Am I using too much nitrogen?

[Errol]

I grow a number of plants (tomatoes, cucumbers, capsicum, strawberries, beans, leeks, beetroot and even carrots) in laundry buckets, in the same recirculating greenhouse hydroponic system. The pre-mixed dry nutrient I use is Peters Professional Hydrosol, containing 6N+36P+18K+3Mg and I've also been adding an equal quantity of calcium nitrate (19.6N+15.5Ca) plus a little Fe. I run with an EC reading of 2.0 which keeps the plants generally happy, although the tomato buckets do get an occasional individual nutrient bonus of 3.0 closer to picking time. The local water supply has a ph of around 7.0 which the plants seem to handle well enough (maybe I should adjust this?). You can probably tell from all this that I'm not an 'exact' hydroponic gardener and that I try to grow a range of plants using a 'median' EC and ph.

I've generally achieved quite acceptable results for some seven years now, but one problem needs fixing - the plants produce too much growth and have large root systems. Strawberries in particular are far too leafy, resulting in aphid, then wasp invasions later in the season.

I'm thinking of cutting back the nitrogen to moderate excessive vegetative growth. Can readers suggest whether I'm on the right track or just heading for trouble? Any advice on plant nutrition would be welcome. Thanks.

[Errol]

Sorry, for Hydrosol read 6N+18P+36K+3Mg

[Luches]

Hi Errol,

I am pretty familiar with these kind of maths and procedures as I used to help out a chap with a similar way of making nutes. As for me, I am actually calculating and mixing my own formulas from scratch (raw materials only).

What you are planning is a bit tricky, as you have to settle for actual NPK, (6N+18P+36K+3Mg aren't actual or elemental, but conventional NPK). And you should preferably use (convert all to) PPM as a common unit for all ingredients. I'll take care of that actually, but you'll have to cope with it
If this isn't done properly, all maths tend to be false, - as you try to mix "apples and pears".

If you agree with this role and confirm, I'll try to get it right for you. I am asking for confirmation because unfortunately, I've had some cases lately when people got overwhelmed by the maths or didn't get back to the topic for some unknown reasons. I did all the writing and work for nothing...

Thanks for the understanding!

Cheers,

Luches

[Errol]

Hi Luches,

Thanks for your response. I'm more than happy for you to do some calcs, but I wouldn't want you to spend a lot of trouble on complex formulae or anything since I'm not over keen to buy and mix my own ingredients. One of the reasons I like Hydrosol is because it's already pre mixed! I had wondered about maybe just reducing the calcium nitrate quantity. I'd be glad to hear what you have to say though.

Cheers.

[Luches]

Hi again!

Originally Posted by Errol

I'm more than happy for you to do some calcs, but I wouldn't want you to spend a lot of trouble on complex formulae or anything since I'm not...

Sounds like an agreement to me

Originally Posted by Errol

I had wondered about maybe just reducing the calcium nitrate quantity. I'd be glad to hear what you have to say though.

Well, I was actually talking about modifying (adjusting) your Hydrosol by adding THE RIGHT (adequate) quantity of calcium nitrate and perhaps talk you nicely into adding one more component.
That is what I was talking about when I narrated about helping out a chap who did the same and wasn't sure what the actual outcome was.

To be sure what you have got, and how much calcium nitrate to add, I need to decompose Hydrosol and put it in my spreadsheet.

You'll have the results tomorrow.

One more question here: have you got 3% of actual Mg in Hydrosol or does it say 3 Mg0? And, I suppose there is no Cl at all, as it is a mono-mix?

Later,
Luches

Edit: are you sure about the N and Ca content of the Calcium Nitrate you use. Commercial fertilizer grade Calcium Nitrate (with a purity of 98-99%) actually has 15.6% of N and 18.5% of Ca. It's not that much of a difference, but we want to get it right, - don't we? ;-)

[Errol]

It comes from relying on a dubious memory after kneeling in a dark shed peering at fertiliser formulae, but you're dead right - the correct calcium nitrate mix is nitrate nitrogen 14.5% + ammonium nitrogen 1.0% for a total N of 15.5%. For the calcium, expressed as elemental it is 19.6% and expressed as CaO it's 27.5%. All this according to the bag label and so cleverly transposed by me in my earlier post!

