Creating my own fertiliser

[Bjorn]

Ok, time is right:viking:
Its time to make your own fertiliser man.
Why do I do that? Simply because I do not feel that the available fertilisers fulfill my requirements.
Basically ;
Common fertilisers are too low in some of the micronutrients. Particularly manganese and zinc, probably boron, also possibly copper at my dilution level. I aim for a N(tot) around 15ppm

Stability of the micros is a challenge since I would like to avoid the use of EDTA.

Most available fertilisers have too much potassium and lack Calcium and magnesium. Except K-lite, but that has almost all N as nitrate and too little micros for my taste. Produces yellowish plants under my conditions. Should have approximately 50/50 NH4 and NO3 nitrogen. Urea gives NH4 nitrogen.

Ok I made a spreadsheet calculating the composite nutrient value of powder mixes and came to a mix that met most of my requiremets.

Then to my question; as this fertiliser is mostly based on sulphates it attains a rather high proportion of sulphate. Anyone that has information for or against sulphates in plant nutrition?
Thanks in advance.

 

[NYEric]

Nope, good luck.

 

[Ray]

The raws used in MSU fertilizers, including K-Lite, are pretty heavy in sulfates:

Components: boric acid, calcium nitrate, copper sulfate, iron EDTA, magnesium nitrate, manganese sulfate, potassium nitrate, potassium phosphate, sodium molybdate, zinc sulfate.

David Campen ought to be able to help; he makes his own.

 

[gonewild]

I don't remember ever seeing problems related to sulfates other than lack of sulfur.
There is some thought that higher levels of sulfates increase the uptake of other nutrients so maybe that is why growers using K-lite are getting good results with what seems like very low doses of nutrients.

Here is a document about sulfate effect on tomatoes. Tomatoes are a good reference plant as they show quick reactions to chemicals.
http://www.ptno.ogr.ar.krakow.pl/Wydawn/FoliaHorticulturae/Spisy/FH2005/PDF17012005/fh1701p08.pdf

 

[PaphMadMan]

Micronutrients as sulfate would not give you that much sulfate overall, and sulfur is a major nutrient usually supplied by sulfate, so I'm wondering what is in the mix that gives you so much sulfate you're worried about it, and how much are we talking about? Ammonium sulfate, potassium sulfate, magnesium sulfate are possible macronutrient sources that come to mind. But I doubt sulfate would be a direct problem even if it was the anion for every nutrient possible. You could probably use gypsum (calcium sulfate dihydrate) aggregate as a major potting mix component and not have "too much" sulfate.

 

[Bjorn]

Kirk, just to clarify, although also the micros are sulphate, its the macros that add most of the sulphate. You are right, I use ammonium sulphate and potassium sulphate, the nitrate comes separately, together with calcium and magnesium.I plan to add it through two injectors in succession.
My problem is the stability of the micros mainly. Since I have to add the micros with the macros except calcium and magnesium its definitely a possibility of precipitation as hydroxides or phosphate, particularly iron. I try to stabilise it with citric acid, but that is also not that straight forward it seems. Rather high dosages seems needed. And that has its influence on pH.
One very tempting posibility is to use kelp extract as the chelant. Since it contains rather large amount of aminoacids and chelates with amino-acids are responsible for a lot of the transport going on in the root region (lost the ref though) that could be an interesting approach.

 

[DavidCampen]

From a previous thread: http://www.slippertalk.com/forum/showthread.php?p=513173
This is the formulation that I am currently using:

117 g N (NO3/NH4 = 3.8/1)
21 g P2O5
83 g K2O
54 g Ca
15 g Mg
6 g S

1800 mg Fe
1600 mg Mn
800 mg Zn
600 mg B
300 mg Cu
200 mg Mo
200 mg NaCl
40 mg Co
20 mg Ni

This 2 solution formulation has calcium, magnesium, iron, manganese, zinc, copper, cobalt and nickel in solution A. Boron, molybdenum, phosphate and sulfate go into solution B. The quantities given above produce 1 liter of each solution. Since solution A contains ferric ammonium citrate it must be stored in amber or opaque bottles.

