The Cal-Mag of my dreams?

[jerrytheplater]

Steve

Thanks for the reminder about SDK1's posts. I did read them when they were posted and responded but did not follow up on Mike's book. I will see if I can borrow a copy from the library. I just went back and read the whole "When Cactus Turn Yellow" thread where MikeinOz gives his rationale for his ratio. SDK1 also went into plant tissue analysis. This is making more sense to me.

In the chart Mike gave, converting the tissue analysis to a elemental NPK ratio, you get for leaves: 1-0.26-1.66. For flowers you get: 1-0.17-1.62. In the Cholla stem analysis you get the following N:P ratios: 1:0.067 to 1:0.125. That is some pretty good evidence for lower P in fertilizers since plant tissues don't show high P levels compared to N and K.

MikeinOz said: "too much P can interfere with trace element uptake especially iron and it can reduce flowering. Too much K is very rare and usually not an issue."

So, now to see what "too much P" is. Maybe its in the book Mike supplied. When is iron uptake impaired?

[MikeInOz]

I'd like to see some references that show what the effects of over feeding with P causes. Do you happen to know of any? I need to go over those articles I posted up last week. Might be something in there.

Jerry, given that Phalaenopsis orchids are probably the most studied ornamental greenhouse crop, there is a lot of literature on their fertilization out there. Google scholar is the place to start reading. Too much P can lead to reduced growth, reduced flowering and interference with trace element uptake as well as outright toxicity if the dose is over the top....

[MikeInOz]

In the meantime, here's a question for Mike -- when it comes to P in the proper NPK balance, is not enough better than too much?

Steve, all I can say is that one is probably as bad as the other.

[MrXeric]

A number of years ago, I saw a very interesting article online from a noted cactus expert discussing the dangers of overfeeding. His article included photographic examples of abnormal stem growth on cacti caused by overfeeding, with descriptions of what the abnormalities were.

Probably not the articles you were talking about, but your description reminded me of these:
https://xerophilia.ro/wp-content/upload ... %3A.493789

https://xerophilia.ro/wp-content/upload ... 441%2C0%5D

They are both by the same author, but he doesn't go into detail on formulation. The first he just points out what he considers over-fertilization to look like, focusing primarily on abnormal flowering habits, while the second he just compares two approaches to cultivation with different preferred aesthetical outcomes, well-fertilized (what he calls "florist" plants) vs hard-grown, habitat-like plants.

[MikeInOz]

So, now to see what "too much P" is. Maybe its in the book Mike supplied. When is iron uptake impaired?

I would have to look it up but I think it says a P/N ratio of something like 0.3 is perfectly ok for most flowering plants. That ratio would quickly kill a lot of Australian plants sensitive to P! But I would say 0.4 would be more than enough for anything.

[Steve Johnson]

All very good information -- thanks, Jerry and Mike!

A number of years ago, I saw a very interesting article online from a noted cactus expert discussing the dangers of overfeeding. His article included photographic examples of abnormal stem growth on cacti caused by overfeeding, with descriptions of what the abnormalities were.

Probably not the articles you were talking about, but your description reminded me of these:
https://xerophilia.ro/wp-content/upload ... %3A.493789

https://xerophilia.ro/wp-content/upload ... 441%2C0%5D

They are both by the same author, but he doesn't go into detail on formulation. The first he just points out what he considers over-fertilization to look like, focusing primarily on abnormal flowering habits, while the second he just compares two approaches to cultivation with different preferred aesthetical outcomes, well-fertilized (what he calls "florist" plants) vs hard-grown, habitat-like plants.

Actually, those are the articles, and unfortunately not the information I was hoping to find. Even more unfortunate -- xerophilia.ro's certificate is expired, and I wouldn't trust a Romanian website with an expired certificate:

Xerophilia_security_risk.jpg (25.65 KiB) Viewed 10124 times

My computer clock is set to the right time, so that's a no-go. Too bad, because I wanted to go through those articles anyway. Abnormal flowering habits? That sounds like a symptom of excessive P in the ferts the growers were using.

[keith]

Excessive phosphorus is a acid reaction ? Triple phosphate is made with acid ?

