some kind of low K ...

[Paul]

hello,

I think I have to change a little my fertilization after looking at the explanations of Rick about the K too high in most fertilizers.
Mines are MSU like fertiliser (Akerne Rain mix) and makes some of my plants (the slow growing ones especially) become more compact (and then stopping completely) whereas blooms seem very good and plants make many (smaller) growths. the other is 28-14-14 plant prod (with urea and little ammonium), which I think compensate a litte the excess of K in the other one and urea makes growths bigger and just make some plants growing (they don't grow at all with only rain mix, for example micranthum)

My idea, before making our own formulation like Rick here in Europe, is to fertilize like this:

-municipal water, EC 300µS/cm pH 6.8, reduced to 6 with addition of nitric acid
-1.5g/10l 28-14-14
-1g/10l magnesium sulfate
-0.5g/10l dithane (mancozebe) as a source of Zn and Mn

that, applied during the growth period (march to novembre)

I remove the 28-14-14 in winter in order to lessivate the K in the pots and respect the plants rest.

what do you think of this?

 

[Brabantia]

@Paul pour pouvoir évaluer ton régime il faut que tu renseignes le ratio NNO3/NNH4 de l'engrais 28_14_14. (éventuellement l'urée).

 

[Paul]

So here we are:

after making all the mix I have these results:

pH = 6.0
EC = 540µS/cm

28-14-14 : N is 21% urea 4% nitric 3% ammonia. contains B, Cu, Fe, Zn, Mn (not enough Mn and Zn to my mind so I add dithane)
I have made some estimations of the final "product":

at least 80ppm N (about 42 nitric, 37 urea, 3 ammonium)
21ppm P
21ppm K
at least, 2.3ppm Mg
at least 15ppm Ca++

quite hard to evaluate Ca++ and Mg, as I don't know exactly if my water contains Mg
I've added 110ml/300l of nitric acid 38%

 

[Rick]

So here we are:

after making all the mix I have these results:

pH = 6.0
EC = 540µS/cm

28-14-14 : N is 21% urea 4% nitric 3% ammonia. contains B, Cu, Fe, Zn, Mn (not enough Mn and Zn to my mind so I add dithane)
I have made some estimations of the final "product":

at least 80ppm N (about 42 nitric, 37 urea, 3 ammonium)
21ppm P
21ppm K
at least, 2.3ppm Mg
at least 15ppm Ca++

quite hard to evaluate Ca++ and Mg, as I don't know exactly if my water contains Mg
I've added 110ml/300l of nitric acid 38%

What is the hardness of your tap water? It is very rare that municipal water will have more Mg than Ca. I would reduce the total amount of fertilizer to at least have more Ca than K.

My plants are thriving with only getting 4 or less ppm K and 20-30 ppm N

 

[Paul]

my water is 12.5 french °F hardness. EC is 300µS/cm

I can divide the 28-14-14 by 2, so I would have the same amount of Calcium and Magnesium, but NPK would be about 60-10-10, Ca~15 and Mg~2.5 if I'm not wrong
+Mn, Zn and a little of the other micro-elements (more or less, depends on the municipal water)

the final solution will have EC = 500µS/cm, that should be suitable for most species.

 

[Rick]

my water is 12.5 french °F hardness. EC is 300µS/cm

I can divide the 28-14-14 by 2, so I would have the same amount of Calcium and Magnesium, but NPK would be about 60-10-10, Ca~15 and Mg~2.5 if I'm not wrong
+Mn, Zn and a little of the other micro-elements (more or less, depends on the municipal water)

the final solution will have EC = 500µS/cm, that should be suitable for most species.

Ok 12.5 F hardness equivalent to 125 mg/L as CaCO3. (medium hard by US standards) Given usual 5:1 ratio of Ca to Mg in surface waters then its not unreasonable to have about 35-40 ppm soluble Ca and 8-10ppm Mg.

Where are the Ca~15 and Mg~2.5 coming from? Is that in the fertilizer?

Also you have a short fertilizing season. I fertilize year round.

 

[Paul]

OK, could you help me in my estimations, please?

I add 1g/10l of magnesium sulfate. does it make 2.5ppm of Mg?
I add 110ml/300l of nitric acid (38% rate) that should give 38ppm N so I estimate there could be 19ppm of Ca++ (but maybe a little Mg++ too)
is it right or not?
0.75g/10l of 28-14-14 should make 40ppm N, 10ppm P (P2O4) and 10ppm K (KNO3)

Am I right or not?

 

[Rick]

OK, could you help me in my estimations, please?

I add 1g/10l of magnesium sulfate. does it make 2.5ppm of Mg?
I add 110ml/300l of nitric acid (38% rate) that should give 38ppm N so I estimate there could be 19ppm of Ca++ (but maybe a little Mg++ too)
is it right or not?

Am I right or not?

Starting with the first two.

MgSO4 is ~20% Mg(for anhydrous) and ~10%(for hydrated Epsom salt.

1gr(1000mg)/10l = 100mg/L so 20mg/L of Mg from anhydrous or 10ppm from Epsom salt. And add this to the amount in your tap water which could add about 8 or so mg if you have similar water to US.

nitric acid does not contain any calcium nor does it remove calcium from water So adding nitric acid to your tap water, will reduce bicarbonate ion, but not calcium. I think I estimated that the calcium concentration in your tap water is about 30-40ppm (mg/L) based on the hardness of 12+ French hardness units.

