Citric Acid and Cannabis Horticulture with Professor Matt Rize

cannakis

cannakis

Well-Known Member
Matt Rize said:
Here is the link to my blog, with many more posts. I lost all the formatting with the paste.

http://mattrize.blogspot.com/2010/10/citric-acid-and-cannabis-horticulture.html

"Citric Acid and Cannabis Horticulture:

Citric acid is a weak organic acid, it is a tricarboxylic acid, C6H8O7 . It is a natural preservative and used to make food taste sour, like 'sour patch kids' and soda. In biochemistry, citric acid is important as an intermediate in the citric acid cycle and therefore occurs in the metabolism of virtually all living things.

This post is all about citric acid.. The Cannabis growers of the world use citric acid to lower water pH for container gardens. Cannabis grown in soil-less organics prefers a soil(less) solution around 6.3 pH, and hydro is lower. A neutral water pH is 7.0, and my tap water is usually around 8.0 pH. So WHY do we use citric acid, and not the countless other acids, to lower our pH? The reasons are solid, let's investigate.
We need to begin by defining the important soil science terms that relate to soil-less organics.

Soil:
Layer of unconsolidated material found at the Earth's surface that has been influenced by the soil forming factors: climate, relief, parent material, time, and organisms. Soil normally consists of weathered mineral particles, dead and living organic matter, air space, and the soil solution.

Soil Solution:
Aqueous liquid found within a soil. This liquid normally contains ions released from mineral particles, organic matter or plant roots and leaves.

Soil Colloids:
Very small organic and inorganic particles found in a soil. Inorganic colloids are often clay particles. Soil colloids carry a negative electrical charge and are the primary sites for cation exchange. Soil colloids hold large quantities of elements and compounds which are used by plants for nutrition.

Ions:
An atom, molecule or compound that carries either a positive (cation) or negative (anion) electrical charge.

Cation Exchange Capacity:
The capacity of a soil to exchange cations with the soil solution. Often used as a measure of potential soil fertility.

Okay, now we have learned: what soil is, what a soil solution is, and how soil colloids play a key role in plant nutrition by holding elements and compounds.

BACK TO CITRIC ACID...

Citric acid is valuable as an additive in Cannabis horticulture for these reasons:

A. Citric acid (C6H8O7 ) bonds to Phosphorus anions (P-), making them soluble in the rhizosphere and soil solution.

Phosphorus anions (P-) are not easily mobile in the soil solution. The soil solution is a thin layer of water and microbes surrounding particles in media, soil-less and soil. Phosphorus anions bond with media particles, other elements, and organic matter. When bound P- is made insoluble and unavailable to plants roots. Citric acid bonds with P- and this keeps this needed nutrient in a form available to plant roots.

There are cations in the soil(less) solution. There are also cations in the cation exchange sites of media particles. Together these cations are held in equilibrium, but things can go wrong, especially in an unbalanced soil-less media. Managing this equilibrium is our goal.

By adding citric acid to our water and/or nutrient solution we release (solubilize) the Phosphorus anions. The roots can then use the ions in the soil solution and rhizosphere. The ability of roots to uptake all nutrients is directly dependent on pH of the solution, and the solubility of those nutrients. Citric acid (aka citrate) increases the bio-availability of Phosphorus anions (P-) present in the media.

B. Citric acid plays a role in the Krebs Cycle
Look for a post on this subject soon!

Look for an upcoming post on ROOT EXUDATES! Roots secrete all sorts of weak acids to free up N/P/K, Ca, Fe, and possibly other elements.

Root Exudates: (substances secreted by the roots).
Roots exude large amounts of citric acid into the grow media, this keeps the P- soluble in the rhizosphere and soil solution. This citric acid, and other acid root exudates , mineralize P- from organic matter like soft rock phosphate or bat guano.

Some good reading can be found below. Definitions were adapted from: PhysicalGeography.net.

1. Bioavailability of soil inorganic P in the rhizosphere as affected by root-induced chemical changes: a review
Philippe Hinsinger
Plant and Soil 237: 173–195, 2001.
(full text) http://www.plantstress.com/Articles/min_deficiency_m/P-bioavailability.pdf

2. Effects of root exudates on nutrient availability in the rhizosphere
A. Gransee
Plant Nutrition Developments in Plant and Soil Sciences, 2002, Volume 92, Symposium 9, 626-627,
(abstract only for now) http://www.springerlink.com/content/n216w5006k27754p/

3. Carbonic Acid Decomposition
Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois
(full text) http://www.newton.dep.anl.gov/askasci/chem99/chem99661.htm "
Click to expand...
but what would be the application? rinds too? thank you for tge grwat ibfornatin!
 
