Testing fertilizer strength on tobacco seedlings

[billy]

Since many wonder if there over fertilizing or under fertilizing, or how bad urea is on seedlings. or maybe they cant trust their results cause they arent sure if the problem is low light ect.
im testing various strengths with common miracle grow tomato food
conditions are.
400 PPFD of light during the day, which is plenty for any size seedling.
fans for air flow 24/7
about 70-75f day temp, maybe 10 degrees lower some nights
soil is Pro Mix BX mycorrizae. which is peat, perlite, vermiculite, and tiny bit of dolomite lime for PH adjustiing the peat. so its basically nutritionless apart from some calcium and magnesium from lime.

Fertilizer. miracle grow tomato food, which contains urea. default strength of 1 means 1TBSP per gallon
Plant 1: water only control
Plant 2: 0.25 Strength
plant 3: 0.5 Strength
plant 4: 1 Strength
plant 5: 1.5 Strength
Plant 6: organic control



the organic control is, soil half Pro Mix, half well aged compost of various plants and manures live bugs and all, and some perlite to make up for compost diluting the ProMix's perlite
fertilizer for that is Grow 12-6-6 at Half recommended full strength, thats made of fish, feathers and seaweed

Test potential problems:
you may have noticed they arent the same tobaccos, since this wasnt planned i just had them from germination testing and didnt want to kill them, and my light was running anyway so i figured id do a test with them. i dont think this will matter much, the shorter and faster types i had weren't included. but im sure fertility varying by that much will give plenty of variation to notice.
also they were separated and transplanted into here from other containers. i worked very slow and careful not to damage roots and transplant well but that may have some effect compared to if this was thier original planting from seed. also they were growing in "Plant 6 conditions" prior to this. so this isnt a test as if they never had any nutrients so far. its just testing a healthy seedling root transplant from this point onward.

they were seeded on 3/20 and today 4/4 is day 1 of test and they were given their different fertilizers until it started to drip from bottom, since obviously bottom watering isnt an option here
ill post whenever something is noticeable


also feel free to place bets on which will do well or poorly lol

 

[Knucklehead]

Regarding urea:

North Carolina State University

https://tobacco.ces.ncsu.edu/wp-content/uploads/2016/12/Tobacco-Seedling-Nutrition-in-the-Greenhouse-Float-System.pdf?fwd=no

Page two
"Other Fertility Concerns"
"Urea has been found to be toxic to tobacco seedling in the float system." ...

University of Kentucky

http://darktobacco.ca.uky.edu/files/floatsystems-greenhousesweba.pdf

"Source of Nitrogen"
"Nitrate -
+ Best
+ Readily available form

Ammoniacal
+ Marginal
+ Ammonium form

Urea
+ Worst
+ Can convert to ammonia or nitrate which can be toxic to plants. "

There are more, those are two samples from universities located in tobacco growing regions.

My personal fertilizer recommendations are based on conversations with a multi generational tobacco farmer that has grown hundreds of acres of tobacco for R.J. Reynolds his whole life, following the footsteps of his father and grandfather. (possibly further, for sure three generations.) He recommended 20-10-20 urea free. It just happened to be labeled as an orchid fertilizer. (marketing) The guy follows the research and the recommended practices demanded by R.J.R. if he wants to keep his contract. I have never seen a study or even a person trying to say that urea free fertilizer will kill tobacco seedlings. There are academic studies from universities in tobacco growing regions recommending urea free as well as evidentiary testimony of folks that lost their seedlings. Some folks here say they have used urea for ten years and gotten away with it, but statistically that is an extremely small sample size and contrary to recommendations compared to scientific studies and generations of tobacco experience. For me personally, it's not worth the risk.

Here is where I stand on the practice personally. I cannot recommend the practice to a first year newbie that already has too many variables, uncertainties, and feels a little overwhelmed and unsure about himself. If his first crop gets wiped out, he may become disillusioned and discouraged and never grow again. Being unwilling to have that on my conscience, I will continue to recommend urea free fertilizers for seedlings, especially for newcomers to the hobby and for those folks with short seasons that may not have time to start over again should the worst happen at the worst time.

I post this with the full measure of respect for those that hold the opposing view. I value your opinions and experience. I am posting my opinion and cited sources for those that would like to read them and come to their own conclusions.

