How much is too much Bio-Char in a potting mix?

[JakeFruit]

I found Big Earth Supply was selling the stuff, so I bought a few bags. Mixed the bio-char in at what I guess was a 20% ratio and used the mix when I re-potted 4 mangoes. The smallest mango went south immediately and died 2 days ago; it looked more shriveled and dehydrated each day (despite watering), but it also had lost a fair amount of roots in the transplanting. Biggest mango has yet to show any signs of being phased by the new mixture, looks healthy and might just be pushing new growth. Another has lost a few leaves and looks a little sad, but nothing like the smallest one.

Can too much Bio-Char cause issues like what occurred? I'm thinking it's just my ham-handed re-potting, but I'm worried it's more than just that. The big mango is my year old Sweet Tart graft, I'd hate to lose that one.

[Finca La Isla]

I think that true, good quality, biochar should be a pretty inert amendment to potting soil.  If the char was actually produced at a low temperature and has lots of strange volatiles or they used old wood with chemicals.....
The amount could depend also on the other ingredients in your medium.  Is it sandy, lots of clay? etc.
We employ biochar that we make ourselves at a high temperature,(850C degrees).  It’s soaked with microorganisms, worm tea, humic acid, stuff like that.
I’m curious why you wouldn’t just plant out your 1 year old mango tree?
Peter

[JakeFruit]

Thanks for the input Peter. The potting mix is more or less this:

40% - Pine Bark
20% - Coco Coir
15% - Bio Char
10% - Pool Filter Sand
5% - Perlite
5% - Vermiculite
5% - Earthworm castings

As to putting it in the ground, I plan to eventually, but there's a lot of development to come on my lot. I'm not sure exactly where I want it to go just yet.

[Pnguyen]

Gary from Laguna Hills Nursery said the plant might be in shock and shed leafs to conserve their resources after transplant.  They could come back with new leafs in few weeks.

[Pnguyen]

If you have time, Gary Youtube of Laguna Hills Nursery.  He discussed in detail about soils.  He also has one on re-potting.  I am following his guides on all of my potting plants last weekend.  I am hopping that he is correct.  I also transplanted 2 avocado and 1 Antamoya to the raise bed with sandy soil mix the week before.  They seem to be OK.  I avoid mixing all wood compost, potting mix and mulch.  I have sand, coco coir and/or peat moss, perlite and little manure and/or organic compost.  After a week and a half, they all seem OK.  For potting soil, I add very little fine charcoal fine.  As I recalled, Gary said he only have 5% of charcoal to his potting mix and that is more than plenty. 

 https://www.youtube.com/watch?v=KHZHy3_7PPE

I am hopping this help.  I have many plant die on me in sudden dead so I am learning from others and do trials and errors.

[Finca La Isla]

That’s a very light medium.  What is the soil like where you are eventually going to plant?  At my place we have a natural soil that I call clay loam.  Consequently, I like to have significant clay in my potting medium.  That way there is less trauma for the tree when it goes into the ground.  Is your eventual soil anything like your potting medium?
Peter

[Pnguyen]

I am no expert so please take my thought like a grain of sand.  I highly recommend that you view Gary video because he explain them scientifically and very clearer.  From my understanding, plant strive from mineral in which sand is minerals. They also need water and oxygen for root systems. Nutrients also are essential. In nature they are from decaying leafs of their own-Nature way of recycling.  We can add light fertilizer and mix into the top of the soil. Water will carrying them to the root system.  Sand and perlite help water to drain fast but also allow oxygen, from fresh water and atmosphere, to get to the system.

Gary said most plants died after 2-3 years because of the potting soil from most nurseries.  Potting Soils are cheap and easy because mostly make up of wood waste.  Wood will decomposed over time, compacted, consumed oxygen and rot.  They then become toxic to the plantS with no nutrient value.  They also hold water that rotten the roots.

Good nursery mixed more sand into their potting soil, peat moss and perlite so the root systems can breath and absorbed water that they need.  Any over watering is not an issue because sandy soil won’t hold water Log to rot the roots. However, peat moss and perlite are costly.  Sand is too heavy by itself for transport.

For clay which is the same for my area, Gary recommend to dig 18 to 24” deep and mixing 50% sand to the clay and plant on the mount is much better.  I am too lazy to dig so I have 18” planter with mount of 6” to make it about 24” above grade.  Expert said most plant root systems are 6”-12” into the soil because I they need to be closed to the surface to breath.  That is enough to avoid stagnant water from slow draining clay soil.

It is make scientific sense to me. In the past, my persimmon suddenly die on me or other plats die after heavy rain.  By last few year all doing good in raise bed with sandy soil.  I now wash off all potting soil from large retailer and repot or transplant to soil with mix of sand, coco coir or peat moss and perlite with some organic ferterlizer. I just provide mulch to retain moisture and mix fertilizer at the surfaces over time

I visited wineries and vineyards.  I noticed all grape vines are on sandie soils. They must know something.  Maybe Big retail nursery have different businesses models which is selling lots of plant every seasons.

[pineislander]

  It’s soaked with microorganisms, worm tea, humic acid, stuff like that.

Peter

At 20 % in the mix the problem could be that you used it "raw". Charcoal is an adsorber, it takes and holds onto ions which would be your nutrients.

However, depending on how it was made it can also contain some ash which is high pH (>8)or tars.

Usually the biochar is conditioned two ways by adding nutrients and then life.

