The Cal-Mag of my dreams?

[greenknight]

You need to be especially careful about Ph modification with the gritty mineral mixes used for growing desert cacti. Organic matter and clay have many more surface sites that can hold hydrogen ions, it takes more to change their Ph, so they act as buffers against Ph changes. They also hold a lot of water, though, so you can't use a lot of clay or organic matter in your cactus mix, you just have to use caution when modifying the Ph.

[MikeInOz]

"Steve Johnson" post_id=398439 time=1673068509 user_id=4655]

• Since hydroponic fert manufacturers seem to tilt heavily in favor of Nitrate N, they may know something we don't.

• Iann's last statement suggests that desert cacti in the wild prefer Nitrate. Either that or it's their only significant soil-based Nitrogen source.

You can take the cactus out of the desert, but can you take the desert out of the cactus? Just a theory -- generations of desert species seed-grown in nurseries share the same genetic heritage as their wild counterparts, so it stands to reason that desert cacti under cultivation do prefer Nitrate N in the ferts they get.

I don't know for sure. I did read that ''dry-land'' plants prefer NH4 somewhere but it's probably not as simple as that. What is known is the NH4 tends to reduce the alkalinity of a soil and NO3 tends to increase it so that should probably be kept in mind in some circumstances. (eg if your water is already alkaline)
Also, ammonium is converted to nitrate in warm moist soils with a pH higher than about 6 so a good proportion of the ammonium would be converted
due to the infrequent watering/fertilizing.
Another factor would be that many of the cacti we grow come from semi forest and grasslands where the mineralization of the dead plants will release ammonium during the wet seasons. In my case, I would need to revert to liquid feeding if I was to experiment with an all nitrate N (or mainly nitrate N) and my plants (including the desert types) are growing and flowering so well I can't see myself going down that path with more concrete information.
I wonder how much nitrate these mams are getting?

mammin tree2.JPG (165.4 KiB) Viewed 2093 times

mamm on cycad.JPG (97.25 KiB) Viewed 2093 times

[BryanT]

I wonder how much nitrate these mams are getting?
mammin tree2.JPG

mamm on cycad.JPG

Interesting pictures, Mike!
The conditions on the tree trunks must be quite good for so many cactus to grow on them, just like epiphyte cactus.
It reminds me of the growing media and conditions at one of the very good cactus and succulents nursery, where they have some of the most interesting and beautiful cactus and succulents. Most of their cactus growing media consisting of mostly organic material such as medium size wood chips and pine barks, very little/no fine organic materials, small amount of rough sands/gravels, with a bit of Controlled Release Fertilisers, very similar to orchid/epiphyte potting mix.
And, most of their cactus grow under shade-cloth only, getting lots of cold winter rain.
I still have few of the cactus and succulents from them in the original pot and potting mix. They seems to growing quite well, with a bit of fertilizer once a year.

[jerrytheplater]

Well, its been more than a day! But I have been reading the acidification thread Steve has as a sticky and see that is where the terms runoff water and slurry test etc come from. I also saw the link to the 2008 article "Cactus and Alkalinity" by Elton Roberts and Malcom Burleigh. Not finished with it yet.

While I'm grateful that I learned about the concept of acidification from Roberts' article, one of our members with a background in chemistry said that his knowledge of chemistry is suspect. Unfortunately I can't remember the source (this must've been from at least 10 years ago), but since you're a chemist, I'd be interested to get your take on this.
Steve, I'm not a chemist. I have a BS in Biology from Florida Institute of Technology back in 1977. I took 1 year of Gen Chem, 1 year of Organic Chem, and 1 year of Biochem, plus a quarter of Immunology. Did take a year of Plant Biology which I considered only slightly easier than Biochemistry. I worked in industry for 29 years using my chemistry in the electroplating department at work. That also involved operating the waste treatment system which was like a huge "Mr. Wizard" setup. Lots of pretty cool stuff. Showed me how much I didn't know.

My comments on the article and author: I thought it was well written and may have gone over the head of some of the readers in the society. But, he was talking about how he acidifies the water he uses on his cactus, and what he's learned from it.

Regarding pH of water and rebound:

When I said I'd use a batch of fertilizer I adjusted a bit too low in pH, that is because it would be only used one time. The next batch would be correct. I've learned not to trust the water that comes out of the tap. So I would test the next batch more carefully. And every time. We all get our water from drastically different sources: wells, reservoirs, RO filtration units....Purchased water is not constant in its properties throughout the year. Even wells can be affected by rainfall or lack thereof. Seasonal temps cause the reservoirs to turn over and mix twice a year. Around here the water companies can switch water sources at will.