Potassium, ammonium, sodium and chloride can go into either solution.

I take it that you can get both calcium and magnesium nitrates but not potassium nitrate? Then for potassium you can use the sulfate and phosphate (monopotassium phosphate, MKP) and place that into solution B. Also for solution B I use sodium molybdate and boric acid (an equimolar amount of citric acid helps the boric acid dissolve).

For solution A I use all nitrates except that I use ferric ammonium citrate for iron. I use purchased calcium ammonium nitrate (water soluble / greenhouse grade) and magnesium nitrate. For the micronutrients - I purchased copper nitrate and ferric ammonium citrate and prepared the nitrates of zinc, manganese, cobalt and nickel from either the oxide or carbonate reacted with nitric acid. Nitric acid can be hard to get but I found that in the US and Canada, Technaflora brand pH-Down is dilute (about 10%) nitric acid and that was easy to get.

I buffer both solutions with diammonium citrate with the pH adjusted a bit upward with a potassium hydroxide based pH-Up. I prepare the diammonium citrate from citric acid and ammonium carbonate both of which I purchase as food grade materials. I also use ammonium nitrate which provides some pH buffering capacity but ammonium nitrate is becoming increasingly hard to obtain so I plan to replace this with monoammonium and diammonium phosphates in solution B as the ammonia source and as a pH buffer.

I can still purchase potassium nitrate; I used to purchase food grade potassium nitrate but this was expensive so recently I purchased a quantity of greenhouse grade material.

Manganese was purchased as the sulfate (plant nutrient grade) and precipitated from solution as the carbonate which was filtered and washed and then dissolved with nitric acid.

The zinc, cobalt and nickel were purchased as the oxide or carbonate from a pottery supplies company where they are sold for use in making glazes. These were then dissolved with dilute nitric acid to prepare the nitrates.

 

[naoki]

This sounds fun.

David, do you think you can possible post your "recipe"? I'm not good at chemistry, but if it is written in recipe form (e.g. 1M KNO3 xxx ml, 1M MgSO4 xxx ml etc), I can handle it. If you have a spreadsheet or something, I'd love to have it (if you don't mind).

Bjorn, if you are willing to share the spreadsheet, too, I'd like to have it. From my reading (of real scientific data of orchid nutrition), I vaguely remember NH4 lower than 50% seems to be generally safer (like David's). There appears to be fair amount of variation in NH4 tolerance within orchids, though. I've been adding a bit of ammonium nitrate to MSU and K-Lite.

I decided to design nutrient deficiency lab for the class I'm teaching this semester. Someone posted here about the experiment with sunflower, and it looked like fun.

 

[DavidCampen]

Zipped spreadsheet.

Here is a spreadsheet of my latest formulation.

 

[dodidoki]

I use regular NPK fretilizer with micros ( Substral for Balkony) 3g + Ca(NO3)2x4H2O 3g+ MgSO4X6H2O 3g added to 20 L RO water (6-7 ppm), and I dilute this solution up to 100 ppm with RO water.

I think it is not all the same if someone uses RO or tap water, eg. tap water is full of Ca and Mg carbonate, unchangeable hardness is 160 ppm at me( total hardness about 250 ppm).

NOTE: if anyone use Ca-nitrate with Mg-sulphate, be careful with them and add them to water at least 1 g/5l or weaker conc. and just after, not at the same time,when first salt has been soluted completely, other case fertilizer will be precipitated because of CaSO4

 

[Bjorn]

David, some very good info from you, but some of your procedures seem rather tideous, obviously you have access to some lab equipment or a small lab. I always liked to make one but never came that far at home, so I keep to simple procedures like mixing.
How did you attach the file? I have yet to find out how to do that? Give me a hint please.

