nitrogen levels in fertilisers

[hugh grant]

hi
i wanted to know what is considered a high nitrogen level as compared to a low nitrogen level as stated on fertilisers?
thanks for any help.

hugh

[shibui]

Not sure what your question is abut, Hugh?
Look at the NPK numbers on the pack. The first of them is the % nitrogen in the fertiliser. The lower the number the less N. The higher the number the higher the proportion of N.
High nitrogen probably means a higher proportion in relation to the P and K rather than an absolute number because the amount of N the plant gets will also depend on the concentration used and how much is applied. some ferts with higher N numbers recommend weaker application rates so actually give less N than another fert with a lower N number - does that make sense?
Low N ferts will have a N number of 0-3. The highest you will find will be about 20, possibly as high as 30. Urea would be the most concentrated N fert but not sure what the N ratio is. It does have to be used carefully though to avoid death by overdose. The larger the numbers the more careful you will need to be to follow the instructions.

[Chris Sirre]

Hi Hugh,

Shibui is absolutely right there.
About Urea in fertilizer it's available at least as high as 82 in de form of Anhydrous Ammonia in synthetic fertilizers. The NPK ratio for Urea as a synthetic fertilizer is 45-00-00

Cheers,
Chris

[Jamie]

gday

cant say much more than shibui and chris but..

I did a test a couple years back using urea I think the npk was 49-0-0. I figured that this stuff was going to blow the head off what I put it on but was somewhat surprised. I used four figs bought from out the back of a local nursery (just a section for stock that wasnt likely to sell, picked them up cheap but thats another story!).

anyways, here is what I did-


Fig 1- I used the Urea by itself, watering as per usual

fig 2 - my normal fert regime which is a liquid fert like miracle grow every five days, seasol every two days after that, a slow release pellet applied as per directions. water as per usual.

fig 3 - slow release and seasol. water as per usual

fig 4 - no fert what so ever. water as per usual.

short term results -

fig 1 - extremely strong growth, long internodes, lots of green growth. 2 foot of extension growth over a 3 month period in the growing season. les useful branching. more green growth then woody.

fig 2 - strong growth, better internodes, lots of green growth with more branching that would be useful. woody branching ready for wiring

fig 3- strong growth, similar results to fig 2. not as woody branching. not as long extension.

fig 4 - growth good, smaller leaves.

these results were pretty much expected. the following was more surprising though.

fig 3 - eventually died.

fig 4 - eventually died.

fig 2 - growth good and eventually styled

fig 1 - growth continued to be strong, eventually styled. no obvious ill effects from the urea use. lots of strong growth

unfortunately the testing wasnt able to continue as these four I ended up losing through the floods. I beleive the urea can be used if watched carefully and applied using exact direction. I beleive if urea was used in ground growing stock at the right time of the year (growing period) it would definately be an acceptable fertiliser. but really I think just as good results can be acheived through normal fertilising routines and it is a lot safer, gives better results as internodes and branching is more useful.

the balance of ferts in fertilisers is there for a reason, it gives a balance of what a tree needs, there is not point in getting masses of growth that take a long time to harden off as green shoots can be problematic, wiring can be touch and go as some will die off, where as a semi woody to woody branch is more likely to not die of from cambiums breaking.
the nutrients in fertilisers are there for a reason and all do a certain job, putting out strong new growth, good colour in the leaves (which can help with photosynthesis, as some of you may know a varigated leaf form doesnt photosynthesise as well as only the green section has the ability to do this). nutrients that make for woody growth, help with thickening and nutrient transefer etc.

balanced ferts are definately the way to go, using a fertiliser that is much higher in one aspect than the other does have its uses though. the thing to remember if there is an over abundance of one nutrient it can also stop other nutrients from being taken in.


(if any of the info is wrong please feel free to correct it )

jamie

[hugh grant]

THANKS HEAPS GUYS.

Shibui what im trying to get at here is to find out what is a higher nitrogen fertiliser which would be good for strong growth when training trees and growing on trees. and also what is a lower nitrogen level fertiliser to use for less rapid growth for more styled trees that just need maintaining. i haven't been the best at fertilising in the past few years as i was rather lazy and didnt put in the time to fertilise properly and since have had a few ill effects from some of my trees as they have not been fertilised properly. I really want to give my trees the best possible feeding regime starting this coming season. And since im starting to use substrates this season like diatomite i think i need to start fertilising better.

Look at the NPK numbers on the pack. The first of them is the % nitrogen in the fertiliser. The lower the number the less N. The higher the number the higher the proportion of N.
High nitrogen probably means a higher proportion in relation to the P and K rather than an absolute number because the amount of N the plant gets will also depend on the concentration used and how much is applied. some ferts with higher N numbers recommend weaker application rates so actually give less N than another fert with a lower N number - does that make sense?

Thanks Shibui, Yes that certainly does make sense, i understand what your saying.
So in that case would it be better to regularly fertilise with a fertiliser with an average nitrogen level rather than a high nitrogen fert?