Rebound: I had not heard of this term prior to reading it here on the forum. From reading that article I gather he is using this term to describe the effect of high alkalinity buffering water as it is being acidified. (What is considered "high"? Looks like in the 400 ppm CaCO3 range and up.) That does happen and I described it in my description of lowering the pH in that batch tank. But that was extremely concentrated and not at all like what anyone on this forum would ever see. Vigorous stirring will help to remove the CO2 formed when bicarbonates are acidified. If you don't, some of it will be converted back into bicarbonates by the remaining alkalinity. That is the buffering principle. You need to consume the buffer before you can drop the pH low enough.

What is happening in the pot? I really never considered that. Would I use the term "rebound" as used by Roberts to describe that? No. What would I call it? I don't know. Never thought of it.

See my comments in red above.

[jerrytheplater]

I wonder how much nitrate these mams are getting?
mammin tree2.JPG

mamm on cycad.JPG

Mike, do you know where these photos were taken? Great photos.

[ohugal]

I wonder how much nitrate these mams are getting?
mammin tree2.JPG

mamm on cycad.JPG

Mike, do you know where these photos were taken? Great photos.

Indeed! It would be interesting to perhaps publish them in our monthly cactus publication. Are there also close-ups?

[Steve Johnson]

I wonder how much nitrate these mams are getting?

Good question. Just to review, this brings up what iann said:

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. [my emphasis] If you want to start an interesting chain of thought in this context, it is worth noting that one consistent trend is for plants to prefer Ammonium ions in more acidic conditions and Nitrate ions in less acidic conditions. Another is that Nitrate ions tend to be preferred in hotter conditions.

Now I'll have to rethink the idea that the GH FloraMicro and FloraBloom will be a good substitute for the Dyna-Gro 7-7-7 that's done so well by my cacti over the course of 11 years. Here's a comparison of the 7-7-7 and the FloraMicro 5-0-1:

• Dyna-Gro 7% N broken down as 70% NO3, 30% NH4

• FloraMicro 5% N broken down as 94% NO3, 6% NH4

As the old saying goes, "if it ain't broke, don't fix it". Iann's comment (pointed out in my emphasis) makes a good argument in favor of continuing with the Dyna-Gro fert until what I have left in the gallon is used up. Good thing about having such a small collection is that I'll be good for another year or two. By the way -- IMHO Dyna-Gro has it right with the proportions of NO3 and NH4. You'll see the same thing in their Orchid Pro 7-8-6.

Ohugal, I realize this is a "long shot", but you may want to contact the Dyna-Gro people here:

https://dyna-gro.com/contact/

If they don't have a retail distributor in Europe, find out if one of the US retailers can ship to you (maybe Amazon US?). If the shipping cost isn't outrageous, I'll recommend their 7-8-6. An 8 fluid oz. jug goes for $12 here -- depending on the size of your collection and how often you fertilize, 1 jug could last you a good long time.

[ohugal]

Hi Steve,

I already have the GHE/TA. I can buy Dyna-Gro Orchid-Pro from a store in Norway. I could use the GHE/TA on other plants. What is the downside of having a more nitrate rich nitrogen? I read that plants prefer a more ammonium rich nitrogen in acidic conditions. Does that mean our cacti won’t take in the (more nitrate rich) nitrogen properly? Would this manifest in slow growth? The water we use is acidic, but as mentioned the soil isn’t necessarily so… Not trying to be contrary, I just want to be sure in case I purchase Dyna-Gro. I'm also going to double check the numbers on the GHE/TA FloraBloom and FloraMicro tomorrow. I just took a quick peek at the labels on the bottles and they differ from the numbers you just wrote down. Mine are not unbalanced such as yours, but tomorrow I will know for certain.

[jerrytheplater]

Aquatic plants used in aquariums preferentially take up ammonium. Pretty sure I read this in a book called "The Ecology of the Planted Aquarium" by Diana Walsted. This does not mean they can't use nitrate. It is just a little more difficult/metabolically expensive for them to use it. Potassium nitrate is used as a fertilizer in a huge percentage of planted aquariums. The ammonium comes from fish waste/pee.

[Steve Johnson]

Let's see if I'm explaining this well...

