size of biochar for various aplications ?


Ross Hunt
 

I have been using water and wood chipper to crush biochar. Most of it comes out as dust size (slurry of dust size particles)
Is there any data from studies on best crushed size biochar for types of soils for fertility and life for sequestering purpose ?
I read on a facebook posting that biochar dust in sandy soils will wash away into groundwater.
Also, might dust not have the benificial micro pores ?
Ross


Didi Meier <didimeier61@...>
 

My own research shows me 1-3mm is optional, maximum 6mm, over that it seams not to have all the pores open and available for the microbes.
That’s my research with my Biochar, produced in a closed system with high heat and hard wood off cuts.

Didi
Enviro innovations


Stephen Joseph
 

It depends on what you are trying to achieve.  if you want faster seed germination and early plant growth  response or you want to change root membrane potential to reduce the energy required to take up nutrients or you want faster movement through the soil then  less than 100 microns is preferred.  Also for application as an animal feed the report is fine biochar mixed with  feed supplement gives a great positive response at low application rates

Regards
Stephen

On Fri, May 7, 2021 at 12:22 PM Didi Meier <didimeier61@...> wrote:
My own research shows me 1-3mm is optional, maximum 6mm, over that it seams not to have all the pores open and available for the microbes.
That’s my research with my Biochar, produced in a closed system with high heat and hard wood off cuts.

Didi
Enviro innovations






d.michael.shafer@gmail.com
 

A paper presented on the Green Webinar a few months ago suggested that very small "dust" sized particles are actually hydro phobic.

M


On Fri, May 7, 2021, 6:36 AM Ross Hunt <rossahunt@...> wrote:
I have been using water and wood chipper to crush biochar. Most of it comes out as dust size (slurry of dust size particles)
Is there any data from studies on best crushed size biochar for types of soils for fertility and life for sequestering purpose ?
I read on a facebook posting that biochar dust in sandy soils will wash away into groundwater.
Also, might dust not have the benificial micro pores ?
Ross


alaa alamiri
 

Dear all,

The links below are my papers, I think, they will help you to decide about better biochar size.






with best compliments

ALAA HASAN FAHMI
Bsc. Soil&water Sciences.
MSc. Soil Chemistry and organic matter
Ph.D. Environmental Soil Chemistry
Universiti Putra Malaysia - UPM
Working at : University of Diyala





On Friday, May 7, 2021, 02:36:42 AM GMT+3, Ross Hunt <rossahunt@...> wrote:


I have been using water and wood chipper to crush biochar. Most of it comes out as dust size (slurry of dust size particles)
Is there any data from studies on best crushed size biochar for types of soils for fertility and life for sequestering purpose ?
I read on a facebook posting that biochar dust in sandy soils will wash away into groundwater.
Also, might dust not have the benificial micro pores ?
Ross


Nando Breiter
 

Ross,

Some years ago I tried a small experiment at the urging of Nikolaus Foidl. Ingredients, more or less, I don't remember precisely. Stephan Joseph might correct the ratios:

8 parts powdered biochar
1 part powdered clay
1 part powdered dolomite

Mix the powders together and add water. The powdered biochar and clay have negatively charged surfaces, while the dolomite is a double plus cation, so it acts as a so-called cation bridge. So these particles form mini-aggregates, and aggregates are what hold water in soil. The mixture I made held a lot of water and seemed to be very similar to a rich, black soil. Cation bridging between clay particles and particles of organic carbon is a known feature of fertile soil and is believed to contribute to the stabilization of organic carbon. https://www.jstor.org/stable/1468629?seq=1

Cation bridging is found in Terra Preta soils. While the char particles in TP have a large size range, the greatest percentage of them are around 20 microns in size, nearly all are bound to clay particles via a calcium ++ bridge. For reference, a human hair is about 80 microns thick.  Once a powdered biochar particle is bound to a soil aggregate, it will almost certainly stay put.

One advantage to powdering biochar is that it significantly increases the surface area exposed to the freely circulating soil solution. Here's a table that shows the quantity of particles and the total exposed surface area of a biochar particle that starts off as a 1 cm cube and is then reduced by half in size, one step at a time, to 10 microns. I calculated assuming a cube, which of course is not realistic, but the results are illustrative.

