[Skyver]

Hi, in the UK there is a nute co called Vitalink. They use phosphites instead of phosphates in there grow/bloom feeds. Are you guys saying that it shouldn't be used this way?

[zenoonez]

Whole thread on it. https://www.icmag.com/ic/showthread....ight=phosphite

[zenoonez]

Originally Posted by Guest

What? Information is information, if people choose to act like little children calling one another names it doesn't devalue the info...

[spurr]

Originally Posted by Skyver

Hi, in the UK there is a nute co called Vitalink. They use phosphites instead of phosphates in there grow/bloom feeds. Are you guys saying that it shouldn't be used this way?

This topic blew up in the other thread zenoonez posted, there was unfriendly posts between some members (including myself) in the last pages of that thread, that is why Guest posted the cop emoticon.

I don't want this thread to turn into what happened in the last thread, so I will give you the CliffNotes on what phosphates can do. This will be my only response in this thread, and I will provide only the facts.

If Guest feels he needs to lock this thread, it's fine by me :

--------------------------

Exactly, phosphites (Phi) are a very poor source of P, and they cannot be used as the primary source of P. If a plant is low on P, and Phi is provided, then the Phi is most often deleterious to the plant. Also, if a plant uptakes Phi, it hinders the uptake of the regular chem fert source of P: phosphates (Pi).

If a plant uptakes Phi, then the Phi stays as Phi in the plant tissue, and does not provide P because all known/studied plants do not have an enzyme that can oxidize Phi into Pi for P. Phi must be converted (oxidized by bacteria) into Pi before it is taken in the plant, to provide P to the plant.

The process of oxidization of Phi into Pi by bacteria, so the plant can use Pi for P, takes a while. It takes week(s) depending upon the amount/type of microbes present. Also, if there is Pi or "dissolved organic phosphorous" (DOP) available, the bacteria will first use the Pi and DOP as energy, before they convert Phi into Pi, allowing the plant get use the converted Pi as P...thus the process is even slower if Phi is co-applied with Pi.

If Phi is used as the only P source then the plant will become P deficient in a short time and will not be healthy.

Phi is a fungicide, not a direct source for P, because for Phi to provide P bacteria must first break it down into Pi (i.e. the normal source of P from chem ferts). Thus, a grower should just provide regular Pi fertilizer for P, not Phi, because Phi needs to be broken down into Pi before it can provide P. Using Phi for P is a very poor idea by VitaLink because Phi doesn't provide P directly, it must first be broken down into Pi, and that takes week(s).

Any company that is selling Phi as a direct P source, esp. if they claim it's better than Pi (normal phosphate ferts), is selling snake oil, because Phi is a very poor source of P. Any company selling Phi as a direct and superior P source are a bunch of idiots.

Along with all the references I posted above, here are two other good, and very current reviews:

1. "Phosphite (phosphorous acid): Fungicide, fertilizer or bio-stimulator?"
Hoang Thi Bich THAO, Takeo YAMAKAW
Soil Science & Plant Nutrition, Volume 55, Issue 2, pages 228–234, April 2009
https://onlinelibrary.wiley.com/doi/1...365.x/abstract

Abstract

Phosphite (Phi), a reduced form of phosphate (Pi), is widely marketed as either a fungicide or fertilizer or sometimes as a biostimulant. This is confusing for both distributors and growers.

The present paper explores data from various studies to clarify that Phi does not [directly or efficiently; edit spurr] provide plant P nutrition and thus cannot complement or substitute Pi at any rate. In addition, Phi itself does not have any beneficial effect on the growth of healthy plants [except as a poor SAR inducer for some plants; edit spurr], regardless of whether it is applied alone or in combination with Pi at different ratios or different rates.

The effect of Phi on plants is not consistent, but is strongly dependent on the Pi status of the plants. In most cases, the deleterious effect of Phi is evident in Pi-starved, but not Pi-sufficient, plants. Plants fertilized with Pi allowing for approximately 80–90% of its maximum growth might still be at risk of the effect. This negative effect becomes more pronounced under more seriously Pi-deficient conditions.

Although a number of studies have shown positive crop responses to Phi, these responses are likely to be attributable to the suppression of plant diseases by Phi and/or to Pi formed from oxidation of Phi by microbes. In addition, indirectly providing P by Phi-to-Pi oxidation is not an effective means of supplying P to plants compared with Pi fertilizer.