 

[billy]

all good. i dont necesarily think people should use urea on seedlings. but i just dont think float tray research is relevant. hydroponics is a whole separate can of worms and most all of us blog growers aren't using it. it may be the case that bacteria that covert urea cant live underwater so its worse there, maybe a certain amount is bad. or maybe its worse in sterile mix. i dont really know, so im starting to do testing and see what i can learn about it.

i want to add on a test with compost mixed soil with rich biology, then see if the biological one can handle higher amounts of urea before the plant are damaged. and hopefully at one point ill figure something out.

 

[Knucklehead]

all good. i dont necesarily think people should use urea on seedlings. but i just dont think float tray research is relevant. hydroponics is a whole separate can of worms and most all of us blog growers aren't using it. it may be the case that bacteria that covert urea cant live underwater so its worse there, maybe a certain amount is bad. or maybe its worse in sterile mix. i dont really know, so im starting to do testing and see what i can learn about it.

i want to add on a test with compost mixed soil with rich biology, then see if the biological one can handle higher amounts of urea before the plant are damaged. and hopefully at one point ill figure something out.

I fully support your experiment and look forward to your results. Mine was a cautionary tale for newcomers that don't have your experience and may feel overwhelmed and not know what to do or why if the worst happens. They may not be able to identify the cause. Was it soil, light, fertilizer, etc. I try to take out the variables for a new guy. A veteran is better equipped to know what is going on after some experience under their belt.

If you are interested here are some organic recommendations from NCSU.
Greenhouse

Nitrogen Fertility Management in Organic Tobacco Greenhouse Production | NC State Extension Publications

This publication provides recommendations for managing essential nutrient concentrations when growing organic tobacco in greenhouses using a float system.

content.ces.ncsu.edu

Field

Nitrogen Fertility Management in Organic Tobacco Field Production | NC State Extension Publications

This publication provides recommendations for managing essential nutrient concentrations when growing organic tobacco in the field.

content.ces.ncsu.edu

 

[billy]

i should have made it more clear that its only testing and not recomending urea but i cant edit no more. if you can add a first line that says it thats fine.
but i just have issue with myself that urea is sort of a boogey man, and i cant figure out why because anyone big enough to do research is doing hydroponics. so im resorting to garage science and i started 4 more packs of havana and ill test different scenarios and kill some plants so others dont have to

 

[deluxestogie]

Some years back, a rather well know FTT forum member and fully experienced grower of acre-quantities of tobacco killed all of his seedlings one season. This was attributed to urea in the fertilizer.

University Ag Extension Services in a number of tobacco states engage in extensive research not involving hydroponics. They regularly publish their recommendations to tobacco growers.

Bob

 

[Oldfella]

@billy, Out of idle curiosity I just Googled "urea fertilizer for tobacco ", Interesting results it may be that you do the same. It may help you with your experiment, after all research is the important part of any experiment. Good luck with it and I'll be watching with interest.
Oldfella

 

[billy]

stuff i find is saying it doesent work is in scenarios when they are intentionally having the least biology possible in the growing media.
if thats the case i should be able to replicate that failure easily.
ill add a test with pressure cooked media and boiled water so its extra dead, and compare that with a very biological media and observe any difference in urea tolerance. the current test is peat that been sitting dry in a bag for a year and my tap water which is filtered spring water so its probably not super sterile.

my only worry is that i will fail at failing, if i cant manage to kill a plant with a reasonable level of wrong fertilizer its gonna be hard to prove anything

 

[deluxestogie]

Don't fall into the trap of believing your results, when they can hardly be statistically significant with such tiny numbers and inconsistent plant variety.

I had this one plant that I sang to only with pop ballads. The other plant got to listen to only Italian grand opera. Operatic plants grow better.

Bob

 

[billy]

im aware anything i do isnt proper science, but i wanna do what i can to test and learn things. anyone can follow a recommended plan and get results, which is great,
but you can learn much more when intentionally trying different things and failing.
all i want from the singles at various dosages is to give me some idea of what the boundaries are, since right now i dont have much idea if they will all die or all be green and big in a week. then by that time bunch of Havana's will be sprouted and i can focus closer to the right area. then if i still didnt find anything usefull i got plenty of seeds and fertilizer for a step 3. but one way or another i want to try and help figure out why common fertilizer kills some peoples plants and not others.