Size Quantity Total Surface Area cm2
1 cm 1 6
5 mm 8 12
2.5 mm 64 24
1.25 mm 512 48
625 μm 4,096 96
312 μm 32,768 192
156 μm 262,144 384
78 μm 2,097,152 768
39 μm 16,777,216 1536
20 μm 134,217,728 3072
10 μm 1,073,741,824 6144

Larger particles of char that have a developed internal pore structure may sorb mineral nutrients, but it does not seem to me that these nutrients are freely available to plants. Experimentation has shown that soil bacteria do not survive very deep in a char pore (depending on the paper, something in the range of 80 microns). These bacteria will of course depend on the nutrients, particularly dissolved organic matter, available in the soil solution. If bacteria can't get the nutrients they need deep in a char pore (80 microns isn't that deep), how is a plant root (reliably) supposed to do so?

Another advantage to powdering biochar is that the particles are then much more widely distributed throughout the soil.

Powdered biochar should not be surface applied alone, of course. It will wash away. And if it is mixed with pure sand as a substrate it might leech out. I don't know, I've never tried it. No practical reason to do so. 

Downsides to powdering biochar might be that it is relatively difficult to do if you don't have a proper mill. The material is more difficult to handle on its own. But in most circumstances, I don't think powdered biochar should be applied on its own.

Soil fertility is the result of a number of factors working together in concert. As such, I tend to think of biochar as a form of organic carbon that is produced by thermal rather than biological decomposition. Organic carbon is one instrument in the orchestra. The bits of stabilized organic carbon in soils of biological origin that are the backbone of soil fertility are very small.

Comments and criticism welcome.

Kind regards,

Nando






CarbonZero
+41 76 303 4477 cell / WhatsApp / Signal (https://signal.org/)


On Fri, May 7, 2021 at 10:12 AM d.michael.shafer@... <d.michael.shafer@...> wrote:
A paper presented on the Green Webinar a few months ago suggested that very small "dust" sized particles are actually hydro phobic.

M


On Fri, May 7, 2021, 6:36 AM Ross Hunt <rossahunt@...> wrote:
I have been using water and wood chipper to crush biochar. Most of it comes out as dust size (slurry of dust size particles)
Is there any data from studies on best crushed size biochar for types of soils for fertility and life for sequestering purpose ?
I read on a facebook posting that biochar dust in sandy soils will wash away into groundwater.
Also, might dust not have the benificial micro pores ?
Ross


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Stephen Joseph
 

Hi Nando

What type of clay did you use?  

Smectite gives you the highest CEC and Kaolin the highest AEC (as a general rule) depending on the substituted elements in the clay lattice structure and thermal/chemical treatment.

Normally we add a little more total minerals (30%) to 70% fine biochar.  In fact we did an experiment in Tibet and the greatest pasture response was 50% 50% attapulgite clay : yak dung biochar mixture.  This has been published.

Regards
Stephen


On Fri, May 7, 2021 at 8:26 PM Nando Breiter <nando@...> wrote:
Ross,

Some years ago I tried a small experiment at the urging of Nikolaus Foidl. Ingredients, more or less, I don't remember precisely. Stephan Joseph might correct the ratios:

8 parts powdered biochar
1 part powdered clay
1 part powdered dolomite

Mix the powders together and add water. The powdered biochar and clay have negatively charged surfaces, while the dolomite is a double plus cation, so it acts as a so-called cation bridge. So these particles form mini-aggregates, and aggregates are what hold water in soil. The mixture I made held a lot of water and seemed to be very similar to a rich, black soil. Cation bridging between clay particles and particles of organic carbon is a known feature of fertile soil and is believed to contribute to the stabilization of organic carbon. https://www.jstor.org/stable/1468629?seq=1

Cation bridging is found in Terra Preta soils. While the char particles in TP have a large size range, the greatest percentage of them are around 20 microns in size, nearly all are bound to clay particles via a calcium ++ bridge. For reference, a human hair is about 80 microns thick.  Once a powdered biochar particle is bound to a soil aggregate, it will almost certainly stay put.

