The Myth of Low N?

[H3AD_CAS3]

Besides week one where i might go high with P I still am only at 80 ppm I normally ride around 55-60 ppm. JK
My bios do not care to go over 70 PPM

does this matter what media the plants are in?

 

[Jalisco Kid]

does this matter what media the plants are in?

Well I guess it could matter on the ppm and the medium. I am not a dirt farmer but I believe they use more P because it flushes away with each watering. I know from looking at stained slides you can see the damage from P on the bio herd once it goes over 65 ppm. JK

 

[Capulator]

bump..

 

[squiggly]

Can you help me understand the tissue analysis? couldn't the plant just be storing the N in its tissue, and not actually using it? Kind of like foraging for a possible drought?

While there is probably some of this "type" of nitrogen hanging about in the tissue--most of what you are looking at in ANY biological tissues sample of a multi-celled organism in terms of nitrogen is being expressed as a structural component in macromolecules.

DNA is a significant portion of this, as it is constantly being multiplied and is VERY VERY efficiently packaged such that its density is very high--N is a structural component of this macromolecule--and is present in every "base" thereof.

The backbone (main chain) of ANY protein goes N-C-C-N-C-C-N-C-C ad nauseum.

Again proteins are extremely dense and well packed (though not as well as DNA)--and there are also many nitrogenous side chains on proteins. We haven't even gotten into lipids, of which many also contain nitrogen (and depend on it for proper function).

Nitrogen which is not being used for something is generally sequestered for waste in most organisms (not super sure in plants, but I can't imagine its much different)--because if its not being used as a molecular component it likes to oxidize stuff. Organisms do not like oxidative stress--and it is for this reason that a huge component of our waste as humans is nitrogen. We need it every bit as much (if not more) than plants, but if its not being put to immediate use it is very damaging.

The body spends an incredible amount of energy, and has several separately evolved pathways for dealing with nitrogen--it really is important stuff.

As far as biochemistry goes, if I had to rank my top 4 most important elements I'd say

1. C (ubiquitous--not really worth mentioning here)
2. P
3. N
4. S

Obviously the others are important--but in my opinion the above 4 (with carbon being obvious) are the most important to get right, or dial in.

Phosphorous is really the golden ticket. Its what makes everything go round, its energy currency. If you get thru a few semesters of advanced biochem classes--it becomes very obvious what a huge effect a small change in P availability can make.

Nitrogen must be maintained at the exact correct level for optimum growth. Too much and it becomes very toxic very quickly, too little and you're well behind where you could be. Shortage of even 1 N molecule might mean that 1 enzyme doesn't get completed. That enzyme may have gone on to do 100K reactions a minute for the next 2 days had it been completed. That's a retarded effect.

S is enzymatic gold. Can't do anything cool in the plant without this stuff. Not nearly as toxic (in the amounts we'd routinely add)--but equally as damaging if its deficient. Terpene and THC synthesis require proper sulfur availability as an absolute precondition.

As for micros, I'll add in for fun,

Molybdenum is a cofactor for one of the synthase enzymes that creates precursor molecules for THC-a synthesis. While the THC-a synthase was found not to require cofactors, this is a very important one in the chain.

 

[Capulator]

While there is probably some of this "type" of nitrogen hanging about in the tissue--most of what you are looking at in ANY biological tissues sample of a multi-celled organism in terms of nitrogen is being expressed as a structural component in macromolecules.

DNA is a significant portion of this, as it is constantly being multiplied and is VERY VERY efficiently packaged such that its density is very high--N is a structural component of this macromolecule--and is present in every "base" thereof.

The backbone (main chain) of ANY protein goes N-C-C-N-C-C-N-C-C ad nauseum.

Again proteins are extremely dense and well packed (though not as well as DNA)--and there are also many nitrogenous side chains on proteins. We haven't even gotten into lipids, of which many also contain nitrogen (and depend on it for proper function).

Nitrogen which is not being used for something is generally sequestered for waste in most organisms (not super sure in plants, but I can't imagine its much different)--because if its not being used as a molecular component it likes to oxidize stuff. Organisms do not like oxidative stress--and it is for this reason that a huge component of our waste as humans is nitrogen. We need it every bit as much (if not more) than plants, but if its not being put to immediate use it is very damaging.

The body spends an incredible amount of energy, and has several separately evolved pathways for dealing with nitrogen--it really is important stuff.

As far as biochemistry goes, if I had to rank my top 4 most important elements I'd say

1. C (ubiquitous--not really worth mentioning here)
2. P
3. N
4. S

Obviously the others are important--but in my opinion the above 4 (with carbon being obvious) are the most important to get right, or dial in.