Naoki, my spreadsheet is not straight forward to Digest, it just calculates the percentage of the components from the weight and the molar mass. If I find out how to post a file, I might post the file just to show what mixture we talk about.

Some of the ingredients are getting harder to get these days. Calcium nitrate is commonly used (actually partly calcium ammon nitrate) as fertiliser here and I use it with Epsom salt to make a solution of magnesium nitrate after decanting to get rid of the calcium sulphate that precipitates. You do not get rid of it all, but that does not matter, since it is afterwards mixed with the calcium nitrate solution. The precipitate is very fluffy so it takes time to settle properly, so expect some loss

Back to the getting harder; I get my stuff from e-bay, since its a lot of different salts I like not to do it through work so I buy it through e-bay. It has come to my attention that ammonium nitrate has disappeared due to its capability of making ANFO bombs (Oklahoma bomb and the one in Oslo) so I understand why its gone. Therefore I have kept to mostly sulphates and thought that ammonium sulphate was ok since it was readily available and commonly used as fertiliser in the EU. Then it took such a long time in the customs clearance so I started getting annoyed. Then suddenly I got a visitor at my work; and that visitor came from the police!

It turned out that the customs had reacted on the ammonium and the police was sent to check me up. I had a chat with the man and explained what I was going to use it for etc. and that was it. Some days later it was released and I got it.
Recently I have seen a listing of chemicals theyplan to ban, and it does not seem good for "kitchen" fertiliser production. So, better do it while its possible!

 

[myxodex]

Way to go Bjorn. I also got frustrated by not having much of a choice and so ended up making my own. I decided to follow some of the thinking behind Klite (i.e. Ca++ > K +), but also to use the bicarbonate from my hard tap water as part of the final mix. I had problems with medium acidification and so I read through the articles by Bill Argo on pH management. It was either Ray or Rick, I think, who originally posted the links to these articles. If you haven't read these then I highly recommend reading it before you finalise your fertiliser recipe (links on this page: http://staugorchidsociety.org/culture-water.htm ). In short it appears that NH4 causes acidification more efficiently than NO3 causes alkalinisation (? not sure why they're not equal),... anyhow I would be careful about a NH4:NO3 ratio of 50:50. If you plan to increase your micros (especially Cu), then an acidic medium is the last thing you want. When I did a rough and ready regression on Bill Argo's table of recommendations for the amount of HCO3 to buffer different amounts of NH4, I get a factor of 4.35 (i.e. for every 1ppm of NH4 you need 4.35 ppm HCO3 in your water: HCO3 (MW = 61) / NH4 as N (14) = 4.35, coincidence ?). For example, my tap water has 264 ppm HCO3 and 120 ppm Ca but only 4 ppm Mg, so I deliberately bias my Mg/Ca ratio in my fert recipe to account for some of the Ca coming from my tap water (I use about 4-5% tap water in my rain water to provide the HCO3). I've been using this for about 6 months and my pot pH appears to be stable in the range of 5.5 to 5.8, if stays like this I'll be very happy. My tap water also has approx 50 ppm SO4 so it also supplies some of the S. So in short my fert make up is designed with a rain/tap water mix in mind.

For the chelation you can prepare glutamic acid from monosodium glutamate (here in UK it is very cheap in oriental food stores) if you have a pH meter and some patience. Aspartic acid and histidine are sometimes available from dietary supplement suppliers. Be careful not to use DL racemic mixtures of amino acids as some D amino acids are known to be toxic to plants. Most chelates are made in slightly acidic solutions (pH in mid 5's OK); micro salts and organic ligands are heated separately in degassed (pre-boiled) water to a temperature in the range 70-80 deg C and then combined to form the chelate. Not sure all this hassle is strictly necessary for chelation but seems to be standard protocol in publications and patents.

I'm happy to give details if anyone is interested.