And you're right about the Mg in the Hydrosol too. The mix is:

nitrate nitrogen 6%
phosphorous pentoxide 18%
potassium oxide 36%
magnesium oxide 3%
Trace elements are B, Cu, Fe, Mn, Mo and Zn. No Cl mentioned though.

Hope this helps and thanks for your assistance. I'm more than happy to add one more component, by the way!

Cheers,

Errol

[Luches]

Nice work!
I wasn't exaggerating when I told you that it was kinda tricky... wasn't I?
You'll see it will get even more odd, before we got it finally nailed

Nothing to worry about though, your part is as good as done until I've figured out the final formula and mix.

Later,

Luches

[Luches]

Here you go Errol!

It may look a bit complicated at the first glance, - but it's simple assuming that you anyway mix 0.Xgr/Liter to get your mix. Have a look at it first and tell me if you need supplementary explanations, perhaps different variations, concentrations or mixes (higher total PPM, higher N-content), etc.



PS: to complement Ca up to 180 PPM standard (only in case your tap water is soft and has little Ca, otherwise it may provide 25-50 or more PPM of Ca already): Calcium Chloride - CaCl (ferilizer grade) gives at 0.1gr/liter 28 PPM of Ca - BUT also 64 PPM chloride (1gr/l = 280/640). To be used moderately anyway - especially if your tap water is already rich in chloridel!

Important: NEVER mix calcium nitrate or calcium chloride (salt or concentrate) with magnesium sulphate or Hydrosol (salt or concentrate)!!! It will lead to a chemical reaction and make the whole batch unusable. In case you want to mix concentrate, make two components: A: calcium nitrate + calcium chloride and B: Hydrosol + Magnesium Sulphate. If sufficiently diluted with water as in the nutrient solution, there is no problem at all.

Cheers,
Luches

[Errol]

Hi Luches, thanks for doing your calcs so quickly. If I'm reading them correctly, it seems that you think the mix could certainly do with some magnesium sulphate - and that the concentration should be 7gms/litre Hydrosol, 7gm/litre calcium nitrate, 4gms/litre MgSO4 and possibly 1 gm/litre of calcium chloride? Am I close or on the wrong tram altogether? Our tap water is soft and not heavily chlorinated, by the way.

Wouldn't that imply that aside from adding a sizeable amount of MgSO4 and a little CaCl2 to my nutrient, I would keep on doing what I am now ie using equal quantities of Hydrosol and calcium nitrate?

This would be at odds with my thinking at the moment ie that the level of N in the 50/50 mix is possibly too high, causing too much vegetative growth.

What are your thoughts on mixes referred to in the following link?

MIXHYDRONUTRIENTS

Many thanks again for your efforts and interest.

Cheers,

Errol

[Luches]

Hi again - you're welcome!

Originally Posted by Errol

If I'm reading them correctly, it seems that you think the mix could certainly do with some magnesium sulphate - and that the concentration should be 7gms/litre Hydrosol, 7gm/litre calcium nitrate, 4gms/litre MgSO4 and possibly 1 gm/litre of calcium chloride? Am I close or on the wrong tram altogether?

Well, I bet you got confused with the decimals. It's 0.7 (zero point seven) gram per liter (litre), 0.7 and 0.4 Mg. (obviously only 0.1g CaCl/liter)
Attention: 7 gram per liter of both would probably kill your plants over night.

Originally Posted by Errol

I would keep on doing what I am now ie using equal quantities of Hydrosol and calcium nitrate?

Indeed equal quantities of both in the present example of a mix.

Originally Posted by Errol

This would be at odds with my thinking at the moment ie that the level of N in the 50/50 mix is possibly too high, causing too much vegetative growth.

But equal quantities only determines the proportion of N vs. P and K, it doesn't say if the N-content is too high or not. It actually depends on how much Calcium Nitrate is used per Liter. I bet you were using more than 0.7 g/l, were you...?