"Triple phosphate is a mineral fertilizer containing a high amount of phosphorous. This fertilizer is produced from phosphate rock via the addition of phosphoric acid. It contains more than twice the phosphorous content of single superphosphate"

Also Africa is deficient in phosphorus at least I read that, makes it hard to grow crops. So I would guess Mesembs don't need much phosphorus ??

[Steve Johnson]

Also Africa is deficient in phosphorus at least I read that, makes it hard to grow crops. So I would guess Mesembs don't need much phosphorus ??

I would say that's true for cacti and succulents in general.

Here'a an item of interest I found called Master gardeners: Desert soils and fertilizer by Lake Havasu City Master Gardener Steve Gissendanner (source https://apnews.com/article/5e06475955f8 ... 2d491782c6). I'll pull out a few salient quotes:

• "Desert soils are very different from soil that you find in other parts of the country. Organic matter, nitrogen, and phosphorus are lacking in our desert soils. These three components are necessary for proper plant growth, and their low availability makes growing plants here a challenge, unless they are desert natives that have adapted to our soil conditions."

• "Desert soils are short of organic matter that comes from decaying plant material; one of the reasons why desert soils lack the dark browns and blacks of high productive soils. A general lack of natural vegetation, coupled with dry windy conditions, prevents organic matter from accumulating in our native soils."

• "Desert soils are also low in nitrogen; a component that makes plants grow. Nitrogen is the most abundant element in our planet’s atmosphere. However, Nitrogen in its gaseous form (N2) can’t be used by most living things. It has to be converted, or “fixed,” to a more usable form either biologically, through lightning activity, or synthetically through inorganic fertilizer production.
  
  "Desert soils are often low in phosphorus as well. Phosphorus comes mainly from rocks, but most phosphorus is locked up in sediments and rocks, making it unavailable to plants." [My emphasis.]

This makes a good argument in favor of the fact that even when they're being grown under cultivation, desert cacti need P that's substantially lower than N. Once again, benchmarking N at a constant of 1, P below 0.2 is too low, P above 0.5 is too high, and a range in between is just right. What I just said might not apply only to cacti and succulents, although I don't know if it's true about nonxeric ornamental plants since I have no experience growing them. Maybe higher P is required for crop production, but we're not growing crops here, are we?

[jerrytheplater]

Excessive phosphorus is a acid reaction ? Triple phosphate is made with acid ?

"Triple phosphate is a mineral fertilizer containing a high amount of phosphorous. This fertilizer is produced from phosphate rock via the addition of phosphoric acid. It contains more than twice the phosphorous content of single superphosphate"

Also Africa is deficient in phosphorus at least I read that, makes it hard to grow crops. So I would guess Mesembs don't need much phosphorus ??

Keith, just found a neat article: Sources of Phosphorous for Plants: Past, Present, and Future. http://www.ipni.net/publication/betterc ... %20p17.pdf

[Steve Johnson]

Probably not the articles you were talking about, but your description reminded me of these:
https://xerophilia.ro/wp-content/upload ... %3A.493789

https://xerophilia.ro/wp-content/upload ... 441%2C0%5D

They are both by the same author, but he doesn't go into detail on formulation. The first he just points out what he considers over-fertilization to look like, focusing primarily on abnormal flowering habits, while the second he just compares two approaches to cultivation with different preferred aesthetical outcomes, well-fertilized (what he calls "florist" plants) vs hard-grown, habitat-like plants.

Good news -- I found both articles on cactuspro.com, so I now have the PDFs archived on my computer. Once I go through them in depth, I'll find out if they have any relevance to our discussions regarding the negative effects of excessive P on cacti. Note to everyone: When I snagged the PDFs, I found out that the Xerophilia website is gone, so get all of the Xerophilia journal issues on your computers while you can. I'll post an advisory on the General forum.

Mike, if you have a chance, go here...

https://www.cactuspro.com/biblio_fichie ... 018-23.pdf

...and read through "Over-fertilization, a determining factor in the dynamics of aberrant growth and flowering in Cactaceae" starting on page 81. Your take on that article would be fascinating, so please let us know what your thoughts are. While you're at it, you may want to check out the special issue called "The Stone Eaters":

https://www.cactuspro.com/biblio_fichie ... Eaters.pdf

Any thoughts on that article too?