So if urea is an NPK of 45-00-00 like chris said than what would be a good but lesser NPK?

these results were pretty much expected. the following was more surprising though.

fig 3 - eventually died.

fig 4 - eventually died.

fig 2 - growth good and eventually styled

fig 1 - growth continued to be strong, eventually styled. no obvious ill effects from the urea use. lots of strong growth

Thanks heaps for all that info Jamie, much appreciated.
These are very interesting results and show a lot for how a fig can be heavily fertilised but not so much way under fertilised. what growing medium did you use for these trees?, was it soil or a substrate?

Im finding this very interesting and helpfull, thanks Again.

Hugh

[Jamie]

no probs champ,

mate I was using diatomite for all of them. these results are from my experience doing this. im sure they are way more accurate ways of testing these things, actually I am positive there is a thread on here by Grant bowie and Leigh in relation to growing mediums and fertilising.

I did wish that they didnt die, they were going to be interesting trees eventually. I even had a crack at grafting which had taken but those blasted floods

[63pmp]

Pot trials are the best way to judge how a fertiliser will work with a particular plant and potting mix. Good work Jamie.

Urea is not a great N source for pots, as it is not taken up by plants very well in that form. Urea has to be taken up by bacteria in the potting mix and then converted to usable nitrogen forms before a plant can take in that nitrogen. Nitrate nitrogen, or ammonium nitrogen are the preferred forms of nitrogen.

The term "balance" is a poor one, simply because each plant has its own particular balance of elements for optimum growth which varies on a day to day basis depending on temperature, light conditions, transpiration rate, flowering, fruiting etc. No one knows what these elemental concentrations are, so a "balanced fertilizer" is a furphy. The other thing is that fertiliser bought at the hardware are simply a mix of chemicals and are predominantly designed for soils, not potting mixes. Soils generally have a high reserve of elements, though Nitrogen leaches away easily, potassium is taken up by plants in high concentration, while phosphorous becomes bound up to soil particles, these elements often become limiting in soil, hence the importance of these components in fertilisers. In potting media, nearly all elements needed for growth are absent, these means that feriliser for bonsai is more complicated than what is commonly available.

Fact is, plants are faily tolerant of varying elemental concentrations, as seen by the number of hydroponics mixes that all work, the most important point for good growth and plant health is that ALL elements required for growth are be present.

Nitrogen gets a lot of press but is not necessarily the most important component in a bonsai fertiliser. Plants will only grow to the limiting element, that element which is deficient in the fertiliser program. Since most prepared fertilisers are low in magnesium, calcium and sulphur, these are usually the limiting elements in any fertiliser bought from a hardware.

Mostly, Calcium, is limiting in bonsai culture, this element is only taken up by the growing tips of roots, trees have a hard time getting it out of potting mixes. Some literature says that calcium levels need to be a high as nitrate levels for good plant growth. This is a contentious point in bonsai fertilising because some big names in bonsai, who irrigate with high calcium contianing waters (hard water), say it is not necessary. But any study of fertilising potted palnts practices will show that if you have soft water, or water with low salts, like Sydney tap water, the opposite is true. Calcium is absent from just about all hardwae bought fertilisers.

The NPK and other elemental content levels should be used to calculate actual solution concentrations by weighing or measuring the fertiliser being applied to the plant. You can then work out what elements are missing from your fertiliser and put together a fert that is at least complete.

Paul

[shibui]

So in that case would it be better to regularly fertilise with a fertiliser with an average nitrogen level rather than a high nitrogen fert?

I believe that it is better to use a range of fertilisers rather than just one. As Paul points out plants need much more than just NPK so using a range will help to supply missing elements. As soil less mixes have become more popular the manufacturers have recognised the deficiencies and many modern ferts now specify +TE (with trace elements) to supply the extra elements that plants need.

You can certainly get good growth using a higher N fert (with TE) but use other brands, combinations to overcome any deficiencies in any one alone.
In my shed there is Osmocote slow release (15:3.5:9.1+TE fairly high N), Osmocote water soluble (28:1:14+TE high N),Charlie Carp (9:2:? label has faded), Thrive soluble for flower and fruit ( 15:4:26 +someTE note that the N figure is same as osmocote but this is regarded as high K fert because its about RATIOS), Organic life pellets (4:3:2 this one is composted manures, fish, seaweed and Blood and bone - not really high in N,P or K but slow release because it uses organic bases and the seaweed means it should have every trace element known and a few more besides.), Blood and bone. Also use liquid manure and worm juice every few weeks during the growing season. So you can see that I use a wide range in an attempt to give the plants the full range of nutrients they need. I figure that if the elements are present the plants will take what they need and leave what is not needed at the time.

Grant's tests with fertilisers showed that a combination of Osmocote slow release and additional soluble fert gave better results than either alone. I would add an occasional dose of seaweed as well - the ocean has all the elements that have been leached out of the land over millions of years. Seaweed extracts these elements from the water so when we use a seaweed fert (soil conditioner) we are providing all? trace elements.

The 'limiting factor' theory is pertinant to bonsai. Doesn't matter how much N you put on if the plant has too little water. ALL factors must be supplied in the correct balance to get good growth. Fortunately most plants have a wide range of tolerance for most elements and will survive despite what we do to them.