 

[billy]

So normal disclaimer, this is only for testing purposes, plants are intended to die in the process. if you want safer options use urea free or organic and follow directions

were at 1 week mark and have some size differences in the first part, and havana sprouts are up for the next round of testing shortly.



so unable to find any negative effects so far, gonna have to try harder. these are 22 days from seed, transplanted and fertilized 7 days ago and re moistened with water once. conditions details in post 1 if needed.
fairly expected somewhat linear results. the water only "0" is doing pretty much nothing it managed to stretch 50% wider in the past 7 days. they get bigger from there, the 1x is outlier but it was noticeably fastest since before the test so it dont mean much. largest growth is organic which measures about 4x wider in 7 days. ill keep these going fertilized once per week to see if anything changes but onward to the next part with more accurate testing.


havana seeds after 1 week at 78f all from the same bagged seed head, so in the next part ill transplant these into 6 packs of 6. comparing 3 packs extra sterile at different strengths to 3 packs at the same 3 strengths but extra not sterile. so it will be like following

6 pack 1: pressure cooked peat based media. transplant washed off in sterile boiled water, given 1x strength tomato food (1 tbsp per gallon) mixed in sterile water in new 6 pack. should serve the purpose of more sterile than anything that would be done by accident.
6 pack 2: same but 2x strength
6 pack 3: same but 3x strength
6 pack 4: same as pack 1 but include compost that been outside for years and some water ran through different garden soil samples, so should have biology galore
6 pack 5: same as pack 2 but with all the biology
6 pack 6: same as pack 3 but with all the biology

and ive decided instead of increasing the strength of tomato food to 2x or 3x ill keep them all at 1x and use math and a scale to add the equivalent amount of urea that a 2x dose would have ect. i have a scale with resolution of about 0.0002 ounces which is obviously plenty to do that accurately. but that way im only testing 1 variable increasing in 2 opposite scenarios.

 

[deluxestogie]

Can I assume that these new six 6-packs will not be sharing water at the bottom of the same tray?

Bob

 

[billy]

ya im not doing bottom water for any of this, for fertilized water i slowly add drops in individual cells away from trays till it reaches the bottom, and starting with equally moist soil so it absorbs properly and similar amounts. then mid week re moisten with water same but make sure it only soaks to the bottom but not running out nutrients. then only ever sitting in dry trays so theres no leaching or cross contamination. ill do the next ones in tray carrier instead of a tray so there is no bottom anyway

 

[deluxestogie]

This is like peer-reviewed research, before you even undertake the study. Sorry to be a pain in the butt. I really would like to understand your final outcome. I've never had the patience to study this issue analytically.

Bob

 

[billy]

back to my garage science plant torturing adventures.

basically did what i said id do and waited long enough for decent amount of growth difference.
but to recap, since the only reasons im aware of as to why common fertilizer may be bad for tobacco seedlings is amount of urea and lack of biology to interreact with such urea, i designed the test around those 2 things. where i fertilize once a week with miracle grow tomato food 18-18-21 which is mostly urea based nitrogen. i did 1, 2 and 3 TBSP per gallon except 2 and 3 are just urea added to be the equivelant of that strength so only thing changed is urea content. and then compared each on abnormally sterile conditions VS with some compost and biology from outdoors added which ill call organic vs sterile medium.

plants were havanas form the same bagged seed head at only 8 days old, and any larger or smaller than average in either width or root length were discarded so thats the most uniform plants for a test i can do, they were all very near 3/10 inch wingspan to start and washed with sterile water before transplanting

making conditions as sterile as possible was no fun. had to pressure cook peat and perlite for 6 hours. boiled many gallons of water in big stainless pots and let em cool with the lid on to get sterile water to use for washing things in antibacterial soap and water for the plants. dont wanna make a big list of every detail but it was pretty much an all day project to do everything as sterile as i can

so were at 12 days of growth since transplanting, meaning they got fertilized on day 1 and 8, and given drops of sterile water in between feedings to maintain all with pretty even moisture. and they were centered under a quality grow light with airflow and they were on a mesh bottom tray carrier so any drips of water dont cross contaminate below.