I already have the GHE/TA. I can buy Dyna-Gro Orchid-Pro from a store in Norway. I could use the GHE/TA on other plants. What is the downside of having a more nitrate rich nitrogen? I read that plants prefer a more ammonium rich nitrogen in acidic conditions. Does that mean our cacti won’t take in the (more nitrate rich) nitrogen properly? Would this manifest in slow growth? The water we use is acidic, but as mentioned the soil isn’t necessarily so… Not trying to be contrary, I just want to be sure in case I purchase Dyna-Gro. I'm also going to double check the numbers on the GHE/TA FloraBloom and FloraMicro tomorrow. I just took a quick peek at the labels on the bottles and they differ from the numbers you just wrote down. Mine are not unbalanced such as yours, but tomorrow I will know for certain.

From iann, "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" -- I take it to mean that we'd be stuck in a guess right/guess wrong situation. Guess right on a fert that largely favors either NO3 or NH4, and the cacti do well. Guess wrong, and they eventually suffer. The FloraMicro I was considering means that I'd be taking a chance on guessing right -- as you said, very unbalanced in favor of NO3. I'd rather not guess, and while the Dyna-Gro is still somewhat unbalanced between NO3 and NH4, 11 years of good growing experience with the 7-7-7 tells me that it's quite acceptable. In fact, the Orchid-Pro may be better at "covering the bases" in terms of NO3 and NH4 for all of the cactus species you're growing. If the N in the TA FloraMicro you're considering strikes a balance that's similar to the 7-8-6, I think you should be fine. If not, go with the 7-8-6 -- only downside there is determining the correct amount of Potassium sulfate to supplement the K in your watering solution. (And yes, your cacti could use the Sulfur in Potassium sulfate. There's not nearly enough S in the 7-8-6 by itself.) If you need any assistance with that, I might be able to help.

P.S. Are the labels on your TA FloraMicro and FloraBloom reporting elemental P and K or P2O5 and K2O?

[MikeInOz]

I wonder how much nitrate these mams are getting?
mammin tree2.JPG

mamm on cycad.JPG

Mike, do you know where these photos were taken? Great photos.

Mexico would be my best guess.

[MikeInOz]

I wonder how much nitrate these mams are getting?
mammin tree2.JPG

mamm on cycad.JPG

Mike, do you know where these photos were taken? Great photos.

Indeed! It would be interesting to perhaps publish them in our monthly cactus publication. Are there also close-ups?

There are a few more. Just type in cactus in tree or mammillaria in tree. Most seem to be from Oaxaca

[MikeInOz]

Another is that Nitrate ions tend to be preferred in hotter conditions.

[/quote]

The other way round I believe. A level of ammonium which is completely safe during the bright and warm summer can be quite toxic in winter due to the lack of photosynthate production leading to ammonium toxicity. Traditionally, nitrate is seen as a '' low temp, low light winter'' fertilizer of preference in greenhouse production. ( Note.. nitrate must be reduced to ammonium inside the plant before it can be used. Without molybdenum, nitrate it can build up in plants so it must not be left out of fertilizers)
You mentioned that hydroponics uses mainly nitrate. That is simply because the media used in hydroponics has very low CEC (or none) and the risk of ammonium toxicity is much higher.

[jerrytheplater]

I wonder how much nitrate these mams are getting?
mammin tree2.JPG

mamm on cycad.JPG

Mike, do you know where these photos were taken? Great photos.

Mexico would be my best guess.

Thanks! I've seen photos of Mamm's growing right near water seeps with Pinguicula carnivorous plants. Also in Mexico.

[Steve Johnson]

Ooh, my head hurts!

You mentioned that hydroponics uses mainly nitrate. That is simply because the media used in hydroponics has very low CEC (or none) and the risk of ammonium toxicity is much higher.

It's good to get the terminology straight, so I should make the distinction between soil-less mixes (in other words, no actual dirt in the mix) and hydroponic mixes such as my pumice and granite gravel mix. Do you think the amount of NH4 in the Dyna-Gro 7-7-7 could be a problem and I don't know it? If so, then the GH FloraMicro's higher NO3 may actually be better. Unfortunately I wouldn't know what to look for if there have been any negative long-term effects on my cacti with 11 years of the 7-7-7's NH4. Bear in mind that I fertilize every time I water, but only in the spring/summer growing season here in SoCal. For the 23 cacti that do get occasional watering in fall and winter (sips for most, soaks for a few), it's distilled water or rainwater and nothing more. Before I get ready for spring, what's your best recommendation?