T

tsmit420

Member
jnuggs said:
Professor Matt - Appreciate your time posting this. I now am interested in further researching the use of citric acid for the benefit of my soil microbes as well. Once again, thank you, you have reopened my mind.
Click to expand...
Organic acids have many benefits and as long as your ph is good organic acids are beneficial food sources for microbes. acetic acid (vinegar) is used as a food source for microbes infact microbes can actually generate electricity using acetate via a microbial fuel cell. organic acids aslo help to chelate micro nutrients. there are many synthetic fertilizers based on organic acids like ammonium citrate, potassium citrate, calcium magnesium as well as acetates and lactates. there is a product by CANNA called Bio Boost it is a fermented plant extract(you can make these yourselves easily) these fermented plant extracts are loaded with citric, lactic, acetic acids as well as amino acids and fatty acids (all produced biologically). these help give the products a very long shelf life through there acidity, chelate and solubilize just about everything and when the acidity is neutralized ,which can happen simply by aerating it for awhile. These compounds whicht suppressed microbial populations now act as a powerful ("boost") source of energy
 
T

tsmit420

Member
Nuecoyote said:
Isn't the whole premise of your initial post that citric acid was making phosphorus available?

I've also seen many who feel that as an anti-biotic citric acid can't be good for the beneficial bacteria in the soil. I'm not sure that's the case though. Unfortunately, I could find no reference to citric acid in "Teaming with Microbes" a highly recommended book for understanding the root zone of plants.

I'm wondering if, since this post questioning whether citric acid is effective in making phosphorus bio-available, you have learned any more or even sorted it out and could reconcile and resolve this to bring some closure to this thread.

Thanks
Click to expand...
teaming with microbes isn't really about the organic chemistry that is happening all the time in soil. organic acids are created by microbes, teaming with microbes is more about letting life be the chemist. until you read "teaming with nutrients"
the reason why citric acid can act as preservative that supresses microbes is because of the acidity and not any direct toxic effect, as long as it is accompanied by enough cations to balance the acidity then these acids become beneficial or at the very least causes no harm
 
Odin88

Odin88

Active Member
All I want to know is whether lemon juice and organic vinegars, when used as a ph down, will kill the beneficial microbes in a 100% organic grow? Are they going to kill the beneficial microbes in my soil? I use potassium bicarbonate as an ph up when needed.
 
Nutbag Poster

Nutbag Poster

Well-Known Member
How much difference does acid strength make when adjusting pH? If I adjusted the pH to 6.2 with a stronger acid like phosphoric , rather than citric, would it stabilize the pH quicker or maintain it's acidity longer. It seems to me that when I've used lemon juice or vinegar to lower the pH it tends to rise back toward 7.0 faster than if use commercial pH-Up. Is there anything to that?
 
ounevinsmoke

ounevinsmoke

Well-Known Member
Nutbag Poster said:
How much difference does acid strength make when adjusting pH? If I adjusted the pH to 6.2 with a stronger acid like phosphoric , rather than citric, would it stabilize the pH quicker or maintain it's acidity longer. It seems to me that when I've used lemon juice or vinegar to lower the pH it tends to rise back toward 7.0 faster than if use commercial pH-Up. Is there anything to that?
Click to expand...
yes, buffers
 
ounevinsmoke

ounevinsmoke

Well-Known Member
Odin88 said:
Ok. So it's useless to use potassium bicarbonate and lemon juice because they don't contain buffers.

Is it ok to use General Hydroponics ph up and down in an organic grow? Will it kill my microbes?
Click to expand...
The Bicarbonate is a buffer. Lemon juice is lemon juice. Acid and acidic solutions can and will kill bacteria if acid concentration is too high. You can breed your own microbes and add them periodically to help maintain substantial levels. Adding diluted acids is a preferred way to balance the PH of your solution. If your grow is "organic", why do you have to PH anything? Are you in soil or attempting Hydro/DWC organically?
 
J

James22v

New Member
Matt Rize said:
Here is the link to my blog, with many more posts. I lost all the formatting with the paste.

http://mattrize.blogspot.com/2010/10/citric-acid-and-cannabis-horticulture.html

"Citric Acid and Cannabis Horticulture:

Citric acid is a weak organic acid, it is a tricarboxylic acid, C6H8O7 . It is a natural preservative and used to make food taste sour, like 'sour patch kids' and soda. In biochemistry, citric acid is important as an intermediate in the citric acid cycle and therefore occurs in the metabolism of virtually all living things.

This post is all about citric acid.. The Cannabis growers of the world use citric acid to lower water pH for container gardens. Cannabis grown in soil-less organics prefers a soil(less) solution around 6.3 pH, and hydro is lower. A neutral water pH is 7.0, and my tap water is usually around 8.0 pH. So WHY do we use citric acid, and not the countless other acids, to lower our pH? The reasons are solid, let's investigate.
We need to begin by defining the important soil science terms that relate to soil-less organics.

