Rot or Not? Please help

[MikeInOz]

Urea has 46.7% N
Ammonium sulphate has 21% N
Calcium nitrate has 17% N
Potassium nitrate has 13.8% N
Ammonium nitrate has 35% N
You can work out what you want from there. if you want to acidify or stop alkalization use more Ammonium and/or urea
If you want to reduce acidity or stop it from falling, use mainly nitrate. I like to use mainly NH4 and use a liming material. Urea => ammonium => nitrate.
For air plants (tillandsias) I use about 50/50 HN4 and NO3 because there is no soil.

[Steve Johnson]

Are there any risks or adverse effects associated with the acidification of hard water, whether it be changes in elemental composition or the water or impact on soil media/cacti health? For example, calcium acetate is a phosphate binder - unsure if that in turn makes phosphorous less available to the plant? Does the addition of an acidifier impact the soluble fertilizer that is added after through other reactions or do fertilizers ever change the pH of tap water rendering cal/mag more available?

Ah, interesting questions. I went onto DuckDuckGo (my search engine of choice these days), and I typed in "phosphate binders in plants". Almost all of the results I got involve human health, but I couldn't find anything that answers your question regarding what it would mean in terms of plant health. My uneducated guess -- if calcium acetate is a phosphate binder, I don't think it matters if this makes P more or less available to our cacti. If the availability is less, I can't imagine that it would be significant enough to worry about.

Regarding your 3rd question, we'll begin with this nutrient availability chart:

pH_nutrient_ availability_ chart01.jpg (81.4 KiB) Viewed 515 times

Fertilizers usually lower the pH of the water a little bit, so here's the basic acidification procedure:

• Step 1 -- test the pH of your tap water.

• Step 2 -- add the fertilizer and any fert supplements you're using, then test the pH again.

• Step 3 -- add the acidifier last. Aim for a final pH of 6.0 in the watering solution if the mix is pH-neutral. If the mix is alkaline, increase the amount of acidifier. If the mix is acidic, reduce the amount.

I just gave you a simplified version of step 3, so I'll cover the more detailed one when I put together a new "how to" guide. In fact, this conversation kinda lit a fire under me to do it ASAP. One thing I'll mention before I sign off for now -- when you acidify tap water, it'll undergo pH rebound. For example, if your water-saturated mix starts out with a pH of 6.0, it'll gradually rebound up to 7.0 or thereabouts by the time the mix dries out.

[hoopgod32]

Ah, interesting questions. I went onto DuckDuckGo (my search engine of choice these days), and I typed in "phosphate binders in plants". Almost all of the results I got involve human health, but I couldn't find anything that answers your question regarding what it would mean in terms of plant health. My uneducated guess -- if calcium acetate is a phosphate binder, I don't think it matters if this makes P more or less available to our cacti. If the availability is less, I can't imagine that it would be significant enough to worry about.

Thanks Steve! Extremely helpful. As you mentioned, it doesn't seem there's much plant-related research for phosphate binding. I'm surprised there isn't much info out there if but to dispel any concerns considering it's use within humans. Clearly there is some reaction at an elemental level. I'd be curious for someone more well-versed in chemistry to dig into it and/or share their knowledge.

I just gave you a simplified version of step 3, so I'll cover the more detailed one when I put together a new "how to" guide. In fact, this conversation kinda lit a fire under me to do it ASAP. One thing I'll mention before I sign off for now -- when you acidify tap water, it'll undergo pH rebound. For example, if your water-saturated mix starts out with a pH of 6.0, it'll gradually rebound up to 7.0 or thereabouts by the time the mix dries out.

Wahoo! Looking forward to reading it. I stumbled on this very in-depth piece all about water alkalinity/pH and why it's so important for it to be right for watering cacti, whether in-ground or potted. The one glaring thing missing is a reference to the added benefit of increasing the availability of cal/mag in hard water through the process of acidification. Hopefully it helps as you compose a new guide! -- I now see you linked this same guide way back in 2012, forgive me!

Btw - are the test strips you linked significantly better than say a digital pH/hardness meter like this? I know the strips test for many more things, but mainly focused on usefulness and repeatability.