[MikeInOz]

Probably not the articles you were talking about, but your description reminded me of these:
https://xerophilia.ro/wp-content/upload ... %3A.493789

https://xerophilia.ro/wp-content/upload ... 441%2C0%5D

They are both by the same author, but he doesn't go into detail on formulation. The first he just points out what he considers over-fertilization to look like, focusing primarily on abnormal flowering habits, while the second he just compares two approaches to cultivation with different preferred aesthetical outcomes, well-fertilized (what he calls "florist" plants) vs hard-grown, habitat-like plants.

Good news -- I found both articles on cactuspro.com, so I now have the PDFs archived on my computer. Once I go through them in depth, I'll find out if they have any relevance to our discussions regarding the negative effects of excessive P on cacti. Note to everyone: When I snagged the PDFs, I found out that the Xerophilia website is gone, so get all of the Xerophilia journal issues on your computers while you can. I'll post an advisory on the General forum.

Mike, if you have a chance, go here...

https://www.cactuspro.com/biblio_fichie ... 018-23.pdf

...and read through "Over-fertilization, a determining factor in the dynamics of aberrant growth and flowering in Cactaceae" starting on page 81. Your take on that article would be fascinating, so please let us know what your thoughts are. While you're at it, you may want to check out the special issue called "The Stone Eaters":

https://www.cactuspro.com/biblio_fichie ... Eaters.pdf

Any thoughts on that article too?

I only skimmed the article Steve because I have to surrender the computer, but I have found a couple of speculative nonsense statements. For example, the Astro with lots of flower buds. It obviously has not been ''over fertilized'' looking at the plant itself, which appears normal in every way
- not bloated - not stretched - a good even covering of scales and areoles. So clearly there is another reason for all the flower buds. Another statement where ''this is the way Mammillaria schumanii is supposed to look.'' Says who? I certainly would not want mine to look like it's close to death. But maybe that's just me.....

[jerrytheplater]

So, now to see what "too much P" is. Maybe its in the book Mike supplied. When is iron uptake impaired?

I would have to look it up but I think it says a P/N ratio of something like 0.3 is perfectly ok for most flowering plants. That ratio would quickly kill a lot of Australian plants sensitive to P! But I would say 0.4 would be more than enough for anything.

Mike, here is an article taken from Better Crops With Plant Food, A Publication of the International Plant Nutrition Institute (IPNI) that is food for thought regarding the high limit of P fertilization.

The article is called "Measuring Crop-Available Phosphorous". It discusses the need to correlate plant response to Phosphorous and the soil test procedure used to test for the P in the soil. See especially "Figure 1. Relationship between soil-test P and relative yield of corn and soybean across several years of experiments at Iowa locations."

That figure shows an optimum soil P level down in the 20 ppm range for both crops to give 90-100% relative yield. But each show continued 90-100% relative yield even out to 70 ppm P in the soil. Nothing is said about P content in the plants themselves. Nothing is said about harm to the crop, only the unnecessary extra expense to overfertilize or the possible loss of the P to the environment causing eutrophication of local waterways.

http://www.ipni.net/publication/betterc ... %20p13.pdf

[Steve Johnson]

I only skimmed the article Steve because I have to surrender the computer, but I have found a couple of speculative nonsense statements. For example, the Astro with lots of flower buds. It obviously has not been ''over fertilized'' looking at the plant itself, which appears normal in every way
- not bloated - not stretched - a good even covering of scales and areoles. So clearly there is another reason for all the flower buds. Another statement where ''this is the way Mammillaria schumanii is supposed to look.'' Says who? I certainly would not want mine to look like it's close to death. But maybe that's just me.....

Hi Mike,

Certainly not a high priority, but when you can go through those articles at your leisure, I think you'll concur with a couple of things I noticed:

• A dismissive attitude on the part of Dag Panco toward cacti that are properly fed by growers who know what they're doing. I wouldn't want my cacti looking like they're on death's door either.