Originally Posted by Errol

What are your thoughts on mixes referred to in the following link?

Well, well.... I haven't read them trough and had no time to check on them in detail, but I've found some things I'd not necessarily agree with straight away. They seem to lean on Dr. Resh a lot and (all due respect) he is going pretty heavy duty (avoiding to say aggressive) on feeding. On the other hand, they are playing "cheap" with Mg and Sulfur. While the standard content of Mg is around 50, and if using Magnesium sulfate, Sulfur should- actually will be around 80 PPM anyway. Which is just fine because most plants require that much of later elements. Dr. Cooper and Hoagland formulas are indeed the basics of all formulas, but also dinosaurs and perhaps a little outdated. But then again it's damn hard to find good and reliable sources for nutrient formulas that are up to date.

If I understood your goal and concept right, you are growing various plants and not mainly leafy vegetables. In that case I recommend a N-content not exceeding 150-170 PPM of N. Lettuce would be happier with some 200-220 PPM, but tomatoes, peppers (as well as cucumbers) and most nightshade wouldn't really like that.

210 PPM of K as an outcome in my example is not really high (not good enough actually), - for tomatoes 280 and plus would be better. But with Hydrosol there are clear limits of increasing K content, without exceeding P limits (50-60 PPM). Well here one could push a little and increase to 0.8-0.9 gram/liter of Hydrosol without doing amy harm. Even somewhat further if more K is badly required (high yield of tomatoes, capsicum).

PS: the problem with Calcium Nitrate is generally that you need to add sufficiently to cover Ca needs (140-180 PPM), and obviously go too high with N. With a small part of CaCl you can cover Calcium needs, without exceeding N-content.

Hope all this is intelligible and helpful.

Cheers,
Luches

[Errol]

Well, I bet you got confused with the decimals. It's 0.7 (zero point seven) gram per liter (litre), 0.7 and 0.4 Mg. (obviously only 0.1g CaCl/liter)
Attention: 7 gram per liter of both would probably kill your plants over night.

Apologies for the mathematical aberration - I get confused by the ',' you use as a decimal point - a European practice I think? I'm from Australia where we use a '.' to denote the decimal point. Yes, 7gms/litre would probably even kill you and me off overnight!

But equal quantities only determines the proportion of N vs. P and K, it doesn't say if the N-content is too high or not. It actually depends on how much Calcium Nitrate is used per Liter. I bet you were using more than 0.7 g/l, were you...?

Actually I work off the EC reading. I toss in enough Hydrosol and calcium nitrate to get a reading of about 2.0. I have two 160 litre tanks (connected) and I make sure I introduce the Hydrosol and calcium nitrate at opposite ends of the tank to make sure there's no harmful chemical reaction. But with some MGSO4 and calcium chloride in the mix as well, that would mean the salt level would actually produce an EC reading of 2.0 with a lower quantity of calcium nitrate and therefore a lower nitrogen content? This would mean less vegetative growth and could solve the problem?

If I understood your goal and concept right, you are growing various plants and not mainly leafy vegetables. In that case I recommend a N-content not exceeding 150-170 PPM of N. Lettuce would be happier with some 200-220 PPM, but tomatoes, peppers (as well as cucumbers) and most nightshade wouldn't really like that.

As I read your New Mix 2 formula, it already contains 151.2ppm of N, so the mix you suggest of 0.7gs/l should work well with my non-leafy plants?

I think you are gradually getting me very close to a solution here, Luches, complex formulae or not! Thanks for your patience.

Cheers,

Errol

[Errol]

More reflection.......Plan A is as follows:

8 parts Hydrosol (to get the K up a bit)
4 parts MgSO4

7 parts calcium nitrate
1 part calcium chloride

Mixed in those proportions, but keeping the concentrate separated, and added to my nutrient tanks until I reach an EC reading of 2.0.

Hopefully that will achieve a good result!

I do appreciate your work, patience and perseverance with somebody you don't know, probably on the other side of the world. If everybody was as generous with their time and as prepared to help other people as you are we wouldn't have the problems in the world that we do today.