[Steve Johnson]

I stumbled on this very in-depth piece all about water alkalinity/pH and why it's so important for it to be right for watering cacti, whether in-ground or potted. The one glaring thing missing is a reference to the added benefit of increasing the availability of cal/mag in hard water through the process of acidification. Hopefully it helps as you compose a new guide! -- I now see you linked this same guide way back in 2012, forgive me!

No worries. While I appreciate what the article did to highlight the importance of acidifying hard water, a few CactiGuide members with a chemistry background reviewed it and found Roberts' and Burleigh's understanding of chemistry to be highly suspect. Elton Roberts considers himself to be an authority among hobbyist growers who don't know any better -- hardly a surprise that he says nothing about how acidification takes Ca and Mg from the tap to the plant. If he doesn't understand the importance of that, need I say more?

Btw - are the test strips you linked significantly better than say a digital pH/hardness meter like this? I know the strips test for many more things, but mainly focused on usefulness and repeatability.

Nope, a digital pH meter is way more accurate than test strips for reading pH. And yes, repeatable results -- you hit the nail on the head there. My meter of choice used to be the Milwaukee Instruments pH 600. After the electrodes on my last one crapped out, I upped my game last year with this:

https://www.amazon.com/Poniie-PH2022Plu ... 776&sr=8-1

Unfortunately, the item isn't available on Amazon anymore. But as good as the Poniie PH2022 Plus is, the meter you mentioned could be even better. Not sure if I would use it to measure EC and TDS, but I'm always up for learning new things, so maybe I should learn about what they do. Regarding test strips -- if nothing else, they're useful for reading the ppm values of total hardness and carbonate hardness in tap water. I just compared the MedLab 17 in 1 strips with the 7 in 1 aquarium test strips made by Saysummer I bought last year, and I got basically the same GH and KH readings, so I think either product would be reliable enough for our purposes.

[hoopgod32]

No worries. While I appreciate what the article did to highlight the importance of acidifying hard water, a few CactiGuide members with a chemistry background reviewed it and found Roberts' and Burleigh's understanding of chemistry to be highly suspect. Elton Roberts considers himself to be an authority among hobbyist growers who don't know any better -- hardly a surprise that he says nothing about how acidification takes Ca and Mg from the tap to the plant. If he doesn't understand the importance of that, need I say more?

Ya know what, you're right! I drew some value from the paper, but it's good to know their knowledge isn't actually as well rounded as presented. Sounds like there's a real opportunity to fill in all the gaps with a revised and more accurate master version on proper watering techniques! My first ask: don't mention sulfuric acid (highly tissue corrosive) as an acidifier option like they do lol.

Nope, a digital pH meter is way more accurate than test strips for reading pH. And yes, repeatable results -- you hit the nail on the head there. My meter of choice used to be the Milwaukee Instruments pH 600. After the electrodes on my last one crapped out, I upped my game last year with this:

https://www.amazon.com/Poniie-PH2022Plu ... 776&sr=8-1

Unfortunately, the item isn't available on Amazon anymore. But as good as the Poniie PH2022 Plus is, the meter you mentioned could be even better. Not sure if I would use it to measure EC and TDS, but I'm always up for learning new things, so maybe I should learn about what they do. Regarding test strips -- if nothing else, they're useful for reading the ppm values of total hardness and carbonate hardness in tap water. I just compared the MedLab 17 in 1 strips with the 7 in 1 aquarium test strips made by Saysummer I bought last year, and I got basically the same GH and KH readings, so I think either product would be reliable enough for our purposes.

The one I linked looks very similar! Unsure if as accurate, but price is decent. Going to look around and see if there's anything with very positive reviews. The test strips can maybe help give some more info on any carbonate build up for when I test soil pH too? If anything, will be good for experimenting and learning.

[Steve Johnson]

My first ask: don't mention sulfuric acid (highly tissue corrosive) as an acidifier option like they do lol.

Agreed -- way too dangerous for hobbyist use, and best if we leave it to the professionals who know what they're doing.

