Basic(ish) inorganic nutrient chemistry

[Audionut]

How are you or do you plan on defining and measuring the optimal concentration of individual elements required to support the life cycle of each individual phenotype of Cannabis you are or plan on growing?

 

Would there be a significant difference between a plant grown at the 90th percentile compared to one grown at the hypothetical (because nothing is perfect) 100th percentile and would this difference be commercially viable to attempt to attain?

 

It would be interesting to see your approach put into practice. At the moment it seems like you have loaded yourself up with a lot of information and now need to sort out what is and is not practical or achievable.

 

Thankfully, there is no "optimal concentration" in the manner I believe you suggest.  Consider the following graph, and a quote from the last page.

 

http://s22.postimg.org/aa36lrmdd/Nutrient_concentration.png

 

 

Ratios between nutrients only really shows us that we need more of some nutrients then others.  There is no one specific ratio of nutrients that provides optimal growth.  The goal is simply to ensure adequate supply of all of the nutrients.  If the plant has too little of a nutrient then it struggles to perform certain processes required for growth and begins to show deficiency symptoms, with decreasing supply leading to decreasing ability to grow, up to the point of death of the plant.  At some concentration, there will be an excess of a nutrient to the point where it also begins to effect plant growth, and again increasing concentration can lead to plant death.  But there's actually quite a wide band of nutrient concentrations with which the plant will grow without distress.

 

This "wide band" is the luxury consumption (or luxury uptake).  If the plant growth was at the left hand side of the graph, it would have a high response to ferts, meaning that if ferts were applied, it would have a large growth rate response.  If the plant already has some luxury consumption, then it would have no response to ferts (positive or negative), but if you continue to increase nutrient concentration you would eventually begin to poison the plant.  Follow the red line in the image above.  Starting at a concentration of zero ppm of some inorganic mineral, small increases in concentration have a massive effect on plant health and growth, and as concentration continues to increase, the amount of increase in plant growth begins to taper away from the amount of added inorganic mineral.

 

Finding specific numbers is not my intent.  To do so requires plant tissue analysis (and soil analysis if grown in soil) which I do not have access to, and would only provide specifics to those people who like specifics anyway.  For those people using inert growing medium (or hydroponics), there are plenty of resources online describing nutrient concentrations for plant growth.  One such is the Hoagland solution.  I use a derivative of the Hoagland solution in my aquarium, although given that the water must also support fauna the concentrations are highly diluted from the original Hoagland solution.

 

When I say ferts, I really mean inorganic minerals, since it is these inorganic minerals that the plants can use.  You can supply these inorganic minerals via organic substances, or inorganic salts.  Organic sources of these inorganic minerals have the advantage of maintaining soil viability, but it also has some disadvantages such as the increase in almost all inorganic minerals (very rarely an issue), and the slow release of inorganic minerals, since it simply takes time for life to break down the organic minerals to inorganic minerals.  Inorganic salts have the advantage of instant supply of the needed inorganic mineral (ceasing an increase in deficiency symptoms immediately), but the disadvantage of not fixing the fundamental problem.  Of course in situations without soil growing mediums, inorganic salts are the only viable solution.

 

 

Ph balance is the main consideration I think you need to consider. Its one thing to balance the ph of the mix at the start but controlling the drift as the cation exchange occurs will be a whole other matter.

 

 

IMHO, there is no one main consideration, but I'm probably just being argumentative.    pH isn't going to be an issue if there is no light, or water, or inorganic minerals.  pH is simply an indicator.  Most people probably only associate pH with Hydrogen concentration, but we can use pH to describe the chemical species of various elements.  In a solution, this is represented with a Pourbaix diagram.  Also see: https://www.wou.edu/las/physci/ch412/pourbaix.htm

 

As I've mentioned previously, my knowledge of soil interactions isn't where I would like it to be, so I can't accurately describe how the chemical species react in soil, except to say that it follows the same principles as in a solution.  I do know that the plants can excrete H⁺ ions from the roots, causing the surrounding soil to become more acidic and thus helping to push the chemical elements into species that are available to plants.

 

Cheers.

[forgetiwashere]

PH is definitely a major consideration as certain nutrients can only be absorbed through certain PH ranges so keeping that PH in check is paramount. if you dont you will have deficiencies everywhere.

