Biochar and PH problems

DonBrennon

DonBrennon

Well-Known Member
Any biochar users experienced ph problems after adding biochar?

I've been experiencing some lockout due to high soil ph and have been dumbfounded as to what could have caused this..................well I've had some of my latest batch of home made biochar 'charging' in a mix of wormcompost and amendments and out of interest decided to test it's ph. The liquid in the vial of the sample tested almost turned blue, never mind dark green, indicating really high ph. I know that my castings are on the acidic side and the amendments cycling should make the mix more acidic as no liming/ph buffering ingredients were added. I've always assumed that biochar was ph neutral, but I've just been doing a little reading and have found that it can vary wildly and can be as high as 10. So my biochar must have high ph, directly affecting the castings around it.
 
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DonBrennon

DonBrennon

Well-Known Member
I was hoping that this biochar/vermicompost mix would be acidic and I use it to cut my already high ph soil to balance it out.

Would adding some yellow sulfur to this mix and letting it sit for a couple of weeks bring the ph down?

Or do you think I should use gypsum? but I do only have the pelletised form so it would take ages to break down, perhaps I could get the pestle and mortar on it, even then would it break down fast enough?
 
testiclees

testiclees

Well-Known Member
No my dude. Most biochars are high pH because of ash content. Some chars are up to 80% ash. The source material and the pyrolysis technique also affect the pH.

I've used biochar on and off for a while. I get finest results by giving the char an extended charge period outdoors hitting it with a variety of dressings as time passes. Ive got a current batch of biochar that Ive been charging for a couple months. I bubbled it with straight peat right from the get go. then i dumped it in a big fabric pot and topped it with light chicken compost, seaweed meal, minerals and mulched with alfalfa hay. I let it sit outside and get rained on. It's leachate is coming out just under 7 after about 10 weeks.

If you've got some time to get things in order you might try a fishy fert that is preserved with phosphoric acid. The low pH of that type of fert will help drop the biochar pH to a degree.

I think the wisdom of adding gypsum is gonna depend on where your soil stands with Ca and K. I think straight S could give you a problem by forming toxic sulfuric acid.
 
greasemonkeymann

greasemonkeymann

Well-Known Member
DonBrennon said:
I was hoping that this biochar/vermicompost mix would be acidic and I use it to cut my already high ph soil to balance it out.

Would adding some yellow sulfur to this mix and letting it sit for a couple of weeks bring the ph down?

Or do you think I should use gypsum? but I do only have the pelletised form so it would take ages to break down, perhaps I could get the pestle and mortar on it, even then would it break down fast enough?
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did you rinse the biochar after breaking it down?
I use biochar to help control the typical acidity issues that can come up in indoor container growing, but I always rinse as well as charge it, so maybe that's the difference?
and also what is your soil PH?
 
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greasemonkeymann

greasemonkeymann

Well-Known Member
DonBrennon said:
I was hoping that this biochar/vermicompost mix would be acidic and I use it to cut my already high ph soil to balance it out.

Would adding some yellow sulfur to this mix and letting it sit for a couple of weeks bring the ph down?

Or do you think I should use gypsum? but I do only have the pelletised form so it would take ages to break down, perhaps I could get the pestle and mortar on it, even then would it break down fast enough?
Click to expand...
I would speculate based soley on the inputs that most wormbins would probably be a lil acidic, I wouldn't add gypsum to counter anything, hard to control the release rates and such, may create MORE problems
 
MustangStudFarm

MustangStudFarm

Well-Known Member
greasemonkeymann said:
did you rinse the biochar after breaking it down?
I use biochar to help control the typical acidity issues that can come up in indoor container growing, but I always rinse as well as charge it, so maybe that's the difference?
and also what is your soil PH?
Click to expand...
I charged my bio-char with fish emulsion, I cant figure out what else to do with the emulsion, but it came out smelling like ammonia? Does that sound right?
 
DonBrennon

DonBrennon

Well-Known Member
greasemonkeymann said:
did you rinse the biochar after breaking it down?
I use biochar to help control the typical acidity issues that can come up in indoor container growing, but I always rinse as well as charge it, so maybe that's the difference?
and also what is your soil PH?
Click to expand...
Well, the current soil which has a ph of between 7-7.5, has had 3 different batches of char added. The 1st was a 'horticultural' grade bag bought from an online organic shop(very expensive), pre charged and ph balanced at 2% of my mix. Then I re-amended the soil and added my own char which was not rinsed, but soaked in a mix of water, alfalfa and kelp meal for a week. This brought it up to around 5% of my soil mix, but I think it was the 3rd addition bringing the percentage to around 10%, which has caused my problems. This batch was charged with wormcastings and amendments like the one I'm currently doing and must be the source of my high soil ph and neither of them were rinsed.............shit
 
DonBrennon

DonBrennon

Well-Known Member
greasemonkeymann said:
hmm, well I'm not sure
fish emulsion usually just reeks of fish
a good easy way to charge biochar is with urine
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The char/castings mix is currently in a 10 gal bin in an out house and I have pissed in it a few times when I've been watching the footy with a few tins and couldn't be arsed going upstairs lol. Do you think if I kept pissing in it, it would drag the ph down?
testiclees said:
No my dude. Most biochars are high pH because of ash content. Some chars are up to 80% ash. The source material and the pyrolysis technique also affect the pH.