One advantage to powdering biochar is that it significantly increases the surface area exposed to the freely circulating soil solution. Here's a table that shows the quantity of particles and the total exposed surface area of a biochar particle that starts off as a 1 cm cube and is then reduced by half in size, one step at a time, to 10 microns. I calculated assuming a cube, which of course is not realistic, but the results are illustrative.

Size Quantity Total Surface Area cm2
1 cm 1 6
5 mm 8 12
2.5 mm 64 24
1.25 mm 512 48
625 μm 4,096 96
312 μm 32,768 192
156 μm 262,144 384
78 μm 2,097,152 768
39 μm 16,777,216 1536
20 μm 134,217,728 3072
10 μm 1,073,741,824 6144

Larger particles of char that have a developed internal pore structure may sorb mineral nutrients, but it does not seem to me that these nutrients are freely available to plants. Experimentation has shown that soil bacteria do not survive very deep in a char pore (depending on the paper, something in the range of 80 microns). These bacteria will of course depend on the nutrients, particularly dissolved organic matter, available in the soil solution. If bacteria can't get the nutrients they need deep in a char pore (80 microns isn't that deep), how is a plant root (reliably) supposed to do so?

Another advantage to powdering biochar is that the particles are then much more widely distributed throughout the soil.

Powdered biochar should not be surface applied alone, of course. It will wash away. And if it is mixed with pure sand as a substrate it might leech out. I don't know, I've never tried it. No practical reason to do so. 

Downsides to powdering biochar might be that it is relatively difficult to do if you don't have a proper mill. The material is more difficult to handle on its own. But in most circumstances, I don't think powdered biochar should be applied on its own.

Soil fertility is the result of a number of factors working together in concert. As such, I tend to think of biochar as a form of organic carbon that is produced by thermal rather than biological decomposition. Organic carbon is one instrument in the orchestra. The bits of stabilized organic carbon in soils of biological origin that are the backbone of soil fertility are very small.

Comments and criticism welcome.

Kind regards,

Nando






CarbonZero
+41 76 303 4477 cell / WhatsApp / Signal (https://signal.org/)


On Fri, May 7, 2021 at 10:12 AM d.michael.shafer@... <d.michael.shafer@...> wrote:
A paper presented on the Green Webinar a few months ago suggested that very small "dust" sized particles are actually hydro phobic.

M


On Fri, May 7, 2021, 6:36 AM Ross Hunt <rossahunt@...> wrote:
I have been using water and wood chipper to crush biochar. Most of it comes out as dust size (slurry of dust size particles)
Is there any data from studies on best crushed size biochar for types of soils for fertility and life for sequestering purpose ?
I read on a facebook posting that biochar dust in sandy soils will wash away into groundwater.
Also, might dust not have the benificial micro pores ?
Ross


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


mikethewormguy
 

We like to use 1/4 inch minus wood biochar for soil applications and powder char, the finer the better, for liquid applications.

We have used bigger pieces (1/2 - 1 inch) of wood char produced from our fire pit char process in our garden soil.  We did this just because.


Tom Miles
 

Do fine particle have the same effect if they are granulated for convenience of handling and safety of application? There is clearly an additional cost for granulation.

 

Tom

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of mikethewormguy via groups.io
Sent: Friday, May 07, 2021 5:42 AM
To: main@Biochar.groups.io
Subject: Re: [Biochar] size of biochar for various aplications ?

 

We like to use 1/4 inch minus wood biochar for soil applications and powder char, the finer the better, for liquid applications.

We have used bigger pieces (1/2 - 1 inch) of wood char produced from our fire pit char process in our garden soil.  We did this just because.


Nando Breiter
 

Hi Stephen,

I used smectite.

Interesting paper. Thanks for sharing it.

n

CarbonZero
+41 76 303 4477 cell / WhatsApp / Signal (https://signal.org/)


On Fri, May 7, 2021 at 1:12 PM Stephen Joseph <joey.stephen@...> wrote:
Hi Nando

What type of clay did you use?  