An understanding of these issues will aid the right selection of fertilizer as well as minimize the harmful effects of Phi use on crops.

2. "Understanding the Phosphonate Products"
Department of Crop and Soil Sciences - Cooperative Extension
Prepared by Peter Landschoot, Professor and Joshua Cook, Dept. of Crop and Soil Sciences, The Pennsylvania State University
https://www.scribd.com/doc/20206361/U...onate-Products

Phosphonates were first investigated as fertilizers in Germany and the U.S. during the 1930s and 40s. At that time, agricultural officials were concerned that war activities would disrupt vital shipments of rock phosphate for fertilizer production, so alternative sources of fertilizer phosphorus were explored (6).

Results of studies conducted in both countries demonstrated that phosponates were not effective substitutes for phosphate fertilizer. USDA scientists found that yields of legumes and grasses treated with calcium phosphite were lower than phosphate-treated plants, and in most cases, lower than controls plants receiving no phosphorus. However, a second crop seeded into the same soils that were treated with calcium phosphite showed improved yields. The authors attributed the delayed phosphorus response to the conversion of phosphite to phosphate in the soil (9).Subsequent research revealed that phosphite could be converted to phosphate primarily by soil-borne bacteria, but that these bacteria would not use phosphite until most phosphate was depleted (1).

Based on the results of these studies, phosphonate fertilizer was viewed as an inefficient and costly means of supplying phosphorus to plants and scientists eventually lost interest in this compound as a phosphorus fertilizer.

Despite previous research findings, phosphonate compounds are marketed by some companies as a source of phosphorus and potassium fertilizer.

The grass on the left got Pi as a P source, and the grass on the right got Phi as a P source:

Originally Posted by zenoonez

What? Information is information, if people choose to act like little children calling one another names it doesn't devalue the info...

No, but it WILL get the thread closed.

[zenoonez]

Originally Posted by Guest

No, but it WILL get the thread closed.

I have been here long enough to know that. I was just wondering why the cop made an appearance here. Lol. Too bad we can't just all get along. Lol.

[spurr]

I have had a few interactions with Guest, and IMO he is one of the best mods I have ever come across at any forum. I think he didn't mean anything against you, or I, he was just letting people know to behave. I think he had the best intentions with the cop emoticon at heart, I think he is very fair.

If it were a few other mods, then I could see your point, but after my interactions with Guest I think he didn't mean anything rude or threatening by it, to you, or to me.

[grapeman]

How old are you?

I neither started this or the other thread regarding phosphites. I never contended that it was either the phosphites or K were resulting in results that myself and others have seen using pure flowers.

The only fact I stated was that since using phosphites in the form of nutri-phite K (all foliar) in my vineyards (for almost 20 years), my P levels have consistently remained where I want to maintain them and I have been able to reduce the use of heavy phos acid applications to the soil. Major reductions. Saving money reductions. And I have validated these P levels with petiole analysis.

Some growers, either here or on other crops would find that of interest since high applications of phos acid in the soil have been shown to be detrimental to microbial life in the soil.

The reason I ask how old you are is obvious in your posts and your new sig.

[organicsquirrel]

I read the other thread and I think both sides have some pretty good arguments and I bet anybody who read that thread LEARNED some good shit about nutrients and soil. I have a special text file where I save really good info I read and I've taken several things from spurr's posts in the other phosphite thread and many of his other posts. His knowledge of chemical processes involving plants is far beyond mine and many others.

I think using somebody in a negative light in your sig is taking it a little too far. Keep it civil, boards are a good place for discussions but not arguments. I'm no mod but you oughta take the grapeman out of your sig, but I like you linking the thread so more people can read up on all of this.

In the end I think you are both right I think, spurr, that you are right and that the phosphites do not (at least in any convenient time frame) provide a good source of P. It's possible that some other process is going on in grapeman's fields involving possibly the phosphites, possibly involving any other thing in it, that is positively affecting his P levels. It sounds to me like in a large scale commercial operation such as grapeman's there are many variables and he is unable to run a full on 'scientific'-type blind experiment that might isolate the phosphites with his grapes. I think that until this goes to that point neither of you are really arguing about the same thing, and I hate to see people get upset over something silly like, "apples are tart", "NO! Oranges are orange!", and so on...