I soaked it in a fish emulsion and micronutrient solution for two weeks it floated for many days and you could see water bubbles being released and eventual water level dropped as the biochar became wetted.
After that I added it to a compost pile for a month to colonize it with microorganisms.
I used it in potting mix with no problems.
This post has pictures of my experience:
http://tropicalfruitforum.com/index.php?topic=31671.msg349153#msg349153

This 2 part video explains how he does it:
https://www.youtube.com/watch?v=DOEyIPVn2r0
https://www.youtube.com/watch?v=D-vlZ5u6avY

[RollingInTheWeeds]

Thanks for the input Peter. The potting mix is more or less this:

40% - Pine Bark
20% - Coco Coir
15% - Bio Char
10% - Pool Filter Sand
5% - Perlite
5% - Vermiculite
5% - Earthworm castings

When you say "pine bark", do you mean uncomposted bark from pine trees?  Personally I would advise against putting that in any potting mix (except maybe orchids).  Pine bark is only intended to be used as a mulch (i.e., put it on TOP of the ground to help prevent weeds, and to help the soil retain moisture).  But IN the soil, it will begin composting.  Essentially, as microorganisms feed on it, they will suck nitrogen from the soil in the process and will in various ways make the soil inhospitable to living roots.  It's kind of like putting uncomposted wood chips in the soil.  They start rotting.  In Nature, soil (where the roots grow) doesn't rot.  Mulch on *top* of the soil rots.

Even those bags of "potting soil" people buy in stores aren't soil that will be good for plants longterm.  Look closely at the stuff, and you'll see pieces of wood that are *mostly* composted.  The manufacturer adds nitrogen to the mix to keep the wood chips from killing the plants immediately.  After a while, the nitrogen gets used up and the wood starts composting again and the plant begins to suffer.  But by then (months or a year later), you don't realize that the stuff you were told to put your plant in is causing the problem.  The potting soil manufacturers still sell plenty of product.  Most people grow annuals in it, so it doesn't matter.  It's normal for the plants to die in a few months anyway.

Also, I wonder whether the bark has pine sap in it.  Pine sap is what turpentine comes from -- again, something that doesn't belong in the soil.

[sunny]

Thanks for the input Peter. The potting mix is more or less this:

40% - Pine Bark
20% - Coco Coir
15% - Bio Char
10% - Pool Filter Sand
5% - Perlite
5% - Vermiculite
5% - Earthworm castings

When you say "pine bark", do you mean uncomposted bark from pine trees?  Personally I would advise against putting that in any potting mix (except maybe orchids).  Pine bark is only intended to be used as a mulch (i.e., put it on TOP of the ground to help prevent weeds, and to help the soil retain moisture).  But IN the soil, it will begin composting.  Essentially, as microorganisms feed on it, they will suck nitrogen from the soil in the process and will in various ways make the soil inhospitable to living roots.  It's kind of like putting uncomposted wood chips in the soil.  They start rotting.  In Nature, soil (where the roots grow) doesn't rot.  Mulch on *top* of the soil rots.

Even those bags of "potting soil" people buy in stores aren't soil that will be good for plants longterm.  Look closely at the stuff, and you'll see pieces of wood that are *mostly* composted.  The manufacturer adds nitrogen to the mix to keep the wood chips from killing the plants immediately.  After a while, the nitrogen gets used up and the wood starts composting again and the plant begins to suffer.  But by then (months or a year later), you don't realize that the stuff you were told to put your plant in is causing the problem.  The potting soil manufacturers still sell plenty of product.  Most people grow annuals in it, so it doesn't matter.  It's normal for the plants to die in a few months anyway.

Also, I wonder whether the bark has pine sap in it.  Pine sap is what turpentine comes from -- again, something that doesn't belong in the soil.

Yes i agree, i have killed tree's by mixing pine bark into the soil...but on internet there are many éxperts' who advice to do it.

Al's gritty mix is one of them.

[SeaWalnut]

Bark has tannins ,tannic acid,like coffee and its good to make the soil acidic.It also contains more N than woodchips and its easyer to compost than wood.

[Pnguyen]

SeaWalnut and RollingintheWeed explained very well.  Bark or large wood chip might be good for a while depends on type and sizes.  Large size of bark or chip provide the porosity to the soil in short term which the roots can breath.  However, the decomposed wood chips will be a problem as eluded by Rollingintheweed.

[Finca La Isla]

I agree with most of what’s being said about chunks of bark in the medium.  But I think that there is something important to consider.  That’s the composition of the soil where the tree will eventually be planted.  The more similar the medium is to the soil the less shock the tree will have to endure when planted out.
Is there clay in the planting area?  Then clay should be a component in the medium.
Fundamentally, we’ll balanced soil is made up of clay, sand, and organic materials.  Biochar and other amendments can add to the quality but I can’t imagine a medium without clay if the soil contains clay which is almost everywhere.
Another question, what was the medium composed of that the mango tree originally came in?  If the new medium is quite different that can create trauma.
Peter

[JakeFruit]

I'm on the West Coast of Florida, maybe 1/2 of a mile from the Gulf. My lot used to be part of an orange grove, I haven't gone down too deep, but it's fairly sandy soil. I obsessed over the potting soil mix for quite awhile, the pine bark addition was after reading numerous sources recommending it. The original batch lacked bio-char and all the mangoes are doing fine, but they were all grafted trees with at least a year since they were grafted. The new batch with the bio char seems to be doing well for several trees, the Sweet Tart (the largest of them) is about to push new growth and looks like it's thriving.

Unfortunately, two of the trees that went into the new mix are now dead, but I think I know why. These were late-season grafts, each had just one flush of new growth when I transplanted them. I believe they were just too fragile to transplant, I should have waited another month or two and let them push some new spring growth. Neither had a very good root system and each lost some roots in the process.