Smectite gives you the highest CEC and Kaolin the highest AEC (as a general rule) depending on the substituted elements in the clay lattice structure and thermal/chemical treatment.

Normally we add a little more total minerals (30%) to 70% fine biochar.  In fact we did an experiment in Tibet and the greatest pasture response was 50% 50% attapulgite clay : yak dung biochar mixture.  This has been published.

Regards
Stephen


On Fri, May 7, 2021 at 8:26 PM Nando Breiter <nando@...> wrote:
Ross,

Some years ago I tried a small experiment at the urging of Nikolaus Foidl. Ingredients, more or less, I don't remember precisely. Stephan Joseph might correct the ratios:

8 parts powdered biochar
1 part powdered clay
1 part powdered dolomite

Mix the powders together and add water. The powdered biochar and clay have negatively charged surfaces, while the dolomite is a double plus cation, so it acts as a so-called cation bridge. So these particles form mini-aggregates, and aggregates are what hold water in soil. The mixture I made held a lot of water and seemed to be very similar to a rich, black soil. Cation bridging between clay particles and particles of organic carbon is a known feature of fertile soil and is believed to contribute to the stabilization of organic carbon. https://www.jstor.org/stable/1468629?seq=1

Cation bridging is found in Terra Preta soils. While the char particles in TP have a large size range, the greatest percentage of them are around 20 microns in size, nearly all are bound to clay particles via a calcium ++ bridge. For reference, a human hair is about 80 microns thick.  Once a powdered biochar particle is bound to a soil aggregate, it will almost certainly stay put.

One advantage to powdering biochar is that it significantly increases the surface area exposed to the freely circulating soil solution. Here's a table that shows the quantity of particles and the total exposed surface area of a biochar particle that starts off as a 1 cm cube and is then reduced by half in size, one step at a time, to 10 microns. I calculated assuming a cube, which of course is not realistic, but the results are illustrative.

Size Quantity Total Surface Area cm2
1 cm 1 6
5 mm 8 12
2.5 mm 64 24
1.25 mm 512 48
625 μm 4,096 96
312 μm 32,768 192
156 μm 262,144 384
78 μm 2,097,152 768
39 μm 16,777,216 1536
20 μm 134,217,728 3072
10 μm 1,073,741,824 6144

Larger particles of char that have a developed internal pore structure may sorb mineral nutrients, but it does not seem to me that these nutrients are freely available to plants. Experimentation has shown that soil bacteria do not survive very deep in a char pore (depending on the paper, something in the range of 80 microns). These bacteria will of course depend on the nutrients, particularly dissolved organic matter, available in the soil solution. If bacteria can't get the nutrients they need deep in a char pore (80 microns isn't that deep), how is a plant root (reliably) supposed to do so?

Another advantage to powdering biochar is that the particles are then much more widely distributed throughout the soil.

Powdered biochar should not be surface applied alone, of course. It will wash away. And if it is mixed with pure sand as a substrate it might leech out. I don't know, I've never tried it. No practical reason to do so. 

Downsides to powdering biochar might be that it is relatively difficult to do if you don't have a proper mill. The material is more difficult to handle on its own. But in most circumstances, I don't think powdered biochar should be applied on its own.

Soil fertility is the result of a number of factors working together in concert. As such, I tend to think of biochar as a form of organic carbon that is produced by thermal rather than biological decomposition. Organic carbon is one instrument in the orchestra. The bits of stabilized organic carbon in soils of biological origin that are the backbone of soil fertility are very small.

Comments and criticism welcome.

Kind regards,

Nando






CarbonZero
+41 76 303 4477 cell / WhatsApp / Signal (https://signal.org/)


On Fri, May 7, 2021 at 10:12 AM d.michael.shafer@... <d.michael.shafer@...> wrote:
A paper presented on the Green Webinar a few months ago suggested that very small "dust" sized particles are actually hydro phobic.