• Neither author seems to know much (if anything) about the role of nutrients available to cacti under cultivation when growers use ferts that are well-balanced and include a full spectrum of all nutrients.

With respect to Mr. Panco, I do see examples of what seem to be abnormal growth in his article. What I don't see are precise descriptions of what caused the abnormalities -- "a plant influenced by an excess of fertilizers" tells us nothing. What I also don't see -- examples of cacti being grown with excessive P in the fert. Since your eyes are much better-trained than mine, maybe you do. If so, point me to the pages where you see them, and I can pull the photos out from the PDF for reference.

Why am I making such a big deal out of all this? Here's why -- from Part 1 of my Fertilizers Explained presentation:

NPK ratio

This ratio determines whether you have well-balanced or unbalanced proportions of N, P, and K in your fert. The ideal NPK ratio for cacti and succulents is 1:0.4:1.1-1.7. Contrary to what you may have heard or read elsewhere, high-Phosphorus ferts should be avoided -- when P is higher than N, poor root growth and abnormal stem growth will be the eventual consequence of the plant's longterm exposure to a high-P fert.

I'm not satisfied with that because I don't think it's specific enough. Besides, "show and tell" would be better than making do with simply "tell" -- if I can include photographic examples of what cacti exhibiting the signs of excessive P look like, growers will know what to look for in case their cacti have those problems. And if they do, they can look for a lower-P fert to correct the situation before the problems become even more of a problem over time.

[MikeInOz]

That figure shows an optimum soil P level down in the 20 ppm range for both crops to give 90-100% relative yield. But each show continued 90-100% relative yield even out to 70 ppm P in the soil.

But is that soluble P or insoluble P? In other words is it available to the plants or just the total soil P content?
Also, for that crop, the 20 to 70 ppm range could be the optimum range? There will be a level where yield will start to decline as P increases but I have no idea what that might be in that situation.

[MikeInOz]

I only skimmed the article Steve because I have to surrender the computer, but I have found a couple of speculative nonsense statements. For example, the Astro with lots of flower buds. It obviously has not been ''over fertilized'' looking at the plant itself, which appears normal in every way
- not bloated - not stretched - a good even covering of scales and areoles. So clearly there is another reason for all the flower buds. Another statement where ''this is the way Mammillaria schumanii is supposed to look.'' Says who? I certainly would not want mine to look like it's close to death. But maybe that's just me.....

Hi Mike,

Certainly not a high priority, but when you can go through those articles at your leisure, I think you'll concur with a couple of things I noticed:

• A dismissive attitude on the part of Dag Panco toward cacti that are properly fed by growers who know what they're doing. I wouldn't want my cacti looking like they're on death's door either.

• Neither author seems to know much (if anything) about the role of nutrients available to cacti under cultivation when growers use ferts that are well-balanced and include a full spectrum of all nutrients.

With respect to Mr. Panco, I do see examples of what seem to be abnormal growth in his article. What I don't see are precise descriptions of what caused the abnormalities -- "a plant influenced by an excess of fertilizers" tells us nothing. What I also don't see -- examples of cacti being grown with excessive P in the fert. Since your eyes are much better-trained than mine, maybe you do. If so, point me to the pages where you see them, and I can pull the photos out from the PDF for reference.

Why am I making such a big deal out of all this? Here's why -- from Part 1 of my Fertilizers Explained presentation:

NPK ratio

This ratio determines whether you have well-balanced or unbalanced proportions of N, P, and K in your fert. The ideal NPK ratio for cacti and succulents is 1:0.4:1.1-1.7. Contrary to what you may have heard or read elsewhere, high-Phosphorus ferts should be avoided -- when P is higher than N, poor root growth and abnormal stem growth will be the eventual consequence of the plant's longterm exposure to a high-P fert.

I'm not satisfied with that because I don't think it's specific enough. Besides, "show and tell" would be better than making do with simply "tell" -- if I can include photographic examples of what cacti exhibiting the signs of excessive P look like, growers will know what to look for in case their cacti have those problems. And if they do, they can look for a lower-P fert to correct the situation before the problems become even more of a problem over time.

Steve, I just wrote a long reply to this and when I finished the whole thing was wiped so I will try again later when my anger subsides...