Going to look around and see if there's anything with very positive reviews.

What would be even nicer? Test strips that include ppm readings for Ca and Mg in the water, but apparently they don't exist. If you do find them, let me know!

[hoopgod32]

As a general rule, I aim for a Nitrate-Ammonium ratio of about 2-1, and IMO this tallies well with what we see in the quotes. Sorry, but I can't recommend the Mega Grow fertilizer for cacti.

Ok I did some pretty exhaustive digging for soluble fertilizers. A few interesting options I found that I'd be curious to get thoughts on! All include the assumption that hard water is supplying sufficient cal/mag.

Rare Dankness Nutrient Bloom (10-10-19)

• 1:0.44:1.58 elemental

• Phosphorous outside of the 0.25-0.35 range but I do see old comments referencing 0.4?

• 2-1 nitrate/ammonia ratio

Jack's Professional General Purpose (20-10-20)

• 1:0.22:0.83 elemental

• Slightly below lower phosphorous bar of 0.25

• Would require potassium sulfate addition to correct ratio and add missing sulfur

• 3-2 nitrate/ammonia ratio

Masterblend Pot Mum Formula (15-10-30)

• 1:0.29:1.67 elemental

• No sulfur listed but contains magnesium sulfate? Could add some additional epsom salt

• 2.75-1 nitrate/ammonia ratio

[Steve Johnson]

The Masterblend Pot Mum Formula appears to be the most promising, although I'll have to dig into it more before I come to any conclusions.

The only problem we have with dry water-soluble fertilizers is that they need to be diluted by weight, not volume. For example, a teaspoon of fertilizer won't have the same weight as a teaspoon of sugar. Measuring accuracy is really important to determine the amounts of nutrients going into a watering solution -- without knowing what the nutrient dosages are in parts-per-million, we won't know if those dosages are just right, too much, or not enough per feeding. Easy to do with liquid concentrates diluting by volume because the nutrient percentages are the same regardless if it's 1/2 tsp., 1 tsp., etc. A good digital scale measuring down to .01 gram is a far more accurate way of diluting with dry ferts. If you don't mind going that route and you need a digital scale, this is my scale of choice:

https://www.homesciencetools.com/produc ... g-x-001-g/

Not expensive, and it includes a 200 g calibration weight -- this one is way better than the cheapo scales we find on Amazon.

I'll follow up with you as soon as I can.

[Steve Johnson]

Okay, I did the math for the Masterblend 15-10-30 -- dilution is 1.8 grams per gallon of water. Now here's the nutrient breakdown:

• 11.03% Nitrate N -- 0.20 g/53 ppm
  3.97% Ammonium N -- 0.07 g/18 ppm
  Total N = 15% -- 0.27 g/71 ppm

• 4.36% elemental P -- 0.08 g/21 ppm

• 24.9% elemental K -- 0.45 g/119 ppm

• 0.115% Mg (derived from magnesium sulfate in the fert) -- .002 g/0.55 ppm

• 0.152% S (derived from magnesium sulfate in the fert) -- 0.0027 g/0.72 ppm

• 0.01% Mo -- 0.00018 g/0.05 ppm

The ppm dosages of N, P, and K per feeding are quite good. Of all the fertilizers I've seen, Masterblend is the only one that gets it right on the amount of molybdenum required for efficient conversion of nitrate to usable N in the plant. I'd just like to explain what Mo does -- the details from Nutrient Tech:

Molybdenum.jpg (87.47 KiB) Viewed 334 times

The sentence underlined in red suggests that we could increase the Mo without overdoing it, but best if we stick with Mike's recommendation:

All hydroponic solutions for various crops contain 0.05ppm Mo. It does not seem to vary among different crops so perhaps that is a standard optimum amount. Aim at that and you should be fine.

Although the sentence underlined in black pertains to crop production, the same applies to cacti and succulents.

