yields whatsoever.

VG

 

[SpicySativa]

Thanks for the suggestions, guys. I thought a lot about the Blumats, but I don't like the fact that I'd have to pull and shove the carrots, plus readjust them each time I need to take my plants out of the cabinet for inspection, foliar sprays, training, etc.

I think this drip system I put together will do the trick once I get it dialed in. For now, I'm just operating the drip manually to get a feel for how to set the irrigation timer.

 

[Mr. Krinkle]

i stopped using airpots for this reason, i figured that i was losing soil volume because the outside layer was dry. also its a pita that the water p1sses out of the holes. too many entry points for gnats etc etc

(i get mixed up between airpots and smartpots but the dry soil issue remains the same.)

airpots made no difference to my yields whatsoever.

VG

^^^ im with this guy

 

[SpicySativa]

I think I'm still going to start my plants in 1-gal Smart Pots for a couple weeks. This way I can get some root pruning benefits early on. I don't think I'll be flowing in Smart Pots anymore. Now to find some drip saucers that'll fit a 10-gal nursery pot...