M


On Fri, May 7, 2021, 6:36 AM Ross Hunt <rossahunt@...> wrote:
I have been using water and wood chipper to crush biochar. Most of it comes out as dust size (slurry of dust size particles)
Is there any data from studies on best crushed size biochar for types of soils for fertility and life for sequestering purpose ?
I read on a facebook posting that biochar dust in sandy soils will wash away into groundwater.
Also, might dust not have the benificial micro pores ?
Ross


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


mikethewormguy
 

Tom,

We get our fine powder typically from screening some of the 1/4 inch minus char..

One does not need alot of fine char powder to make black water.

Some of the answer regarding granulation will depend on what binder is used in the agglomeration process, as well as, how well and how long it take the granule to fall apart in water..

my 2 cents

Mike







Sent from my Verizon, Samsung Galaxy smartphone


Norm Baker
 

Stephen;

I have been making and using biochar in an experimental garden for about 12 years and am convinced it does not need to be ground or micronized except when one wants to put it through some sort of machinery for soil incorporation. In my experience, almost all of the biochar is broken up, with no easily seen large particles within one year. My question is how much of a faster response do you get for seed germination and early plant growth, or how much does it change the root membrane potential to reduce the energy required to take up nutrients?

Norm


Norm Baker
 

Nando;

Those exposed surface areas seem to be just the external surface area. Those make sense. But, in a soil, exposed to a water soil solution, the transport of cations and anions is at the molecular level - in and out of pores and their internal surface area. Yes, the formation of carboxyl groups on the surface of biochar is assumed to be at the surface. Does anyone agree or disagree with this statement? In other words, I find it plausible to believe carboxyl groups are formed within the whole, but probably not all, of a biochar particle.

I find it more relevant to think of biochar as existing in a soil solution exposed to all of the ions available.

Feel free to disagree.

Norm


Nando Breiter
 

Norm,

The numbers I gave were just illustrative, as I wrote. It makes sense to me that a portion of a pore would be exposed to the circulating soil solution, and I used the research on how deep bacteria survive in char pores as a proxy of how deep the soil solution might freely circulate. You wrote "the transport of cations and anions is at the molecular level - in and out of pores and their internal surface area". My question is how free is that in and out, particularly the out.

Do char pores in soil remain open, or do they fill with debris?
Are there forces that circulate soil solution in and out of the pores? Or do the pores become filled as the char particle hydrates and circulation tends to stagnate?

To obtain nutrients bound to organic carbon and clays, plant roots will release H+ cations to the soil solution. How easily does H+ circulate into relatively deep char pores, are exchanged with nutrient cations, and those nutrient cations circulate back out of the pore to be absorbed by the plant? I'm sure it can happen. It just seems to me that the focus on the vast internal surface area of biochar pores is an exaggeration, and that cation exchange will occur much more easily on the outer, exposed surfaces of a char particle, which may include the entrance to a pore, but the deeper the pore, the less likely it seems cation exchange might occur.

There is a common theme expressed that freshly produced biochar can sorb nutrients in a way that depletes plant availability, "so make sure to charge your biochar before adding it to soil". Why would biochar in particular behave like this when clays and other types of organic carbon do not? Are nutrients in soil solution being sorbed into pores and getting trapped in there because the H+ cations plant roots release cannot reach them?

If the char particle is small enough, say 100 microns or so, H+ cations will be able to more easily circulate into the entrance of a pore, exchange with a plant nutrient cation sorbed at a negatively charged site, and that cation circulate out of the pore to be absorbed. In this case, a much greater percentage of the internal pore structure of that small particle would be easily available for cation exchange compared to one that is significantly larger.


CarbonZero
+41 76 303 4477 cell / WhatsApp / Signal (https://signal.org/)


On Fri, May 7, 2021 at 10:34 PM Norm Baker <ntbakerphd@...> wrote:
Nando;

Those exposed surface areas seem to be just the external surface area. Those make sense. But, in a soil, exposed to a water soil solution, the transport of cations and anions is at the molecular level - in and out of pores and their internal surface area. Yes, the formation of carboxyl groups on the surface of biochar is assumed to be at the surface. Does anyone agree or disagree with this statement? In other words, I find it plausible to believe carboxyl groups are formed within the whole, but probably not all, of a biochar particle.

