Burnt wood smell in latest batch

I’ve been making biochar in the back garden for the last few months, using a 90 liter incinerator with a 45 liter lidded steel bin inside, using scrap pallet wood as the fuel, and various types of material as the char (pine cones, pine needles wood shavings, saw dust, bones etc.)

Last week I made a batch using wood chips for the first time, and at the end of the burn, some of the chips (maybe 10%) were not fully carbonized.

I realise this was because some of the chips were damp.

I thought it would be ok, and mixed it into a previous batch in a big bucket for inoculation.

I inoculate with urine, organic chicken pellets and worm castings.

The problem I’m having is the  dry strong smell of burnt wood in this current batch.

I’m a strong believer in the old “trust your nose because your nose knows” saying, and I’d like to know if I should ditch this batch or if it will be safe to use on my garden?
I’m still adding more urine, hoping the burnt wood smell will go away.

Any thoughts?

Your nose is wise: you haven't cooked off all the tars/volatiles in that batch. Excess moisture will substantially extend the normal burn time needed to fully char the wood. Your hands will tell you too, if the char is sort of greasy when you rub it between your palms.

People barbecue on that sort of char: it's called flavour.

I would never discard a batch like that. It's a waste of effort and good materiel. It will still be gold around trees and perennial beds. Nature has been making imperfect, tarry, stinky char since it invented fire.

In the garden? I fall into the "dilution is the solution" camp. I mean, my organic carrots probably have miniscule traces of plutonium but I munch them up with great relish. Personally I would add that batch to my slow compost pile, and in a couple of years or so all would be lovely. My 2c.

Douglas Alpenstock wrote:Your nose is wise: you haven't cooked off all the tars/volatiles in that batch. Excess moisture will substantially extend the normal burn time needed to fully char the wood. Your hands will tell you too, if the char is sort of greasy when you rub it between your palms.

People barbecue on that sort of char: it's called flavour.

I would never discard a batch like that. It's a waste of effort and good materiel. It will still be gold around trees and perennial beds. Nature has been making imperfect, tarry, stinky char since it invented fire.

In the garden? I fall into the "dilution is the solution" camp. I mean, my organic carrots probably have miniscule traces of plutonium but I munch them up with great relish. Personally I would add that batch to my slow compost pile, and in a couple of years or so all would be lovely. My 2c.

Thanks for your reply.
I grow in buckets/containers, and I don’t have space for a compost heap, so it really is a case of use or dump on this occasion.

I’m putting a lot of effort into growing a bumper crop of chilies this year, so if there’s a risk of it causing more harm than good, dump may be best.

I’ve probably got about 5 weeks before needing to add it to my containers though if there’s a way to amend it?

In containers? I honestly can't give you a definitive answer. Especially not from afar.

Me? If the smokey smell was sweet and mild and the containers were big, I would use it. If the smell was unpleasantly strong and acrid, like a "closed in" fire, I would reburn it and finish it properly.

Hope someone else can chime in here.

Douglas Alpenstock wrote:In containers? I honestly can't give you a definitive answer. Especially not from afar.

Me? If the smokey smell was sweet and mild and the containers were big, I would use it. If the smell was unpleasantly strong and acrid, like a "closed in" fire, I would reburn it and finish it properly.

Hope someone else can chime in here.

Thanks again,
The smell is dreadful, and because it’s damp with urine, it would be hard to dry out to re-burn.
I guess this is one of those live and learn experiences.
Here’s a pic.
The large bucket is the problematic batch.

If I recall, a lot of the odor-producing compounds are acidic. Adding ashes to the mix might neutralize them better than urine will.

Ellendra Nauriel wrote:If I recall, a lot of the odor-producing compounds are acidic. Adding ashes to the mix might neutralize them better than urine will.

Thank you for that.
I’ll look into it.

Ellendra Nauriel wrote:If I recall, a lot of the odor-producing compounds are acidic. Adding ashes to the mix might neutralize them better than urine will.

But will it only mask the smells, or remove the harmfulness?

Dave Rennie wrote:

Ellendra Nauriel wrote:If I recall, a lot of the odor-producing compounds are acidic. Adding ashes to the mix might neutralize them better than urine will.

But will it only mask the smells, or remove the harmfulness?

I have no idea. I suspect it will convert the compounds into forms that are more water-soluble, so they wash out and are diluted easily. I don't know if the reaction converts them into less harmful compounds. It's been a long time since I tried to do chemical calculations like that.