Phosphorous is really the golden ticket. Its what makes everything go round, its energy currency. If you get thru a few semesters of advanced biochem classes--it becomes very obvious what a huge effect a small change in P availability can make.

Nitrogen must be maintained at the exact correct level for optimum growth. Too much and it becomes very toxic very quickly, too little and you're well behind where you could be. Shortage of even 1 N molecule might mean that 1 enzyme doesn't get completed. That enzyme may have gone on to do 100K reactions a minute for the next 2 days had it been completed. That's a retarded effect.

S is enzymatic gold. Can't do anything cool in the plant without this stuff. Not nearly as toxic (in the amounts we'd routinely add)--but equally as damaging if its deficient. Terpene and THC synthesis require proper sulfur availability as an absolute precondition.

As for micros, I'll add in for fun,

Molybdenum is a cofactor for one of the synthase enzymes that creates precursor molecules for THC-a synthesis. While the THC-a synthase was found not to require cofactors, this is a very important one in the chain.

Great info. Let's say I had a nitrate meter and could measure N in a drop of sap... How do I take the info (ppms N in sample) and apply it to how much N to add or take away?

Here is a meter: http://www.specmeters.com/nutrient-management/nutrient-meters/nitrate/cardy-twin-nitrate-meter/
There is a description of the right ppms for sap nitrate for a tomato.

Is there a guidline for cannabis? Furthermore, is the N uptake strain specific?

 

[squiggly]

Is there a guidline for cannabis? Furthermore, is the N uptake strain specific?

Probably not, and almost certainly yes.

 

[Capulator]

Probably not, and almost certainly yes.

Yeah I looked all over this morning. Found all the fruits and veggies ppm sap guidlines, but cannabis is a flowering plant not a fruiting one.

 

[Blaze]

I have yet to see sap guidelines for cannabis. I can tell ya this much though - it uses far more N than any other plant out there. Still trying to figure out what the upper limit is, have not hit it yet (at least w/ soil).

 

[reeldrag]

great thread guys i have hit the upper end of N it wasnt pretty (insert lots of crying here) while MJ does seem to handle very large amounts of nutes there are some very cool reports that show there can be a slowing of growth and flower size from over 1200ppms with zero visable damge to the naked eye. Is it possable we maybe shooting ourselves in the foot trying to make a perfect mouse trap i do enjoy this topic cuz I think we r all trying to maximize our loved ones

 

[desertsquirrel]

1200 is much higher then i would ever go...

Tweeking N does not mean jacking the EC/PPM.

 

[Seamaiden]

I can't get sap from ANY of my plants to get a Brix reading. All that happens is the leaves turn to mush. WTF? I want to get sap and take a reading.

 

[desertsquirrel]

Sap extraction is fucking me right now too seamaiden. lemme know if u get anywhere.

Having the best luck - though not much - w petiolas. How about u?

 

[Seamaiden]

No one's answered me as to whether or not I can use petioles. Squash and cucumber leaves are among the worst to try to get sap from, so if I can use those that might be helpful.

 

[Blaze]

Do the petioles, juicing leaves is a PITA. Use a garlic press to extract the juice, it does take quite a few to get enough.

 

[Seamaiden]

Juicing the leaves is pretty much impossible. I'll start on the petioles today! Right after I trellis up a girl who went down with the rain. D'oh!

 

[LexLuthor]

GH MaxiGro has a decent veg formula, for shoot growth that is. This is at 5 grams/Gallon N 132 P 29 K 154 Ca 79 Mg 26 S 40.

I know Ca and Mg seem kinda low compared to N, but it fits the leaf samples pretty good. Also, if you wanna boost P and K during flower just use GH KoolBloom which is P 68 K 130 at 5 ml/Gallon, obviously you would only use 1-3 ml/Gallon of KB. Its not great by itself, but with the addition of epsom salt and a Ca-Mg supplement, you could grow from seed to harvest with just those 4 products and have a relatively good nutrient profile.

 

[jfizzle2cmu]

So basically phosphorus and calcium lock up all the other nutrients and all the other nute lock up c and p lol? Got it.

 

[Capulator]

So basically phosphorus and calcium lock up all the other nutrients and all the other nute lock up c and p lol? Got it.

No. Take a look at mulders chart for this.

 

[jfizzle2cmu]

I did...that's what I was referencing. I think I'm wrong on the second part, but calcium and phosphorus lock out a bunch of stuff. Most of the others are about a wash. Seemingly would it make sense to set phosphorus and calcium levels first and adjust everything else around those as the other nutrients only react negatively with one or two things as opposed to several?