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The Myth of Low N
- Thread starter desertsquirrel
- Start date
Y
YosemiteSam
Is it possible it had more N in the tissue because it was overfed N and just accumulated it in the tissue?
I mean what we get fed as humans effects our body composition. A fat kid fed donuts ain't gonna have the same chemical tissue analysis as a Tour de France rider fed a gluten free diet.
I would seriously think about making that leap all at once. Seems like a sneak up on it kinda thing to me.
I am also curious about the taste/N relationship. Is there any science behind that or is it just the consensus amongst a bunch of growers.
I mean what we get fed as humans effects our body composition. A fat kid fed donuts ain't gonna have the same chemical tissue analysis as a Tour de France rider fed a gluten free diet.
I would seriously think about making that leap all at once. Seems like a sneak up on it kinda thing to me.
I am also curious about the taste/N relationship. Is there any science behind that or is it just the consensus amongst a bunch of growers.
Just wanted to post this here, it's based on the same datas as the first chart in the first post.
source
Notice that WR had lower N content in Flo than in Veg.
The N-taste relation seems straightforward:
high N -> more plant material with more chlorophyll -> more smoke
Although I'm not sure about the biochemical background.
But since N is highly mobile and I haven't seen yellowing flower clusters caused by N deficiency, maybe because the plant tries to maintain a healthy level of N in the flowers by deriving it from the lower leaves rather than forming N deficient flower clusters it cannot be lowered below a certain level just by using a low N feed regime.
Maybe light derivation could be used to lower chlorophyll content in the flowers.
source
Notice that WR had lower N content in Flo than in Veg.
The N-taste relation seems straightforward:
high N -> more plant material with more chlorophyll -> more smoke
Although I'm not sure about the biochemical background.
But since N is highly mobile and I haven't seen yellowing flower clusters caused by N deficiency, maybe because the plant tries to maintain a healthy level of N in the flowers by deriving it from the lower leaves rather than forming N deficient flower clusters it cannot be lowered below a certain level just by using a low N feed regime.
Maybe light derivation could be used to lower chlorophyll content in the flowers.
desertsquirrel
Member
Of course we cannot make any over arching conclusions based on this one sample. But its hard for me to ignore the implications as well... I should be doing my own leaf/stem/bud tissue analysis over the summer i hope that will help.
Assuming big mike used his own nutes at his own application rates he provided far less N proportionally then was actually found in the plant... Im very interested in why....
The other main question im asking is "when is the optimal time to cut n?" Can you run a high N right up until flush if you flush properly? or does it need to be dialed back to week 4? or 5? I have experienced ur yellow school buses at day 30 with far too many nute lines to ignore it.
And thanks for posting those samples tester.
Assuming big mike used his own nutes at his own application rates he provided far less N proportionally then was actually found in the plant... Im very interested in why....
The other main question im asking is "when is the optimal time to cut n?" Can you run a high N right up until flush if you flush properly? or does it need to be dialed back to week 4? or 5? I have experienced ur yellow school buses at day 30 with far too many nute lines to ignore it.
And thanks for posting those samples tester.
BasementBreeder
Member
We can't really "force" plants to uptake nutrients. As long as both the major cations and anions are (roughly) balanced the plant will take up nutrients in the ratio it needs.
I can provide sources for this if needed.
unfortunately your also assuming that was was listed on the label 8 years ago was accurate, when last year their labels were off.
I would say it is somewhat strain dependent, but basically after 75-80% though flower i keep the N @ or below 35-40ppm (and no NH4 after the first 10%, if that). So a 10 week strain in my garden doesnt get much N after week 6-7 .
Again its all plant dependent, and dosage dependent, but feeding Cal-Mag @ week 7 on a 9 week strain is not going to help anything (Its going to make your buds taste harsh/chemy/green/shitty).
@desertsquirrel If you are attempting the N:K 1:1 what ppm are you shooting for, and what substrate? I (re)use coco, so i never really know my K level.
desertsquirrel
Member
I am running most media (RDWC, Rockwol, hydroton, coco and soil.) I would probably use the rockwol or RDWC for the test, and try to increase the ratio by .2:0 per harvest from 1:2 until it stops seeming of benefit.
I flush all media for last 20-25% of the flower time so i am wondering if i should just run it all the way to flush or stop at week 4-5.
And LoL at the AN labels.
desertsquirrel
Member
Assuming An used thier own products to build the tissue they sampled they did the opposite of "force" N. Solution ratio was around 3-1-5 and the tissue using that solutions ratio was 5-1-4.
Not sure how what your talking about is relevant, or who/what is forcing anything. I like sources though.
I'm not so generous. I think AN might use urea/ammonicals because they are much cheaper to use and mix.