Ellendra Nauriel wrote:

Dave Rennie wrote:

Ellendra Nauriel wrote:If I recall, a lot of the odor-producing compounds are acidic. Adding ashes to the mix might neutralize them better than urine will.

But will it only mask the smells, or remove the harmfulness?

I have no idea. I suspect it will convert the compounds into forms that are more water-soluble, so they wash out and are diluted easily. I don't know if the reaction converts them into less harmful compounds. It's been a long time since I tried to do chemical calculations like that.

Thank you.
I’ll see what I can find out.

If this was a garden patch, I would sprinkle it thinly without hesitation. The only potential concern, I guess, is too much concentration in plant pots.

I still can't find any information about the potential harm to plants (if any). It may be that the tars primarily reduce the effectiveness of inoculation, since they clog up the pores somewhat.

Just because the char is somewhat less effective in the short term doesn't mean it's going to kill plants or contaminate the soil. I guess it all depends on your risk tolerance.

Douglas Alpenstock wrote:If this was a garden patch, I would sprinkle it thinly without hesitation. The only potential concern, I guess, is too much concentration in plant pots.

I still can't find any information about the potential harm to plants (if any). It may be that the tars primarily reduce the effectiveness of inoculation, since they clog up the pores somewhat.

Just because the char is somewhat less effective in the short term doesn't mean it's going to kill plants or contaminate the soil. I guess it all depends on your risk tolerance.

Thanks.
I’d rather dump it and make more than risk harming my crop of chillies.
There’s probably 3 batches in total in that big black bucket.
It’s a lot to waste, and I really wish I’d just re-cooked that smelly batch rather than mix it in with the rest.
Live and learn hey.

I'm not wise enough to be able to discern if something is good or bad, for plants or soil, based on something as fickle as my sense of smell.

Dave Rennie wrote:Thanks.
I’d rather dump it and make more than risk harming my crop of chillies.
There’s probably 3 batches in total in that big black bucket.
It’s a lot to waste, and I really wish I’d just re-cooked that smelly batch rather than mix it in with the rest.

So you've already diluted it by 2/3? Speaking for myself, I would dilute it further and use it. But it's your call of course.

Would you consider doing us all a favour by experimenting with one pot and one plant, just to see if there are any negative effects?

Douglas Alpenstock wrote:

Dave Rennie wrote:Thanks.
I’d rather dump it and make more than risk harming my crop of chillies.
There’s probably 3 batches in total in that big black bucket.
It’s a lot to waste, and I really wish I’d just re-cooked that smelly batch rather than mix it in with the rest.

So you've already diluted it by 2/3? Speaking for myself, I would dilute it further and use it. But it's your call of course.

Would you consider doing us all a favour by experimenting with one pot and one plant, just to see if there are any negative effects?

Yes the smelly batch was added to a bucket with about 3 other batches of a similar size.
Also, most of the smelly batch had cooked properly, and only some of it was dark brown and not fully carbonised, but the stench is overpowering.
The garage stinks of it.

I’ve got several weeks until I planned on mixing it into compost and buckets, so I’ll wait and see if anyone has a concrete answer or fix.
I will try mixing ash, and I will do an experiment using it if I decide not to use it all.

I would make a pile in an unused part of my yard and let it sit there for a year or two.  Then I would use it.  Nature will fix this if you give it a little time.

Trace Oswald wrote:I would make a pile in an unused part of my yard and let it sit there for a year or two.  Then I would use it.  Nature will fix this if you give it a little time.

Thank you.
I’ve continued to inoculate it with more urine, and have turned/mixed it several times per day.
The smell seems to be reducing slightly.
I sifted out the bigger chunks as they seemed to be the wood that had not fully carbonised.
I’m going to add some compost to it in a week or two to further inoculate and try and neutralize the odour.
I’m going to add some wood ash when I can, and I think I’ll use it this year.
I’ll keep it separate from the other bicochar, in different pots so I can see if there’s a difference, and potentially only jeopardize half of my crop.
Unless someone with previous experience comes along and says DON’T DO IT!
Thanks for all the advise I’ve received!

UPDATE.
I mixed in some loam at 1:1 2 days ago to try and neutralize the smell. It worked a treat, and now smells of forest floor!
Thanks to everyone who offered suggestions.
I’m going to do one more large batch of pinecones, and then I’m done for the year!