Is gypsum an effective top dressing for supplementing calcium in a coco DTW system?

beta · Nov 15, 2018

I'm trying to supplement calcium for a couple particularly hungry cultivars. Will top dressing them with agriculutural Gypsum (Calcium Sulfate Dihydrate) work? I'm worried the calcium won't be soluble enough and will rinse out before it's available.

Thanks!

BillFarthing · Nov 15, 2018

Hi Beta,

Commercially, coir is buffered with calcium nitrate:
https://www.maximumyield.com/buffer...xchange-capacity-in-coco-growing-media/2/1318

I think moist coco/gypsum would replace the sodium and potassium ions eventually and run off from the medium wouldn't be a problem.

Only Ornamental · Nov 19, 2018

This so called ion-exchange of K and Na against calcium is a very common effect and results in well bound calcium ions. Furthermore, the fact that gypsum is poorly soluble (slow release) gives it enough time to perform this task and not just run straight through the coir. Though, IDK if the solubility is fast enough to meet plant requirements. This will likely depend on the gypsum quality and environment: fineness/coarseness, crystal modification (purity of gypsum, method of preparation etc.), humidity, presence of other ions (fertiliser composition)...
Just try it out

.

beta · Nov 19, 2018

Only Ornamental said:
This so called ion-exchange of K and Na against calcium is a very common effect and results in well bound calcium ions. Furthermore, the fact that gypsum is poorly soluble (slow release) gives it enough time to perform this task and not just run straight through the coir. Though, IDK if the solubility is fast enough to meet plant requirements. This will likely depend on the gypsum quality and environment: fineness/coarseness, crystal modification (purity of gypsum, method of preparation etc.), humidity, presence of other ions (fertiliser composition)...
Just try it out .

I was hoping I'd hear from you, thanks for the feedback!

It's my understanding that the dihydrate form of calcium sulfate is more or less water soluble. Is that your understanding as well? When I add it to water it seems to dissolve fully.

This is the exact one I'm using, fwiw. It claims to be '100% water soluble'.

paradoxlost · Nov 19, 2018

Only Ornamental said:
This so called ion-exchange of K and Na against calcium is a very common effect and results in well bound calcium ions. Furthermore, the fact that gypsum is poorly soluble (slow release) gives it enough time to perform this task and not just run straight through the coir. Though, IDK if the solubility is fast enough to meet plant requirements. This will likely depend on the gypsum quality and environment: fineness/coarseness, crystal modification (purity of gypsum, method of preparation etc.), humidity, presence of other ions (fertiliser composition)...
Just try it out .

Isn't gypsum the first or second most soluble calcium salt? Isn't it like CaCl2> Lime = Gypsum > CaNO3 > CaPO4

Only Ornamental · Nov 21, 2018

My pleasure!

Pure calcium sulfate dihydrate is indeed fully water soluble, just not very good and not very fast.

Ibechillin · Nov 21, 2018

With soluble aminos added the calcium availability from gypsum can can be increased considerably as well, "Thousands of times faster" is how Harley Smith worded it.

beta · Nov 21, 2018

Ibechillin said:
With soluble aminos added the calcium availability from gypsum can can be increased considerably as well, "Thousands to millions of times faster" is how Harey Smith worded it.

That is interesting - Can you link me to where you learned this?

beta · Nov 21, 2018

I just ran across this semi-related video, it gets interesting around the 5 minute mark:

[YOUTUBEIF]kIJ3XL5hCwM[/YOUTUBEIF]

Found it via:
https://calciumproducts.com/ag-products/product-so4/item/132-turf-gypsum-quality-calcium-sulfur

What he refers to simply as 'gypsum' is the dihydrate form I'm using (vs the anhydrate form).

Ibechillin · Nov 21, 2018

This is the one, its a great article.

https://www.maximumyield.com/what-to-do-about-powdery-mildew/2/1400

Here are some more good articles by him:

http://npk-industries.com/resources.html

beta · Nov 21, 2018

Ibechillin said:
This is the one, its a great article.

https://www.maximumyield.com/what-to-do-about-powdery-mildew/2/1400

Here are some more good articles by him:

https://npk-industries.com/resources.html

Awesome, thank you! Here's the relevant bit:

After years of research and experimentation in plant physiology, microbiology and nutrition, the pieces finally came together. Amino acids were the key. My well water is loaded with calcium and magnesium carbonate, and lime scale used to turn my reservoirs into rock gardens.