It would be awfully nice if we had Ca, Mg, and S with the right amounts wrapped up in one neat little package, but that's where the Masterblend 15-10-30 falls short. Gypsum provides a slow-release form of Ca and S, so a small amount of gypsum granules in your mix should do the job. Since you don't know about the levels of Ca and Mg in your hard water, getting the ppm numbers through test results from JR Peters is better than trying to guess. If all the numbers line up to give you a Ca-Mg ratio of 2-1 or 3-1 in the water, Ca added by the gypsum means you're set. But if there's no Mg in your water, a dash of magnesium sulfate in your watering solution is required. Once you give me the ppm number for Ca in your water, I can help you figure out the proper magnesium sulfate dilution.

Rare Dankness Nutrient Bloom (10-10-19)

• 1:0.44:1.58 elemental

• Phosphorous outside of the 0.25-0.35 range but I do see old comments referencing 0.4?

Yes, and that's why I updated my "Fertilizers explained" presentation here:

https://www.cactiguide.com/forum/viewto ... 10#p401210

As my math teachers used to say, "show your work!" Hope you don't mind all the math exercises in that post.

I'll sign off for now with a little something regarding forms of nitrogen...

We had an expert grower on the forum who also had a background in chemistry. Here's a quote from one of his posts on the subject:

Plants utilise Ammonium ions directly to synthesise amino acids as the essential building blocks of the plant. Nitrate ions have to be reduced in two stages before they become Ammonium ions and can be used for making interesting chemicals. This may be the source of the naive idea that Nitrate source nitrogen is somehow "slow" to absorb or slow to become useful. Nitrate is actually extremely fast acting in plants, and as any good gardener will tell you Nitrate fertiliser produces the fastest greening effect. Not only can Nitrate ions be converted to Ammonium ions extremely quickly in the plant (do we care if the nitrogen is available today or tomorrow?), but it has other benefits (or at least differences) to the utilisation of Ammonium ions. Ammonium ions are absorbed and used directly in the roots, and little or none may be transported to the rest of the plant. Nitrate ions are transported directly to the leaves (or photosynthetic stems) and can either be stored there or converted to Ammonium ions for immediate use. Ammonium ions are not generally stored by plants. All these statement should be considered general, and there is considerable variation in different plants.

So just this tiny insight into plant chemistry shows that Nitrate and Ammonium perform differently in the plant and each would be the best solution (sic) in different conditions. The hundreds of papers on this subject show the same thing. Different plants, or the same plant in different conditions, may take up one or other ion preferentially but are quite capable of doing it from a mix of available Nitrogen forms. In any case, they usually perform best when they are able to take up both forms. The rare benefits to applying just a preferred single form of Nitrogen (which can be either Nitrate or Ammonium) are far outweighed by the dramatically poor performance in most cases of applying only the "wrong" single form.

Some valuable learning there. As long as our cacti get ammonium N and nitrate N, we don't need to be strict about ammonium-to-nitrate ratios. The only thing iann didn't mention (maybe he didn't know about it?) -- the importance of Mo to the nitrate conversion processes in the plant.

[hoopgod32]

Okay, I did the math for the Masterblend 15-10-30 -- dilution is 1.8 grams per gallon of water. Now here's the nutrient breakdown:

• 11.03% Nitrate N -- 0.20 g/53 ppm
  3.97% Ammonium N -- 0.07 g/18 ppm
  Total N = 15% -- 0.27 g/71 ppm

• 4.36% elemental P -- 0.08 g/21 ppm

• 24.9% elemental K -- 0.45 g/119 ppm

• 0.115% Mg (derived from magnesium sulfate in the fert) -- .002 g/0.55 ppm

• 0.152% S (derived from magnesium sulfate in the fert) -- 0.0027 g/0.72 ppm

• 0.01% Mo -- 0.00018 g/0.05 ppm

The ppm dosages of N, P, and K per feeding are quite good. Of all the fertilizers I've seen, Masterblend is the only one that gets it right on the amount of molybdenum required for efficient conversion of nitrate to usable N in the plant. I'd just like to explain what Mo does -- the details from Nutrient Tech:

Molybdenum.jpg

The sentence underlined in red suggests that we could increase the Mo without overdoing it, but best if we stick with Mike's recommendation:

All hydroponic solutions for various crops contain 0.05ppm Mo. It does not seem to vary among different crops so perhaps that is a standard optimum amount. Aim at that and you should be fine.