 

[Bjorn]

Myxo,
Interesting thread, as always, but I am not too certain that we can transfer those pH things from soil to the substrate we use. As a chemical engineer, I immediately see the acidifying effect of NH4+? ions, but that has to do with the equilibrium with water and will be recorded (and corrected) as the pH of the water you fertigate with.

And then the argument of the plant releasing a hydroxium ion to absorb the ammonium ion; well that is true, but at what rate do the orchids absorb these things? and what about the open structure of the mix?

A Third factor that should come into consideration is that if you fertigate with water at say pH around 5-6; then this pH is the result of many chemical interactions and hence has a significant buffer capacity. Particularly if organic acids are used. I use citric acid and I am confident that the buffer capacity of my water entirely overwhelms the little H+ that the plant may release. In soil, the situation is a bit diffrent, as the amount of water that flushes through is much smaller. I have seen graphs showing acidification of soil due to ammonium fertilisers, and it happens that is true, but mostly over decades. Wish my compost would last that long!

 

[Bjorn]

Addendum; I have not forgotten the nitrification bacteria, but I am uncertain to what extent they will acidify. Again due to the limited availability of the fertiliser. Remember, most ends on the floor!

 

[Paul]

Hi Bjorn,

I fertilize (not now, almost only municipal from december to mid-february and once a month only rain water + liquid fertilizer with kelp extract) like this with success (shiny leaves and nice roots, nice blooms):

rain water 80l + 8ml (~1 teaspoon) Ca-N (17-3) fertilizer + 16ml (2 teaspoons) liquid ocean fertilizer (1-3-5 NPK + many micros and others like natural hormones) + 8g (1 teaspoon) NH4NO3+MgSO4 (70%+30%, homemade)
Only once a week at most (april through september) and pots are flushed with municipal water (pH7 and EC 300µS/cm) between two fertilizing
The less I fertilize, the better are the roots, and municipal water helps to keep pH from 6 to 7 (this range makes all the elements available for the plant)

some species like anitum, papuanum or volonteanum grow as easily as roths or kolopakinigii do with the same water.

edit: water is never over 300µS/cm when fertilizing, and this fertilizing is not good for Catts, Vanda and other plants that like higher K levels and higher salts

 

[DavidCampen]

...
How did you attach the file? I have yet to find out how to do that? Give me a hint please.

..

Some of the ingredients are getting harder to get these days. Calcium nitrate is commonly used (actually partly calcium ammon nitrate) as fertiliser here and I use it with Epsom salt to make a solution of magnesium nitrate after decanting to get rid of the calcium sulphate that precipitates. You do not get rid of it all, but that does not matter, since it is afterwards mixed with the calcium nitrate solution. The precipitate is very fluffy so it takes time to settle properly, so expect some loss

...

Back to the getting harder; I get my stuff from e-bay, since its a lot of different salts I like not to do it through work so I buy it through e-bay. Recently I have seen a listing of chemicals theyplan to ban, and it does not seem good for "kitchen" fertiliser production. So, better do it while its possible!

To attach a spreadsheet file you have to first convert it into a .zip file, then you proceed in the same manner as for attaching a photo.

It would make things much easier if you could get magnesium nitrate.

I am stockpiling calcium, magnesium and potassium nitrates in anticipation of them becoming harder to acquire. I can still acquire ammonium nitrate using an indirect method but I will move my formulations away from using that in anticipation of even these indirect sources drying up. I make the assumption that I will always be able to get ahold of ammonium phosphates and sulfate.

 

[naoki]

Thank David. I also didn't know the trick to attach spreadsheet.

With the original question of sulfate, you are right, I couldn't find much about info about the negative effects. Marrchner's book don't mention about it.