 

as im sure you know, when the plant takes in the nutrients its an exchange of ions and anions, the plant will exchange its free hydrogen atoms. so OH- and HO3+ to keep the balance. that exchange causes the PH to shift.

 

basically the nutrient companies that make canna specific nutrients understand which nutrients canna uses the most of and which ones have the highest effect on PH and balance it. so lets say nitrate NO3- is absorbed by the plant it will have to give back something to keep the balance so it gives back an OH-.

similarly potassium K+ will be exchanged for HO3+

 

so knowing this and knowing its effect on PH drift nutrient companies can sub in other forms of nutrient so that as the nutrients are absorbed they will actually cancel each other out and keep the PH stable. so for example Nitrogen uptake is having the largest effect on your PH you can sub in some ammonium NH4+ this way as the ammonium is absorbed alongside the nitrate it can help keep each other balanced.

 

of course thats a very simplified version. honestly its all over my head but of you google it you will find plenty of info.

 

EDIT:- its also something you will need to consider is the medium your going to use is something you will have to consider because each medium will have absorb certain amounts of nutrient as well and you need to allow for that

Edited March 13, 2016 by forgetiwashere

[Audionut]

Ok, so trying to be light hearted isn't working.

 

What exactly is HO3+?

[forgetiwashere]

hydroxide (OH⁻) and hydronium (H₃O⁺).

 

pretty sure they are hydrogen free radicals which the plant creates through its process's and releases  as waste to balance the cation exchange. again im no scientist and i dont fully understand it all so im not trying to school you or anything but i do try to understand most things around me and why they work so i can understand why im doing what im doing and why things happen the way they happen. i know enough to know i know nothing hahaha
 

 

Oh i just realised i was writing HO3+ sorry im rusty

Edited March 13, 2016 by forgetiwashere

[Audionut]

Well I have a healthy knowledge of inorganic mineral behavior in aqueous solutions, but would loved to be schooled on mineral reactions in complex soils.  Would save me the time it will take to learn and understand it myself. 

I know just enough to be dangerous.

 

I'm pretty sure that plants will only excrete H⁺, but in either case, the point stands that there is a pH shift.

 

Fascinating stuff really.  Wish I paid more attention in school.

 

Cheers.

[Naycha]

I say germinate some seeds and put theory into action.

[billygoat]

I say germinate some seeds and put theory into action.

+1

[forgetiwashere]

Well I have a healthy knowledge of inorganic mineral behavior in aqueous solutions, but would loved to be schooled on mineral reactions in complex soils. Would save me the time it will take to learn and understand it myself.

I know just enough to be dangerous.

 

I'm pretty sure that plants will only excrete H⁺, but in either case, the point stands that there is a pH shift.

 

Fascinating stuff really. Wish I paid more attention in school.

 

Cheers.

It's a great topic and I won't pretend to know it all so instead here's a great article from a great site.

 

http://scienceinhydroponics.com/2010/06/understanding-ph-in-hydroponics-part-no-1.html

[forgetiwashere]

I enjoy learning all this stuff. It's why I grow in hydro and have for decades. I could learn these things and understand how they work. In understanding I can grow better.

 

Soil to me was all black magic and voodoo to me up until recently when I started to understand the science behind that too. But for me hydro will always have a place in my garden

[Audionut]

To control pH in my aquarium, I use the automated dosing of citric acid and bicarbonate.

 

CO₂ + H₂O <> H₂CO₃ <> HCO₃^- + H⁺ <> CO₃^2- + H⁺

 

I like to use potassium bicarbonate and calcium carbonate since I need potassium and calcium anyway, with the net chemical reaction leaving a chelate, carbon dioxide, water and potassium.  If I went hydro I would use the same methods, since the reaction on pH between citric acid and bicarbonate can easily be greater then the reaction on pH of all of the other salts...........combined.  Did I mention a chelate, carbon dioxide, water and potassium, all from just two salts.  Nifty stuff.

 

https://en.wikipedia.org/wiki/Citric_acid

https://en.wikipedia.org/wiki/Bicarbonate

https://en.wikipedia.org/wiki/Carbonic_acid

https://en.wikipedia.org/wiki/Carbon_dioxide#In_aqueous_solution

https://en.wikipedia.org/wiki/Bjerrum_plot

https://en.wikipedia.org/wiki/Chelation

Edited March 13, 2016 by Audionut