Best wishes and many thanks again,

Errol

[Luches]

Next step...

1. Decimal problem solved. Actually my spreadsheet (MS) uses comma to express decimals, that's why I tend to use it too. But true, european practice is right too.

Originally Posted by Errol

Actually I work off the EC reading. I toss in enough Hydrosol and calcium nitrate to get a reading of about 2.0. I have two 160 litre tanks (connected) and I make sure I introduce the Hydrosol and calcium nitrate at opposite ends of the tank to make sure there's no harmful chemical reaction. But with some MGSO4 and calcium chloride in the mix as well, that would mean the salt level would actually produce an EC reading of 2.0 with a lower quantity of calcium nitrate and therefore a lower nitrogen content? This would mean less vegetative growth and could solve the problem?

Yes, adding more components will obviously lower the Nitrogen content with the same EC reading. And, your primary logic behind the way you proceed is right too. But....

Originally Posted by Errol

As I read your New Mix 2 formula, it already contains 151.2ppm of N, so the mix you suggest of 0.7gs/l should work well with my non-leafy plants?

Yes, except that the "New mix 2 formula" I gave you will not total 2.0 EC, but less. Even with the new ingredients, with 2.0 you'll probably end up with more than 150 PPM of Nitrogen. We have 2 ways of getting to finalize it here: 1. I'll calculate and tell you the almost exact EC needed to realize "New mix 2 formula" with the PPM content as shown, or I'll explain you why actual PPM of a formula and a EC reading are not the same cup of tea. You tell me!

Another even simpler way to get to this formula will be to weight of 210 gram of calcium nitrate, 210 gram of Hydrosol, 120 gram of magnesium sulfate, and 40 gram of CaCl. And do what you did with your tanks before, except that you fill in exactly 150 liter in each.

Originally Posted by Errol

I think you are gradually getting me very close to a solution here, Luches, complex formulae or not! Thanks for your patience.

I truly hope so, and don't worry - it took me some 2 years to see the whole plot behind formulas.

PS: you next post just dropped in now - will get back to it soon.

Cheers!

[Luches]

Next

Originally Posted by Errol

More reflection.......Plan A is as follows:
8 parts Hydrosol (to get the K up a bit)
4 parts MgSO4
7 parts calcium nitrate
1 part calcium chloride

Mixed in those proportions, but keeping the concentrate separated, and added to my nutrient tanks until I reach an EC reading of 2.0.

OK, I was about to make the proposal of adding just a pinch more Hydrosol to get the K up a bit (despite the fact that P will get somewhat high - which isn't an issue at all).

I was also wondering if you use to make concentrate anyway. If so, (which is actually smarter) the strategy to apply can be adopted accordingly. You anyway should take the lead on the method and the actual procedure, as you need to do that part regularly by yourself.

Still, the basic EC of 2.0 seems quite high to me, in general (for general purpose feeding) as well as according to the formula we are about to settle for. As explained earlier, it can be determined by adding relative conductivity of each ingredient. It's more accurate and it helps knowing what may be wrong (what should be changed) in case of trouble.

As for your setting up procedure (as usual), it doesn't change much - except that instead of adding equal parts of concentrate until getting to 2.0 mS (or EC) it may only be 1.7-1.9 (still to be determined).

Btw: I am actually not that far away from your place. Depending on your location in Australia, I'm about 3500-4500 roughly estimated miles direction North-northeast (S.E.A)

Cheers,
Luches

[Luches]

Here's the final proposal:
According to your "plan A" (slightly more CaCl)

8 parts Hydrosol (to get the K up a bit)
4 parts MgSO4·7H2O
7 parts calcium nitrate
1.5 parts calcium chloride

A. Hydrosol + MgSO4·7H2O
B. calcium nitrate + calcium chloride

In terms of PPM it looks like follows:


To end up with exactly this formula and actual PPM of each element, you need to add EQUALLY as much of A. and B. until you reach EC 1.8(4). Though you can anticipate what it will look like if you go with EC 2.0.