 

[Rick]

OK, could you help me in my estimations, please?

0.75g/10l of 28-14-14 should make 40ppm N, 10ppm P (P2O4) and 10ppm K (KNO3)

Am I right or not?

Actually I come out to 21-10-10, but that doesn't account for the N input from your nitric acid. Which I can't compute without knowing the normality (or % concentration) of material used).

The agriculture convention for NPK I believe is N, P204, and KO.

The P could be PO5, but can't recall for sure.

 

[Rick]

my water is 12.5 french °F hardness.

I noticed in definitions that Europeans use the word "hardness" for both hardness and alkalinity(buffering capacity).

This could cause confusion since hardness in US refers to the concentration of Ca and Mg ions while alkalinity is a measure of bicarbonate (HCO3) ion. Both measures are typically expressed as mg or ppm as CaCO3, but that unit expression is not meaningful for determining actual Ca, Mg, and HCO3 concentrations.

 

[atlantis]

I noticed in definitions that Europeans use the word "hardness" for both hardness and alkalinity(buffering capacity).

That´s not an "european concept".
Many people have a wrong concept of these parametres.

 

[Stone]

So here we are:

after making all the mix I have these results:

pH = 6.0
EC = 540µS/cm

28-14-14 : N is 21% urea 4% nitric 3% ammonia. contains B, Cu, Fe, Zn, Mn (not enough Mn and Zn to my mind so I add dithane)
I have made some estimations of the final "product":

at least 80ppm N (about 42 nitric, 37 urea, 3 ammonium)
21ppm P
21ppm K
at least, 2.3ppm Mg
at least 15ppm Ca++

quite hard to evaluate Ca++ and Mg, as I don't know exactly if my water contains Mg
I've added 110ml/300l of nitric acid 38%

Paul, where is the Sulphur? S should be about 25% of your N. Very IMPORTANT! without enough S your plants can become stunted. S is lost very quickly in drainage water. You should use rock Gypsum 2-4mm 1 grm/liter of mix every 6 months. (unless your fertilizer or water has enough)

 

[Rick]

Mike

I believe there is some MgSO4 in the mix.

Also with a hardness of 125 and conductivity 300, there is usually a lot of sulfate as the matching anion for all the Ca/Mg cation.

Some of the anion will be bicarbonate ,and depending on the geography there could be a significant amount of chloride. But it's kind of rare for surface waters to be low on sulfate and high in chloride.

 

[Paul]

hello,

The analysis of municipal water, in november 2012 showed me there is already 29mg/l of NO3, that's 29ppm isn't it?

So if I had the 40ppm of N with nitric acid, it makes about 70 ppm N, right?

So, maybe I just need to add about 0,5g/10l of 28-14-14 fertilizer, that will make about 85ppm Nitrogen which would be much enough, + at least 7ppm P and 7 ppm K (probably more if I can get a complete water analysis)

I would have a 12-1-1 fertilizer with probably about 5-2 Ca-Mg values. There is probably sulphur too in the water. I will ask for the complete analysis if possible, that should be intersting to adjust my values!

 

[dodidoki]

Paul, why don't you buy an RO system? Not too expensive, only problem is waste water, but I use it for wetting the floor.
Ro water very good, I measured: 6 ppm only, so there is no problem with "unknown" ions if you would like to make an exact fertilizer solution.

Otherwise I'm on Rick's way now for few weeks, I made next formula:

N: 14 % ( 7% NO3, 3,5% Urea, 3,5% NH4)
P: 4 % (P2O5)
K: 3 % (K2O)
Mg.: 4% ( 1% EDTA, 3% free Mg2+ as Mg So4)
Ca: 10% ( as Ca(NO3)2 )

+ micros

There is just some week behind me -I know little time-but some roots are forming now and old "roots stop and die" problem seems to be disappeared.

 

[Paul]

Hi,
If I want pure water, I just have to take rain water. Here, it is as pure as RO water would be (or almost). It would be low cost and just need a large tank (1m3 at least)
the goal is to have, right now, with no more cost, quite a good water for my plants. Maybe it would be better to use pure water and make my own well known formula (or waiting for an European low-K fertilizer), but I will wait a little...

 

[DavidCampen]

hello,

The analysis of municipal water, in november 2012 showed me there is already 29mg/l of NO3, that's 29ppm isn't it?

So if I had the 40ppm of N with nitric acid, it makes about 70 ppm N, right?

29mg/l of NO3 is 6.5mg/l of N which is 6.5 ppm N.

 

[Rick]

29mg/l of NO3 is 6.5mg/l of N which is 6.5 ppm N.

With NO3 really need to check the units because Davids math is correct for the N ppm (which is a typical measuring convention) versus the whole ion (NO3) mg/L.

Usually nitrogen species (ammonia, nitrite, nitrate) are represented as mg/L-N

However, either 6.5ppm N or 29 mg/L NO3 is a lot of nitrate for municipal waters. Seems like that should be above typical drinking water standards.

 

[DavidCampen]

Heh, completely off topic - some years ago I spent a couple weeks on a ranch in New Mexico that was surrounded by BLM grazing land. The tap water stank of cows, I could barely stand to shower in it much less drink it; I drove 20 miles into town to buy cases of bottled water.

 

[Ray]

I would have been right there with you, David! Manure may be perfectly "natural" and "organic", but...