I thought that it is interesting in this paper: Britto et al. 2002 NH4+ toxicity in higher plants: a critical review Journal of Plant Physiology 159: 567-584,
it mentioned:

Chemical changes in the plant induced by NH4 + exposure in- clude the well-documented total tissue depression, compared to NO3 – -fed plants, of essential cations such as potassium, calcium, and magnesium (Kirkby 1968, Salsac et al. 1987, van Beusichem et al. 1988, Boxman et al. 1991, Holl- dampf and Barker 1993, Troelstra et al. 1995, Gloser and Glo- ser 2000). This decline in cations other than NH4+ is accompanied by an increase in tissue levels of inorganic anions such as chloride, sulfate and phosphate (Kirkby 1968, Cox and Reisenauer 1973, van Beusichem et al. 1988). In addition, tissue levels of non-amino dicarboxylic acids, such as malic acid, often decline in NH4 + -grown plants, compared to plants grown on NO3–.....

I'll email you this paper (and a couple related) since you wants to try high NH4. Unlike other things discussed in ST, NO3:NH4 seems to be studied somewhat.

 

[naoki]

myxodex, if we are talking about the long-term acidification of media (lower pH of pour-through after year or so), and not the immediate effect, this quote might be interesting:

The results of this study show that the roots of Phalaenopsis may be the main cause of substrate acidification, which may have something to do with how originally the epiphytic roots absorb mineral nutrients in their natural habitat. Growth of Phalaenopsis is normal in a substrate with low pH; therefore, raising substrate pH may not be needed in the production of Phalaenopsis.

This is the final statement from a paper we discussed in ST:
http://hortsci.ashspublications.org/content/46/7/1022.abstract

Also, it mentions that another study showed that lack of certain minerals could cause acidification (Yen et al didn't think it is the case with their study of Phals).

I started to check pour-through pH in the last year or so, but I haven't encountered acidification yet (stable with 2 year-old cheap bark). What kind of pH are you getting after acidification?

 

[Bjorn]

Talking about acidification.......I checked it up onthe net and found that the main cause is the roots absorbing cations. Of course then, if the nitrogen is bound as a cation(ammonium) that would contribute a lot. Never thought of that before
But these results are typically from grass growth on pastures and I bet the nutrient absorbtion is much higher there than in a pot with a paphiopedilum. I think that it is not pH that kills the roots, I'll bet its accumulation of salts. hence the benefits of using very diluted fertigation.

 

[Brabantia]

Myxo,
Interesting thread, as always, but I am not too certain that we can transfer those pH things from soil to the substrate we use. As a chemical engineer, I immediately see the acidifying effect of NH4+? ions, but that has to do with the equilibrium with water and will be recorded (and corrected) as the pH of the water you fertigate with.

And then the argument of the plant releasing a hydroxium ion to absorb the ammonium ion; well that is true, but at what rate do the orchids absorb these things? and what about the open structure of the mix?

A Third factor that should come into consideration is that if you fertigate with water at say pH around 5-6; then this pH is the result of many chemical interactions and hence has a significant buffer capacity. Particularly if organic acids are used. I use citric acid and I am confident that the buffer capacity of my water entirely overwhelms the little H+ that the plant may release. In soil, the situation is a bit different, as the amount of water that flushes through is much smaller. I have seen graphs showing acidification of soil due to ammonium fertilisers, and it happens that is true, but mostly over decades. Wish my compost would last that long!

It is true that the fertilizer that contains ammonium (NH4+) are acidifying. They are used for culture of plants who love an acid substrate (azalea,rhododendron, ... ). A fertilyzer containing all its nitrogen as nitrate is not able to neutralize acidification due to the substrate degradation . A fertilyzer which contains most part of its nitrogen as ammonium only generates a small portion of the lowering of the pH observed. In my opinion the only solution is to use the buffer power of the bicarbonate contained in tap water if we do not want to add Sodium or Potassium. But on the long term the acidification of the substrate will occur because for reasons of fertilyser solutions conductivity we cannot add enough tap water.
Another solution would be to add dolomite (or other source of basicity) in the substrate as it has been done for years.
If we want a total control on the substrate pH the only solution is to use a substrate chemically inert ... culture on rockwool or expanded clay under all its forms (small balls, Seramis, Hydroton...).
See my table shown Here #23.