I have calculated (most accurately) what you have had previously, when mixing equal parts of Hydrosol and calcium nitrate until you reach EC 2.0:


PS: The maths and formulas behind the later scene are part of my professional secret, though. Yet, I can tell that I had to completely decompose Hydrosol into its basic components (they're actually kinda obvious regarding the formula). One has also to know the actual electrical conductivity of each single component, even of those that are used to manufacture Hydrosol.

I guess you can go solo from here... but in case you have further questions, do not hesitate to rattle my bamboo cage!

Cheers,
Luches

[Errol]

Still, the basic EC of 2.0 seems quite high to me, in general (for general purpose feeding)

I have a list of recommended ECs from my local hydroponic supplier which I've been using ie

Bean 2.0-4.0
Beetroot 1.8-5.0
Capsicum 1.8-2.2
Carrots 1.6-2.0
Cucumber 1.7-2.5
Leek 1.4-1.8
Strawberries 1.8-2.2
Tomatoes 2.0-5.0

They certainly vary, and that's the dilemma one has in trying to grow a number of crops in the one nutrient, of course. The supplier told me tomatoes should have a minimum EC of 3.0 if they were to have any taste, otherwise they'd be watery and tasteless. But I think he might know more about marijuana (that's what most of his customers grow!) - my tomatoes have always been quite tasty at 2.0.

The recommended pH for most of the plants I grow is closer to 6.0-6.5 than the 7.0 I usually run, so maybe I'd better get that down too.

Just one last thing before I leave you in peace, Luches, should there be a couple of formulae towards the end of your post that might not have copied in properly?

I'm from Hobart, Tasmania actually - where the temp is 10.8 at the moment (6.20pm). A bit cooler than your home territory I imagine. My wife and I have just returned from 8 days in Singapore where our daughter and family live. 30-32 degrees and sticky most of the time, hard to get used to.

Cheers,

Grant

[Errol]

OK, the formulae have now appeared!

[Luches]

Hi again Errol,
Sorry for the delay, but as I live in some sort of country under technological development, I had no internet connection for some 12 hours.

Originally Posted by Errol

I have a list of recommended ECs from my local hydroponic supplier which I've been using ie

Bean 2.0-4.0
Beetroot 1.8-5.0
Capsicum 1.8-2.2
Carrots 1.6-2.0
Cucumber 1.7-2.5
Leek 1.4-1.8
Strawberries 1.8-2.2
Tomatoes 2.0-5.0

According to my previous explanations, one could hopefully deduce that about plant nutrition, nutrient concentration, EC, PPM and such, there are several levels of understanding. Hence there are several levels of recommendations as well

On an advanced level the actual PPM of each element which is needed by a specific plant is considered firstly - total EC is secondary (and actually a result of the later data). When seen from such perspective, PPM (gram/liter) of each single raw materials used (not elements) will then result in a specific EC.

Hence, any EC recommendations (as in total concentration) for specific plants are actually pure nonsense - if not linked to a formula or a specific product. Without knowing the actual PPM content of each element of a nutrient, a recommendation of a EC could either be close enough or completely false.

It may help pointing someone into the right direction, you'd add? Well it may help, - but it may lead into erroneous reasoning and practise as well. Unfortunately lead to erroneous argumentation also

Originally Posted by Errol

The supplier told me tomatoes should have a minimum EC of 3.0 if they were to have any taste, otherwise they'd be watery and tasteless. But I think he might know more about marijuana (that's what most of his customers grow!) - my tomatoes have always been quite tasty at 2.0.

Rome to the Romans and tomatoes to the Neapolitans
I guess taste of tomatoes is linked (lets say) 80% to genetics. I'm growing a marble sized 'wild' indigenous tomato variety which beats Marianna's Piece, Oaxacan Jewel and even some russian specialties in flavor. Grown in earth it unfortunately tastes slightly bitter. But grown in Hydro (in actually quite low nutrient concentration) it is as rich in flavor as grown in dirt and notably less bitter.