I find it more relevant to think of biochar as existing in a soil solution exposed to all of the ions available.

Feel free to disagree.

Norm


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Ron Larson
 

List, cc Nado and Norm (I’ve known both for a long time aand impressed by both - ss for almost all before me.on this impressive and important thread.  
I acknowledge the many other thread contributors. 

1.  This coming since this is one of this list’s fastest moving and best threads ever.  Thanks to Nando for starting this - with just one cite.

2.  The 1988 Oades article is available non-fee at 

It clearly is first rate.

3.   I checked Google Scholar on number of cites in 2021.  So far (1/4 year) over 900.   Possibly heading for 3000

4.  I thought this is a wonderful tribute to biochar.  But (not counting, it seemed only maybe 1/4 or 1/5 of the papers were biochar oriented)

5.  So I checked also for. 2007 (Biochar's first official year) - and found almost 1000 Oades cites.(probably not more than one or two cites using the word “biochar"). 

So the topic is a faster growth area for biochar than other soil areas.  Both growth rates would be good to know.

6.  So I hope someone can carry this biochar literature growth question further. (And others). 
I’m going to continue working only on non-size, non-soil biochar issues - with thanks to those in those two specific biochar areas

7.  I recommend Nando’s web cite - given below.

8.  I hope someone with the Musk X-Prize group is reading thist.  This is only one of several biochar-CDR areas full of important difficult science - deserving of $100 million.

Ron



On May 7, 2021, at 3:58 PM, Nando Breiter <nando@...> wrote:

Norm,

The numbers I gave were just illustrative, as I wrote. It makes sense to me that a portion of a pore would be exposed to the circulating soil solution, and I used the research on how deep bacteria survive in char pores as a proxy of how deep the soil solution might freely circulate. You wrote "the transport of cations and anions is at the molecular level - in and out of pores and their internal surface area". My question is how free is that in and out, particularly the out.

Do char pores in soil remain open, or do they fill with debris?
Are there forces that circulate soil solution in and out of the pores? Or do the pores become filled as the char particle hydrates and circulation tends to stagnate?

To obtain nutrients bound to organic carbon and clays, plant roots will release H+ cations to the soil solution. How easily does H+ circulate into relatively deep char pores, are exchanged with nutrient cations, and those nutrient cations circulate back out of the pore to be absorbed by the plant? I'm sure it can happen. It just seems to me that the focus on the vast internal surface area of biochar pores is an exaggeration, and that cation exchange will occur much more easily on the outer, exposed surfaces of a char particle, which may include the entrance to a pore, but the deeper the pore, the less likely it seems cation exchange might occur.

There is a common theme expressed that freshly produced biochar can sorb nutrients in a way that depletes plant availability, "so make sure to charge your biochar before adding it to soil". Why would biochar in particular behave like this when clays and other types of organic carbon do not? Are nutrients in soil solution being sorbed into pores and getting trapped in there because the H+ cations plant roots release cannot reach them?

If the char particle is small enough, say 100 microns or so, H+ cations will be able to more easily circulate into the entrance of a pore, exchange with a plant nutrient cation sorbed at a negatively charged site, and that cation circulate out of the pore to be absorbed. In this case, a much greater percentage of the internal pore structure of that small particle would be easily available for cation exchange compared to one that is significantly larger.


CarbonZero
+41 76 303 4477 cell / WhatsApp / Signal (https://signal.org/)


On Fri, May 7, 2021 at 10:34 PM Norm Baker <ntbakerphd@...> wrote:
Nando;

Those exposed surface areas seem to be just the external surface area. Those make sense. But, in a soil, exposed to a water soil solution, the transport of cations and anions is at the molecular level - in and out of pores and their internal surface area. Yes, the formation of carboxyl groups on the surface of biochar is assumed to be at the surface. Does anyone agree or disagree with this statement? In other words, I find it plausible to believe carboxyl groups are formed within the whole, but probably not all, of a biochar particle.

I find it more relevant to think of biochar as existing in a soil solution exposed to all of the ions available.

Feel free to disagree.