not sure what i was expecting but didn't think results would just switch to down slope like a bell curve as you go to more ridiculous levels of urea. cause 3x urea is actually most similar to my 0 nutrients water only control, except more green color. which is odd to me, i didn't think the most opposite extremes would have the most similar growth

one in each of the 3's are still original size but i take blame for that since those 2 wilted once when i was letting the surface dry and didnt recover much. but otherwise even 3x full size plant strength urea on a tiny tobacco i would have no way of saying is bad apart from having direct growth rate comparisons. so if its possible to kill a seedling with urea in close to reasonable circumstances in potted plants i still have no clue how to replicate it

so all i really learned is having some compost and biology is largely beneficial to growth. in the 1x strength category, size increase was doubled by not being sterile and plain. from this i cant say how much was from additional micronutrients in compost or from biology helping. but if your adding outdoor compost to a plain medium you get both at the same time anyway.

ill go longer to see if it changes after being fertilized more times. but this is pretty much my waving the white flag. i dont know how to make a seedling die from urea. anything with even less bacteria shouldn't happen by accident in someone's home potted plants. and anything over 3x urea isnt reasonable considering most people probably give .25 strength to that small of a plant which is 12 times less

so take from that what you will. I'm going to keep using added compost and organic fertilizer like i usually do.

 

[landrace]

Cool to see how important the microbiome of the soil is. Thanks for sharing your work.

 

[ChinaVoodoo]

Why did you pressure cook for 6 hours? Wouldn't 30 minutes be enough? Perhaps other changes which would happen to soil after 6 hours are responsible for the sterile poor growth, such as alterations to the existing molecules containing carbon and nitrogen.

 

[billy]

i figured if i did that the first comment would be the middle of the jar might not have gotten fully sterilized. so not sure how to win that one. even if i re did a short time and it grew more i have no way to say whether its from not getting fully sterile or from cooking damaging the peat less. so i errored on the side of extra sure its sterile since im unaware of anything peat does other than being a fluffy thing for the most part.

 

[ChinaVoodoo]

i figured if i did that the first comment would be the middle of the jar might not have gotten fully sterilized. so not sure how to win that one. even if i re did a short time and it grew more i have no way to say whether its from not getting fully sterile or from cooking damaging the peat less. so i errored on the side of extra sure its sterile since im unaware of anything peat does other than being a fluffy thing for the most part.

I don't blame the extra precaution. The question of why not is a valid one. I tend to lean towards the original conclusions, and I applaud you for the work you put into this interesting experiment. But if there's a next time, I would try again for 30 or max 45 minutes in order to rule out a confound. Or treating it all for over an hour, then figuring out how to inoculate one half.

I'm confident with 30-45 minutes enough to depend on it for unsalted meat, so I think it's good enough for soil.

Millard reactions happen at pressure cooker temperatures, (see the cavendish threads) and they're proven to alter carbohydrates and proteins. We know carbon matters. It's above my head as to why. I just think it's worth looking into.

 

[deluxestogie]

Excellent demonstration. I would say that a doubled "wingspan" is more like a quadrupled leaf surface area (or mass). The overcooked (?Cavendished) soil question raised by @ChinaVoodoo is a valid point that would require detailed biochemical analysis to clarify. (Anybody out there looking for a PhD thesis project?)

In the world of medicine, where dosage errors are common and often well investigated in retrospect, the errors tend to occur in the calculation of dilution: how much diluent to add to a specified amount of a concentrated compound. And these errors, though mostly categorized as half as much or twice as much diluent (say, sterile saline solution added to a vial of freeze-dried vaccine) as required, are related to the units of measure. In the decimal world, errors of powers of ten happen with alarming frequency. [Simple remedy: have a second set of eyes look at the dose, before you give it.]

What does that mean with regard to urea on seedlings? When recommended application rates are (as is common) specified in pounds or tons per acre, then you have to figure out a dose for your tiny garden bed or your 1020 tray. It would not be difficult to accidentally dose your plants with clumsy math, killing them with osmotic shock alone—essentially pickling the roots. My suspicion all along has been that this explains the urea worry on baby seedlings.

[Decades ago, there was widespread, public horror at a study that demonstrated the consumption of monosodium glutamate (MSG, aka Accent) caused brain lesions in laboratory monkeys. It turned out that the experiment used such an enormous concentration of dietary MSG (something like 100 times what you would sprinkle on your food) that it caused sudden shriveling (dehydration) of brain tissue, which in turn caused the brain lesions. Pickled monkey brain! It was like packing cabbage with salt, to make kraut.]

Bob