Originally Posted by Errol

The recommended pH for most of the plants I grow is closer to 6.0-6.5 than the 7.0 I usually run, so maybe I'd better get that down too.

I STRONGLY recommend to get and keep PH between 6 and 6.5, otherwise you will run into iron deficiency, followed by (over 7) boron, coper zinc!

Just wait the PH reading of your new formula, it actually should get you a lower PH (at least somewhat).

PS: temperatures here have been around 30-33 since end of May, only a few days with heavy monsoon rains were cooler. Before (April and May) they were much higher... Though, November, December January and half of February, day temperatures range between 20-25° C and not a single raindrop for 3-4 month. Anyway, that means less than 3 months to grow ripe tomatoes from seed to ripe fruit outdoors! Same for capsicum and many others. 365 days a year top growing season

[Errol]

Hi Luches,

I STRONGLY recommend to get and keep PH between 6 and 6.5, otherwise you will run into iron deficiency, followed by (over 7) boron, coper zinc!

Just wait the PH reading of your new formula, it actually should get you a lower PH (at least somewhat).

You're spot on. The reading at 1.8 is now about 6.3. I've added MgSO4. by the way, but not the calcium chloride for the moment because it's only available in very large bags at a very high price.

I also came to an interesting realisation - when I first started out in hydroponics, my local supplier simply told me to use Hydrosol and calcium nitrate '50/50' which I took to mean equal quantities. But your formula is based on equal weight, and there's a difference. The calcium nitrate I use is 11% heavier than Hydrosol, which means a 10% reduction in it (using a weight-based mix) for starters.

Factoring this into your formula, I think my plants will be getting 35%-40% less N this year. I'll be keen to see the results.

Thanks again for your tremendous help.

Cheers,

Errol
PS I've uploaded a few photos to an album if you're interested in having a look at my setup.

[Luches]

You're most welcome!

Originally Posted by Errol

You're spot on. The reading at 1.8 is now about 6.3. I've added MgSO4. by the way, but not the calcium chloride for the moment because it's only available in very large bags at a very high price.

6.3 is fine if growing various plants - it will probably climb though, as uptake of acid components is supposed to be faster. Watch it happen ...
About the calcium chloride: it's necessary if your tap (or source water) hasn't got much calcium. What's the EC reading of your tap water? If it is between 0.1 and 0.2 (like mine), very little calcium is contained. If it's between 0.3 and 0.4 there should be 30-40 PPM of calcium contained anyway and calcium chloride isn't really needed. Please keep in mind that previously with your higher calcium nitrate content, you got lots of calcium too! Try to get a better source, specialized drug stores should have it in 1kg packages. I only pay about 1 USD $ per Kilo, food grade!

Originally Posted by Errol

I also came to an interesting realisation - when I first started out in hydroponics, my local supplier simply told me to use Hydrosol and calcium nitrate '50/50' which I took to mean equal quantities. But your formula is based on equal weight, and there's a difference. The calcium nitrate I use is 11% heavier than Hydrosol, which means a 10% reduction in it (using a weight-based mix) for starters.

They say: If the terrain differs from the map, stick with the terrain!

Originally Posted by Errol

Factoring this into your formula, I think my plants will be getting 35%-40% less N this year. I'll be keen to see the results.

Not sure about that percentage... let me check something...

Don't see me as a maniac, but you have to consider the actual EC versus gram/liter ratio of each component, to know how much less Nitrogen you use with the new mix


Mixing 1 Gram of Calcium Nitrate in 1 Liter of water, will result in 0.95-1.0 EC, while mixing 1 Gram of Magn. Sulph. in 1 Liter, will only give a reading of EC 0.66-0.70. You can "try that at home", but you'll need an accurate scale to do so. The ratio of Hydrosol has to be seen as an estimate, though. I haven't had Hydrosol handy and had to guess its composition in components to get to that number (0.76). In case you'll measure it, keep me posted if my estimate was accurate!

Originally Posted by Errol

PS I've uploaded a few photos to an album if you're interested in having a look at my setup.

Sure thing, glad to see it - I haven't found your post yet, will check again now...

Cheers,
Luches