The Myth of Low N

[grapeman]

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."

I'll post up some pics of the lo bi urea and epsom mg sulfate I use when i get a chance.

As to your second comment..... well that's the trick really isn't it. to keep your plants healthy and happy with N without over doing it. IMO, this varies GREATLY by strain. Too many grows with different strains with the same nute regimen and it is obvious that 1 method DOES NOT fit all. So it gets back to using the tables and charts as a tool to tailor your soil mix or nute schedule then dialing it in as you perfect your "Art" of growing over several grows.

 

[YosemiteSam]

Thanks Basement Breeder. Your explanation actually makes perfect sense. That fits perfectly with what I have observed with me own peepers.

Avenger...thank you for those. Looks like I have some serious reading to do.

 

[desertsquirrel]

This draws water out of the roots, causing nute burn.

Nute burn is caused by plants growing too fast. This causes cells to elongate and eventually burst, looking like they have been "burned." Self-regulation happens, but its not like ordering a meal from a restaurant. Thats why imo its so important to get the solution profile as close as possible to the profile of the plant tissue taking up the solution.

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?).

Your correct. N, K, and Ca. Charts posted below.

 

[BasementBreeder]

desertsquirrel,

Do you have any links to info on the cause of nute burn? I've been having a difficult time finding anything. I'll try to find the info for why I thought it was caused by water loss in the roots, but not sure I'll be able to.

When I said "Plants don't use each nutrient at the same rate" I should have said uptake instead of use. Plants certainly use large amounts of Ca, however it is uptaken passively, so it tends to stay in nute solution longer than say, K or N.

 

[grapeman]

http://aob.oxfordjournals.org/content/89/7/841.full.pdf

LOL

 

[BerndV]

Not saying anyone is wrong but I have always wondered...if marijuana actually self regulates how do people manage to nute burn it?

Cannabis only self-regulates nitrate nitrogen uptake. Too much phosphorous, potassium, or ammoniacal nitrogen will "burn" a plant.

 

[BerndV]

.

 

[desertsquirrel]

desertsquirrel,

Do you have any links to info on the cause of nute burn?

Its based on a lecture i was at during school. Sorry i dont have any sources for it. Wish i did.

 

[BasementBreeder]

on page 41 of Hydroponics: A Practical Guide for the Soilless Grower by J. Benton Jones Jr.

Instructions frequently call for the total N concentration in the nutrient solution to start at a low level(<100 mg/L, ppm), which is then increased as the growing crop matures. This is a common practice in the case of fruiting crops, when control of the N supply is set to minimize excessive vegetative growth and to promote fruit initiation and development. Since N is a key essential element affecting plant growth and fruit quality, careful control of its supply to the plant is extremely important.

On page 223, a nutrient solution(from the proceeding of the Greenhouse Tomato Seminar, 1995) for tomato (ppm) is given. The levels of N in each stage of growth is as follows: Stage 1= 70, stage 2= 80, stage 3= 100, stage 4= 120, stage 5= 150.

In contrast to the increasing levels of N, another tomato stock solution(from Morgan, L., 2003, The Growing Edge) is given as follows: Day 0(flowering)= 350, Day 10= 350, Day 20= 345, Day 30= 322, Day 40= 315.

Then of course there is A. Steiner who recommends running his nute formulation throughout the course of the grow.

So overall, I'm not sure on the level of N to supply. I'd love to see some data for plants that were vegged more than 1 week before flowering.

 

[YosemiteSam]

Confusing ain't it.

That Steiner soln sure has a lot of Ca and K in it. I am basically trying something very similar with marijuana right now.

I like to start with lower N and work my way up to a peak at the end of stretch, then back it down and up P and K. Who knows if that is a good way or not.

Damn the lack of statistical analysis on this plant.

 

[desertsquirrel]

Epsom profile:

im pretty sure this is correct, but im not 100%. Please let me know if the numbers are off.

Epsom salt, magnesium sulfate, Mgso4:

Mg: 9.8%
S: 13%

1g Epsom salt =

Mg: 98 mg or 98 ppm/liter
S: 130 mg or 130 ppm/liter

or

1g/10 liters =

Mg 9.8 ppm
S 13 ppm

 

[YosemiteSam]

Epsom's numbers as I recall...in ppm for 1 gram per gallon...are 25 ppm Mg and 33 ppm S. Make your own conversion from there, I am sticking with grams and gallons

 

[desertsquirrel]

ppms are already in mg/l. it just makes it easier. but thanks for confirming the math.

 

[YosemiteSam]

DOH...you are totallly right.

Sorry I was being such a stubborn asshole. I get that way from time to time...it might be time to smoke a bowl

 

[desertsquirrel]

lol. embrace the metric. u will love it.

 

[ShroomDr]

So overall, I'm not sure on the level of N to supply. I'd love to see some data for plants that were vegged more than 1 week before flowering.

I dont have any data sets, but i veg for WAY over a month. I have plants in flower right now that were rooted clones from the end of Oct (I train the shit out of them, 3 or 4 growth tips, all at equal height, trained vertically, creating a trellis with bamboo stakes and zip-ties).

I never go over 110N (maybe 115N if the bitches are Cal-Mag whores), and it normally stays in the 85-95N range.

 

[desertsquirrel]

you running the 85-115 N profile until flush? or you cutting it back earlier?

 

[ShroomDr]

No, thats just where i max out. i thought i said earlier, that i drop it to < 40-50 about 75-80% though flower.

 

[grapeman]

Here -

http://www.plosone.org/article/info...PlantBiology+(PLoS+ONE+Alerts:+Plant+Biology)

 

[Storm Shadow]

Where is Spurr at? His input on this topic is most def needed