I'm not sure why Jamies figs died but I wouldn't put it purely down to the fert regime without further testing. I have seen figs that have survived for years in bonsai pots without ANY fertiliser at all! but they do really respond to heavy feeding.

[Bretts]

Grant's tests with fertilisers showed that a combination of Osmocote slow release and additional soluble fert gave better results than either alone.

Not doubting anything you say here Shibui but I think ya gota remember to think outside the square. There is nothing in this that suggests that simply adding more osmocote or more liquid fert on their own would not have improved the results as well
Simply more fert=better growth.

[hugh grant]

Jamie was it straight diatomite?

So to get the best growth and maintain good health you really need a good range and balance of all elements to give you best results. If im using a range of all different fertilisers like Shibui is then you will get more of the elements overall from using all different ones then just your NPK which is more beneficial to the plant.

If im using a substrate then im guessing you will have to fertilise a lot more often?

All this information is very useful and very informative.

Thanks,
Hugh

[Jamie]

gday crew

thanks heaps paul, your knowledge on this stuff is a great asset to the site and is extremely helpful!

as you say balance probably isnt the right term to use, and you have explained it pretty well. the need for trace elements is definately a key aswell as like I said before I beleive if certain elements/nutrients are missing or are of higher values then others then the others intake isnt going to happen? (thats how I understand it anyways). I forgot to add I do use a trace element additive to help this along. the stuff I am using states it only needs a 6 monthly application but I do it a little more frequently than that, more like 2-3 month.

as for why the figs died as you said it cant be sure about the ferts, there definately could be other reasons, I just didnt notice any thing that could of done it as they were pest and disease free (I have been really lucky in that sense where I have had minimal disease or pest problems, only ever lost a couple of trees to pest which was some older juni I had that got smashed by spider mite which was my fault as I didnt pay close enough attention to the thick foliage pads as it all looked healthy then in a few weeks things went down hill. it could of been longer with the way juni are too).
I think the biggest reason for the loss was flooding, I lot a lot of trees due to how wet it got up here and I couldnt do much about it as I didnt have the bench space for 200 odd grow on trees, they were all on the ground and were in a few inches of water for a fair while.

hugh

I do beleive it was a mix of diatomite, zeolite and organic. in that order di. - 25% zeo. - 25% org. - 50%

that was when I first heard bout diatomite and only had a couple of bags of it.

jamie

[hugh grant]

Ah ok jamie thanks, i just repotted a few tridents into 100% diatomite so ill see how they go

Hugh

[Jamie]

Ah ok jamie thanks, i just repotted a few tridents into 100% diatomite so ill see how they go

Hugh

no probs! I use 100 percent aswell, and recycle it to, generally when recycled it gets mixed with some organic and zeolite. trident in 100% should be fine, just be a little careful when it gets hot as it is going to dry out resonably quickly. some of the figs and clero during the really hot days needed at least two waterings.

jamie

[hugh grant]

og good im glad to hear someone else using straight diatomite as i havnt really heard anyone else doing it. yeah i suspected that id have to water quite a bit more. at the moment ive been watering the tridents once a day but in summer i may need 2 or 3 waters esspecially during january and febuary around here.

Hugh

[63pmp]

Hi Jamie,

plants sitting in a couple of inches of water for a while (greater than 2-3 days) would probabaly do it. Were they in the flood waters themselves or just accumulated rain in the back yard? As flood waters carry all sorts of pathogens, plant and animal. So waterlogging is not good, but pathogens finish them off. I had a lot of trouble with dying japanese maples one year, the pots were sitting on a large tile, after much scratching of the head I saw that surface tension kept a couple of mm of water in the bottom of the pots, once I lifted the pots onto thin strips of wood for support they improved, my point is it doesn't take much depth of water to kill a plant.

I used to use a mix of fertilisers, but the cost was getting me down. So I made the move to pure mineral fertilisers. I don't have a problem with mixing up fertilisers, though I think a lot of nutrients are wasted. After much reading and research I felt that a one hit liquid feed with everything, all 12 or so elements, in specific concentrations, was the way to go. I now make up 1000L batches of fert and it only costs me a couple of dollars. Every thing is measured and controlled, It's been a steep learning curve but I think I'm getting good growth, and much healthier plants, now, compared to what I was getting with mixing up brand names.

I always have trace elements in my fertiliser mix, for a couple of reasons. One is plants need them when they do, and its impossible to know when they need them. If they are growing strongly and you want shoot extension to thicken trunks then they need them now, If they are finished trees, then the may not need them, but it doesn't hurt them to be there. The other reason is that my potting mix is 1/3 zeolite, and it sucks trace elements out of solution and holds onto them tightly. So if only applying traces occassionally to zeolite mixes, then there is a very high chance the plants will be deficient. My routine now is to fertilize for 3 days, and then flush on the fourth.

I found that the trace elements supplied from yates are in the wrong concentrations. I don't remember which, but I think copper was dangerously high, and another was too low. Remember, these fertilisers were intended for soils, not potting mixes.

Paul