Norm



--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Stephen Joseph
 

Norm

The carboxyl groups come mainly from a thin layer of organics that are exuded by the roots and microbes and from other soil organic matter.

 As soon as you put biochar into the soil is adsorbs functionalised organic molecules


Its a free article

After a while organomineral clusters form on the surface and these have a high concentration of functional groups.  read this paper.


I must have mentioned this many times that the carbon matrix on the surface of biochar is hard to oxidise unless it is made at  low temperatures where you have a high concentration of labile organic compounds on the surface.

Regards
Stephen

On Sat, May 8, 2021 at 6:34 AM Norm Baker <ntbakerphd@...> wrote:
Nando;

Those exposed surface areas seem to be just the external surface area. Those make sense. But, in a soil, exposed to a water soil solution, the transport of cations and anions is at the molecular level - in and out of pores and their internal surface area. Yes, the formation of carboxyl groups on the surface of biochar is assumed to be at the surface. Does anyone agree or disagree with this statement? In other words, I find it plausible to believe carboxyl groups are formed within the whole, but probably not all, of a biochar particle.

I find it more relevant to think of biochar as existing in a soil solution exposed to all of the ions available.

Feel free to disagree.

Norm


Stephen Joseph
 

Hi Norm

Not a lot of carefully run experiments in this space ( type into Google scholar "biochar particle size + plant response") and there are some interesting studies.  My experience is larger particles for soil structure and other physical properties.  Small particles for fast plant and seed response but I often use both large particles and very fine particles that have been processed by worms or through grinding.  Seems to have a greater benefit than one size alone.  My last experiment were to put 5mm long  by 2mm wide  wood biochar  soaked in wood vinegar around my plants to deter the slugs and snails.

Regards
Stephen

On Sat, May 8, 2021 at 6:24 AM Norm Baker <ntbakerphd@...> wrote:
Stephen;

I have been making and using biochar in an experimental garden for about 12 years and am convinced it does not need to be ground or micronized except when one wants to put it through some sort of machinery for soil incorporation. In my experience, almost all of the biochar is broken up, with no easily seen large particles within one year. My question is how much of a faster response do you get for seed germination and early plant growth, or how much does it change the root membrane potential to reduce the energy required to take up nutrients?

Norm


mikethewormguy
 

Stephen,

A Garlic soaked char ring around plants also works for slugs&snails as a deterrent line.

We only fine char for the worms along with fine ground green sand.  Green sand is a soft mineral that grinds easily.

my 2 cents

Mike


Ross Hunt
 

Thanks for ll the replys to my question about size.
I will continue using wood chipper to make dust( slurry including urine) then into hot compost. 
Finding clay to add to my sandy soil and biochar is something I will be looking into.
I am not sure that the dust will bind to sandy soil enough that it will not wash away. I GUESS the fine dust that needs replacing is probably worth the benifits of having exponentially more surface area.

On Fri, 7 May 2021, 12:57 mikethewormguy via groups.io, <mikethewormguy=aol.com@groups.io> wrote:
Tom,

We get our fine powder typically from screening some of the 1/4 inch minus char..

One does not need alot of fine char powder to make black water.

Some of the answer regarding granulation will depend on what binder is used in the agglomeration process, as well as, how well and how long it take the granule to fall apart in water..

my 2 cents

Mike







Sent from my Verizon, Samsung Galaxy smartphone


Stephen Joseph
 

depends if they are dispersable once in the ground.


On Sat, May 8, 2021 at 2:44 AM Tom Miles <tmiles@...> wrote:

Do fine particle have the same effect if they are granulated for convenience of handling and safety of application? There is clearly an additional cost for granulation.

 

Tom

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of mikethewormguy via groups.io
Sent: Friday, May 07, 2021 5:42 AM
To: main@Biochar.groups.io
Subject: Re: [Biochar] size of biochar for various aplications ?

 

We like to use 1/4 inch minus wood biochar for soil applications and powder char, the finer the better, for liquid applications.

We have used bigger pieces (1/2 - 1 inch) of wood char produced from our fire pit char process in our garden soil.  We did this just because.