I've used biochar on and off for a while. I get finest results by giving the char an extended charge period outdoors hitting it with a variety of dressings as time passes. Ive got a current batch of biochar that Ive been charging for a couple months. I bubbled it with straight peat right from the get go. then i dumped it in a big fabric pot and topped it with light chicken compost, seaweed meal, minerals and mulched with alfalfa hay. I let it sit outside and get rained on. It's leachate is coming out just under 7 after about 10 weeks.

If you've got some time to get things in order you might try a fishy fert that is preserved with phosphoric acid. The low pH of that type of fert will help drop the biochar pH to a degree.

I think the wisdom of adding gypsum is gonna depend on where your soil stands with Ca and K. I think straight S could give you a problem by forming toxic sulfuric acid.
Click to expand...
Thanks for the advise, I think I'll mix this batch into my compost pile when I get it going, hopefully a hot compost with plenty of good amendments will make it less alkaline.
 
DonBrennon

DonBrennon

Well-Known Member
Mmmmnnn..............another thought is my acidic worm bins???? I do add oystershell flour and ground egg shells, but they still get quite acidic, maybe add a hand full to each bin, what do you think? When I sift for castings the bigger bits will go back into the bin, while my casting would be pre-loaded with the smaller char particles
 
testiclees

testiclees

Well-Known Member
DonBrennon said:
Mmmmnnn..............another thought is my acidic worm bins???? I do add oystershell flour and ground egg shells, but they still get quite acidic, maybe add a hand full to each bin, what do you think? When I sift for castings the bigger bits will go back into the bin, while my casting would be pre-loaded with the smaller char particles
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If youre sure the vermicompost is reasonably acidic it isprobably worth a try. What about just mixing in some peat? Brown peat moss that is available around here has a pH about 4-5. Its cheap and works quickly. I used about 6 dry gal of peat to 2gal of unrinsed biochar. When i soaked the peat and biochar together i poured the water off 2x.

Biochar does have several benefits as a soil amendment but one of its most desirable benefits is the liming effect on acidic soils. Because of this effect it isnt as much of a no brainer when soils are already in the zone.
 
DonBrennon

DonBrennon

Well-Known Member
testiclees said:
If youre sure the vermicompost is reasonably acidic it isprobably worth a try. What about just mixing in some peat? Brown peat moss that is available around here has a pH about 4-5. Its cheap and works quickly. I used about 6 dry gal of peat to 2gal of unrinsed biochar. When i soaked the peat and biochar together i poured the water off 2x.

Biochar does have several benefits as a soil amendment but one of its most desirable benefits is the liming effect on acidic soils. Because of this effect it isnt as much of a no brainer when soils are already in the zone.
Click to expand...
That's what I've just been doing lol, cut it with about 20% by volume with peat and added some more amendments, 1/2 cup each of kelp, neem, alfalfa, fish meal and a bit of humic acid powder. I'll keep turning it to keep it aerated and check its ph in a week or so to see if its had any effect.
 
MustangStudFarm

MustangStudFarm

Well-Known Member
DonBrennon said:
Mmmmnnn..............another thought is my acidic worm bins???? I do add oystershell flour and ground egg shells, but they still get quite acidic, maybe add a hand full to each bin, what do you think? When I sift for castings the bigger bits will go back into the bin, while my casting would be pre-loaded with the smaller char particles
Click to expand...
I was not telling you to make soap or anything. If you know anything about lye, it would give you a better understanding of the PH that it brings... I took a little college chemistry and enjoyed it!
I read an article that talked about wood ash and worm bins, a very small amount could help adjust the PH. I know that wood ash does have potassium and the lye is actually a potash lye, potassium hydroxide. Calcium hydroxide is what you would see in a drain opener and is the common lye, NaOH...

WiKi:
Potassium hydroxide, or caustic potash, is used in a wide variety of industrial applications. The major uses are in the production of potassium carbonate, potassium phosphates, liquid fertilizers, and potassium soaps and detergents.


This does not mean that I know how to use it effectively!!!
 
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