Although the sentence underlined in black pertains to crop production, the same applies to cacti and succulents.

Thanks so much for this breakdown Steve! I really appreciate and hope it ends up being worthwhile. I reached out directly to Masterblend as I don't see this fertilizer available at online retailers and they note on their site their don't sell retail quantities to consumers. Fingers crossed there's a way to get it somehow! I'll update here when I hear back.

It would be awfully nice if we had Ca, Mg, and S with the right amounts wrapped up in one neat little package, but that's where the Masterblend 15-10-30 falls short.

Yeah, I have to send in that water sample to properly understand the baseline I'm working with. Definitely agree it's close to being an all-in-one! The only soluble fertilizer combo I know of that includes Ca, Mg and S is this combo from Masterblend whose ratio is 1:0.4:1.62. Unfortunately, it's mainly nitrate nitrogen (only 1.5% ammonia) and phosphorous is barely above the updated range. A lot of san pedro growers use it but like you said, specific needs. Truly so close!

[Steve Johnson]

Yeah, I have to send in that water sample to properly understand the baseline I'm working with. Definitely agree it's close to being an all-in-one! The only soluble fertilizer combo I know of that includes Ca, Mg and S is this combo from Masterblend whose ratio is 1:0.4:1.62. Unfortunately, it's mainly nitrate nitrogen (only 1.5% ammonia) and phosphorous is barely above the updated range. A lot of san pedro growers use it but like you said, specific needs. Truly so close!

I know the feeling -- so close, yet so far away. Unfortunately cacti and succulents are a niche hobby, the problem being that not one US manufacturer formulating all-in-one fertilizers designed "for cacti and succulents" knows anything about the horticultural science behind what the plants need for optimal growth. Oddly enough, the Grow More 17-8-22 Bromeliad and Tillansia plant food I recommended for CoolestGravy (see https://www.cactiguide.com/forum/viewto ... 00#p406000) may be just the ticket. The fertilizer contains 6.4% ammonium N and 10.5% nitrate N, so that's a good balance between the two. Its "derived from" statement lists ammonium phosphate, potassium phosphate, ammonium sulfate (there's you S), potassium nitrate, ammonium nitrate, Manganese EDTA, Iron EDTA, Zinc EDTA, plus blood meal and kelp meal extracts. (Not sure what the blood mean and kelp meal do, but maybe some can explain it.) The true elemental P and K values make it 17-3.49-18.26. The P and K sides of the ratio are 0.21 and 1.1. Of the "big 3" major nutrients, ornamental plants need the least amount of P, and I wouldn't worry about it unless a fert had 0.15 or less. I wouldn't worry about K being on the lower end of the 1.1-1.7 range either, although you can bring it up with potassium sulfate. For Ca and Mg, you can supplement your watering solution with nitrogen-free TPS CalMag. The Ca in your hard water helps. Mg in the water would help too, although you'll have to find out if you even have it. I'm recommending 1/4 tsp. per gallon for now -- once you get the results of your water test from JR Peters, we can determine if the dilution is right or you need to up it to 1/2 tsp. per gallon.

You'll need to do something about Mo, so a sodium molybdate stock solution will be required. If you want to supplement the 17-8-22 with potassium sulfate, you'll need a stock solution for that too. I can guide you on how to make the stock solutions, but for that, you'll also need a digital scale measuring down to 0.01 gram. If you already have one, great. If not, the one I recommended for you earlier will do the job well. Since the Grow More 17-8-22 is a dry water-soluble fert, that scale will come in handy for accurate dilution. If you'd like to go for it, I'll run the calculations and come up with the right dilution for you.

[MikeInOz]

any good gardener will tell you Nitrate fertiliser produces the fastest greening effect.

That is not my experience. Nitrate is inferior to ammonium in some situations and can cause yellowing rather than greening. For example plants which need acidic soil conditions may do not do well with nitrate. This includes many cacti of course. For example, Gymnocalycium, Notocactus, Echinopsis, Rebutia, many cereus, Parodia, Probably Copiapoa, plants from Baja California and other volcanic soils and on an on.