In other crops where we buy in bulk and or have blends made for our specific use, urea is only used in the early stages of growth and we plan for a percentage of N becoming available over time as the urea breaks down. In later stages of growth, we use products such as AN20 or CAN17 (much more expensive) so we can further control available N towards harvest. In fruit growing, too much available N at the end of the fruiting cycle will delay sugar formation and ripening. IMO, it will do the same on this crop.
Urea (lo-bi urea in small amounts like 1 to 5 lbs in a 600 gallon spray tank) is an excellent addition to any foliar feed. It provides a bit of N and it seems to act as a carrier as it drags other nutrients into the leaf with it. An excellent foliar feed in early flower would be Lo-bi urea and epsom salts. I use ag grade epsom salts as they are easier to mix. This gives a boost of N and Mg.
My 2 cents.
desertsquirrel
Member
Fantastic suggestion, can you post the urea and ag grade epsome source you use for foilars please?
Im not questioning that too much available N is counterproductive for fruiting/flowering plants. My question is, based on the actual presence of N in quality (i hope) flowers, how much N is "too much."
BasementBreeder
Member
I was just responding to your question about the disparity between nute solution and tissue solution ratios(see what I quoted in my first post). I interpreted your question as 'why does the tissue ratio not match the solution ratio'. Did you mean 'why does AN use the solution ratio they do when the tissue analysis would dictate the use of a different one'?
selective capacity of plants for ions
IMO. Knowing what too much N is is in some part subjective. In other words I can make my plants (any plant really) very happy a with continued supply of N. I can increase the supply and all will be well until it isn't. Crop will be delayed. Fruit will suffer or ripening delayed or burned to a crisp.
In other crops I grow, much money and research has been applied to guideline ranges of NPK levels and micro elements levels. It seems that what I've seen herein is good, but maybe a bit lacking in repetition.
The ONLY way to determine the right way is to start with the guidelines and increase or decrease nutrients as your experience and "eye" tells you. But you can get many "seasons" under your belt in 1 year. In other crops I grow, the learning curve is in decades. And this will vary by variety or strain.
The science of growing or farming will get you in the ball park while the "art" of farming or growing will enable you to hit home runs. If you strive to follow the book or the charts, you may have good success, but will never have great success. Once again, IMO.
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desertsquirrel
Member
You said it perfectly grapeman. that is the exact goal of the thread. Great to have your input.
desertsquirrel
Member
those sources look excellent basementbreeder, thank you for posting them.
BerndV
Member
Canna has done a considerable amount of research on optimum nutrient profiles for growing cannabis. For example, the amount of N supplied by their Coco A&B in the light-to-heavy feeding dose of 8-12 ml/gal is 123-184 ppm. Following their recommended feeding regimen, including a thorough flush for the last two weeks, produces connoisseur quality herb every time and very healthy looking plants. My recent SLH grow did just fine on 8 ml/gal of Coco A&B. However, my current crop (see below), other than the Rez gear, becomes noticeably N deficient on anything less than 12 ml/gal. However, because cannabis self-regulates nitrate nitrogen uptake, all of my current strains are doing fantastic on 12 ml/gal.
Y
YosemiteSam
Not saying anyone is wrong but I have always wondered...if marijuana actually self regulates how do people manage to nute burn it? And why don't people just load it up with the major nutes and let it pick and choose what it wants to eat? Why would people flush?
perhaps cannabis can only regulate nutrient uptake in an organic "live" soil based environment (where actual breakdown occurs) and not in a "hydroponic" chemical nutrient regiment where the nutrients are immediately available to the plant.
slow vs fast?
(analogy) getting food through the mouth where the food will start breaking down via your saliva and the enzymes there compared with getting an IV full of nutrients/sugars/etc. which one works quicker? more efficient? potential for problems?
does the plant work harder to eat from organic soil?
it has been proven that hydro based growing is faster than soil based. must be the nutrients available to the plant. it has also been proven that it is much harder to burn plants via organic soil being fed organic food/teas.
BasementBreeder
Member
My hypothesis...
Plants don't use each nutrient at the same rate. I believe N and K are used the quickest, but can't remember where I read that(maybe someone else can confirm/deny?). If we continually apply nutrients in the wrong ratios/amounts, there will start to be a build up in the medium of the less used ions. Eventually this buildup reaches a level where the ionic concentration is too high (higher than in the roots, IIRC). This draws water out of the roots, causing nute burn. Also, the paper I linked to above(the one by Abram Steiner) says that plants uptake ions in a favorable ratio, as long the ions in solution are within a certain(fairly wide, imo) ratio range. Perhaps if they aren't, then nute burn happens as certain ions get locked out(causing a buildup in the medium).
I'm not sold on flushing one way or the other. My gut tells me that a perfectly fed plant would not need it. On the other hand, the plant's goal is survival, not to produce the best tasting buds, so it may take up nutes at the end of its life that are detrimental to taste/flavor.