But when I started experimenting with an amino acid blend I received from a vitamin manufacturer, there was no more lime scale. So where did all of that extra calcium go? Into the plants. I learned that certain amino acids stimulate root cells to open up calcium ion channels, allowing the plants to take up calcium thousands of times faster than simple osmosis.

Wow! That is some very interesting info if true. Does anyone know if this is accepted scientific consensus? I don't know how evidence-based Harley Smith's system is, though I do admit he sounds like he knows what he's talking about to a lay person like me.

beta · Nov 21, 2018

I found some research to support what he's saying:

Calcium Chelated with Amino Acids Improves Quality and Postharvest Life of Lisianthus (Eustoma grandiflorum cv. Cinderella Lime)
http://hortsci.ashspublications.org/content/50/9/1394.full

The results of this study confirmed the effectiveness of calcium amino acid chelates in increasing calcium absorption and shoot fresh and dry mass of lisianthus (‘Cinderella Lime’). These effects were more favorable than those exerted by CaCl2. Since calcium amino acid chelates could preserve lisianthus cut flowers, they can be used as an appropriate source of calcium compared with CaCl2 to improve the vase life of lisianthus cut flowers. Simultaneous effects of calcium and amino acids were found to be responsible for the mentioned benefits of calcium amino acid chelates. According to the obtained results, calcium-lysine is recommended as a preferable source of calcium instead of CaCl2.

Only Ornamental · Nov 23, 2018

AA chelated calcium, most commonly in the form of calcium bisglycinate, has often no charge or even a negative one. As such, there is no interaction with soil/coir particles and it drains away quickly. Super as a permanent drip-irrigation or a quick boost, not so much as a depot.
Such chelates can be produced easily at home when mixing aminos with calcium oxide or hydroxide

.

clearheaded · Nov 23, 2018

best would be to mix into medium. top dressing you likely will end up with a plaster like layer on the top of your pots depending on how much you use. so if can work it in to the top couple inches, then maybe mix small amount with a watering aswell.

I would go easy at first just because as a top dress u may end up making it difficult to water until mix it in a bit better. but best if just add to ur coco. and be sure ur PH is all good aswell as it will make it a little harder to get higher or lower PH in your medium.

obviously not the only source of calcium but will def help buffer and add calcium. yes its not fast as cal nit but thats part of why its good!

FJ2000 · Nov 23, 2018

clearheaded said:
best would be to mix into medium. top dressing you likely will end up with a plaster like layer on the top of your pots depending on how much you use. so if can work it in to the top couple inches, then maybe mix small amount with a watering aswell.

I would go easy at first just because as a top dress u may end up making it difficult to water until mix it in a bit better. but best if just add to ur coco. and be sure ur PH is all good aswell as it will make it a little harder to get higher or lower PH in your medium.

obviously not the only source of calcium but will def help buffer and add calcium. yes its not fast as cal nit but thats part of why its good!

Does the anhydrous form prevent that “plaster” situation? Was looking for a way of adding Ca to coco mid grow without adding the N from something like a calmag supplement. Great info, thanks
FJ

beta · Nov 24, 2018

FJ2000 said:
Does the anhydrous form prevent that “plaster” situation? Was looking for a way of adding Ca to coco mid grow without adding the N from something like a calmag supplement. Great info, thanks
FJ

Yeah, I've tried both adding it to water and top dressing it + watering it in and in both cases it dissolves immediately.

Guest · Nov 26, 2018

beta · Nov 27, 2018

So I've been watering it in top dressed at a rate of about 1 tsp / gal of medium once per week, and I'm seeing great results! I know Ca is one of those things that takes a long time to 'see', but after a couple weeks the plants seem happier, the petioles are 'crisper' when I pluck them off and the stems seem more waxy / dense when I cut through them. Stems feel more rigid / thick and I can't get branches to easily 'peel' off touchy cultivars like Original Diesel anymore.

I think this fixed my problem!

caljim · Nov 27, 2018

I have been dissolving gypsum and adding it to my feeds along with aminos from Kelp 4 Less and my plants are very happy about it. About 50 to 100ppm. Growing in coir, dtw. Not very scientific, but the proof is in the pudding.

LadyGuru · Nov 27, 2018

Yes, gypsum will work. Get the finest possible.

Is gypsum an effective top dressing for supplementing calcium in a coco DTW system?

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