Soil:
Layer of unconsolidated material found at the Earth's surface that has been influenced by the soil forming factors: climate, relief, parent material, time, and organisms. Soil normally consists of weathered mineral particles, dead and living organic matter, air space, and the soil solution.

Soil Solution:
Aqueous liquid found within a soil. This liquid normally contains ions released from mineral particles, organic matter or plant roots and leaves.

Soil Colloids:
Very small organic and inorganic particles found in a soil. Inorganic colloids are often clay particles. Soil colloids carry a negative electrical charge and are the primary sites for cation exchange. Soil colloids hold large quantities of elements and compounds which are used by plants for nutrition.

Ions:
An atom, molecule or compound that carries either a positive (cation) or negative (anion) electrical charge.

Cation Exchange Capacity:
The capacity of a soil to exchange cations with the soil solution. Often used as a measure of potential soil fertility.

Okay, now we have learned: what soil is, what a soil solution is, and how soil colloids play a key role in plant nutrition by holding elements and compounds.

BACK TO CITRIC ACID...

Citric acid is valuable as an additive in Cannabis horticulture for these reasons:

A. Citric acid (C6H8O7 ) bonds to Phosphorus anions (P-), making them soluble in the rhizosphere and soil solution.

Phosphorus anions (P-) are not easily mobile in the soil solution. The soil solution is a thin layer of water and microbes surrounding particles in media, soil-less and soil. Phosphorus anions bond with media particles, other elements, and organic matter. When bound P- is made insoluble and unavailable to plants roots. Citric acid bonds with P- and this keeps this needed nutrient in a form available to plant roots.

There are cations in the soil(less) solution. There are also cations in the cation exchange sites of media particles. Together these cations are held in equilibrium, but things can go wrong, especially in an unbalanced soil-less media. Managing this equilibrium is our goal.

By adding citric acid to our water and/or nutrient solution we release (solubilize) the Phosphorus anions. The roots can then use the ions in the soil solution and rhizosphere. The ability of roots to uptake all nutrients is directly dependent on pH of the solution, and the solubility of those nutrients. Citric acid (aka citrate) increases the bio-availability of Phosphorus anions (P-) present in the media.

B. Citric acid plays a role in the Krebs Cycle
Look for a post on this subject soon!

Look for an upcoming post on ROOT EXUDATES! Roots secrete all sorts of weak acids to free up N/P/K, Ca, Fe, and possibly other elements.

Root Exudates: (substances secreted by the roots).
Roots exude large amounts of citric acid into the grow media, this keeps the P- soluble in the rhizosphere and soil solution. This citric acid, and other acid root exudates , mineralize P- from organic matter like soft rock phosphate or bat guano.

Some good reading can be found below. Definitions were adapted from: PhysicalGeography.net.

1. Bioavailability of soil inorganic P in the rhizosphere as affected by root-induced chemical changes: a review
Philippe Hinsinger
Plant and Soil 237: 173–195, 2001.
(full text) http://www.plantstress.com/Articles/min_deficiency_m/P-bioavailability.pdf

2. Effects of root exudates on nutrient availability in the rhizosphere
A. Gransee
Plant Nutrition Developments in Plant and Soil Sciences, 2002, Volume 92, Symposium 9, 626-627,
(abstract only for now) http://www.springerlink.com/content/n216w5006k27754p/

3. Carbonic Acid Decomposition
Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois
(full text) http://www.newton.dep.anl.gov/askasci/chem99/chem99661.htm "
Click to expand...
I came here because I think growers are treating the buds themselves with citric perhaps as a THC preservative or even to improve THC availability. I have read THC-A degrades to CBN which is not as potent but still has some effects. Is it possible a quick spray after harvest with citric acid could improve cannabinoid profile in favor of THC-A??
 
cannabineer

cannabineer

Ursus marijanus
James22v said:
I came here because I think growers are treating the buds themselves with citric perhaps as a THC preservative or even to improve THC availability. I have read THC-A degrades to CBN which is not as potent but still has some effects. Is it possible a quick spray after harvest with citric acid could improve cannabinoid profile in favor of THC-A??
Click to expand...
THCA decomposes to THC directly.
THC oxidizes to CBN via another mechanism.

How adding citric acid will affect either reaction I don’t know.
 
Odin88

Odin88

Active Member
ounevinsmoke said:
The Bicarbonate is a buffer. Lemon juice is lemon juice. Acid and acidic solutions can and will kill bacteria if acid concentration is too high. You can breed your own microbes and add them periodically to help maintain substantial levels. Adding diluted acids is a preferred way to balance the PH of your solution. If your grow is "organic", why do you have to PH anything? Are you in soil or attempting Hydro/DWC organically?
Click to expand...
I'm using Fox Farm soil. I only recently learned that ph'ing isn't necessary with an organic grow.
 
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