Ammonium ions are absorbed and used directly in the roots, and little or none may be transported to the rest of the plant.

That is just nonsense.

Nitrate ions are transported directly to the leaves (or photosynthetic stems) and can either be stored there

Stored and unused Nitrate is believed to be a major source of food for pathogens.

The rare benefits to applying just a preferred single form of Nitrogen (which can be either Nitrate or Ammonium) are far outweighed by the dramatically poor performance in most cases of applying only the "wrong" single form.

More nonsense. Each year 100s of millions of nursery plants of all kinds are fed with Osmocote or other ammonium fertilizers and urea which often have no or almost no nitrate.

[Steve Johnson]

any good gardener will tell you Nitrate fertiliser produces the fastest greening effect.

That is not my experience. Nitrate is inferior to ammonium in some situations and can cause yellowing rather than greening. For example plants which need acidic soil conditions may do not do well with nitrate. This includes many cacti of course. For example, Gymnocalycium, Notocactus, Echinopsis, Rebutia, many cereus, Parodia, Probably Copiapoa, plants from Baja California and other volcanic soils and on an on.

Ammonium ions are absorbed and used directly in the roots, and little or none may be transported to the rest of the plant.

That is just nonsense.

Nitrate ions are transported directly to the leaves (or photosynthetic stems) and can either be stored there

Stored and unused Nitrate is believed to be a major source of food for pathogens.

The rare benefits to applying just a preferred single form of Nitrogen (which can be either Nitrate or Ammonium) are far outweighed by the dramatically poor performance in most cases of applying only the "wrong" single form.

More nonsense. Each year 100s of millions of nursery plants of all kinds are fed with Osmocote or other ammonium fertilizers and urea which often have no or almost no nitrate.

Well, so much for iann's "expertise". He sure came off as an expert, and he treated us like we were idiots in some of his posts. Glad to have you setting the record straight.

[hoopgod32]

That is not my experience. Nitrate is inferior to ammonium in some situations and can cause yellowing rather than greening. For example plants which need acidic soil conditions may do not do well with nitrate. This includes many cacti of course. For example, Gymnocalycium, Notocactus, Echinopsis, Rebutia, many cereus, Parodia, Probably Copiapoa, plants from Baja California and other volcanic soils and on an on.

This is news to me. I have many of the cacti you listed (Notocactus schlosseri, Notocactus Haselbergii, Parodia leninghausii, Echinocereus rigidissimus, etc) all currently in acidic soil around 6 pH (don't most cacti prefer acidic?). To confirm, they will not do well with a fertilizer that has majority nitrate for example in say a 3:2 ratio? Are you able to share why that is exactly and if it's dangerous to provide any nitrate to them over the long term?

[Steve Johnson]

That is not my experience. Nitrate is inferior to ammonium in some situations and can cause yellowing rather than greening. For example plants which need acidic soil conditions may do not do well with nitrate. This includes many cacti of course. For example, Gymnocalycium, Notocactus, Echinopsis, Rebutia, many cereus, Parodia, Probably Copiapoa, plants from Baja California and other volcanic soils and on an on.

This is news to me. I have many of the cacti you listed (Notocactus schlosseri, Notocactus Haselbergii, Parodia leninghausii, Echinocereus rigidissimus, etc) all currently in acidic soil around 6 pH (don't most cacti prefer acidic?).

Generally speaking, North American species are ev0lutionarily adapted to alkaline soils, and South American species are ev0lutionarily adapted to slightly acidic soils. (And yes, there are exceptions.) Doesn't necessarily mean they prefer the pH of their native soils when they're being grown under pot cultivation. I grow North and South American species, my pumice-granite gravel mix is pH-neutral, and all of them grow well in it. Based on 12-plus years of good experience, I've found that a 2-1 nitrate-ammonium ratio is fine. Nice thing about a pH-neutral mix -- you don't have to worry about coming up with an alkaline mix for some species and an acidic mix for others.