Nice to meet you all from Indonesia (and an overview on my plant journey)

[Steve Johnson]

Noted! Although there is something quite 'funny': granular gypsum... sounds alien to me. Maybe because I never see it being sold here or am I missing something? All I know is that locally, gypsum applied as fertilizers or soil conditioner almost always (judging by there is a minuscule chance of granular gypsum existing in Indonesia) in powder form. Though, if this turns to be just right, gypsum are also used to make sculptures for kindergarten/preschool projects in which I think if I can crush those untouched gypsum statues, that'll do the trick (again, if that turns to be right; do granular gypsum have additional ingredient to stabilize their form?).

Worry not, I'm doing my research at the moment, and it seems India makes a lot of them. My, this means if I have to get those, I have to import them.

India, you say? Check this out:

https://www.amazon.in/AgroGyp-Agricultu ... r=8-7&th=1

https://www.amazon.in/AgroGyp-Agricultu ... 196&sr=8-6

If you don't already have an Amazon account, now would be a good time to get one. Before you do, find out if Amazon India will ship to Indonesia. If so (and import duties aren't outrageously expensive), you'll get exactly what you need. Either product works, although I'm leaning toward the one in the first link. Good luck!

[Wiandry Adi]

India, you say? Check this out:

https://www.amazon.in/AgroGyp-Agricultu ... r=8-7&th=1

https://www.amazon.in/AgroGyp-Agricultu ... 196&sr=8-6

If you don't already have an Amazon account, now would be a good time to get one. Before you do, find out if Amazon India will ship to Indonesia. If so (and import duties aren't outrageously expensive), you'll get exactly what you need. Either product works, although I'm leaning toward the one in the first link. Good luck!

Quick update:

Good news (for now), I found a local granular gypsum fertilizer under the brand Gypblend (imported from Thailand). I'll look forward on when I can purchase one - but first, I got to find it.

https://shopee.co.id/product/171540730/12219562363

[Steve Johnson]

Excellent! I looked at the back of the bag, and (contrary to what I thought), it said that Gypblend has a pH of 7-7.5. Such being the case, you'll need to acidify your tap water at least for your alkaline mix. How much is something I still need to determine, so I'll work on that over the weekend.

[Steve Johnson]

Question for you, Adi...

I believe your Pak Tani 16-16-16 contains 5% Ca and 1% Mg -- is that correct? If so, is it reported as CaO and MgO? Just like the oxygen in P2O5 and K2O, the oxygen in CaO and MgO has no nutrient value, so we simply need to know the elemental percentages of Ca and Mg. If the Ca and Mg reported on the Pak Tani's label has a different chemical formula, let me know what it is.

[Wiandry Adi]

Excellent! I looked at the back of the bag, and (contrary to what I thought), it said that Gypblend has a pH of 7-7.5. Such being the case, you'll need to acidify your tap water at least for your alkaline mix. How much is something I still need to determine, so I'll work on that over the weekend.

I found Gypblend's official distributor's website and found the fert's certificate of analysis: http://www.agrotama.com/halaman/form/COA-Gypblend.html

Question for you, Adi...

I believe your Pak Tani 16-16-16 contains 5% Ca and 1% Mg -- is that correct? If so, is it reported as CaO and MgO? Just like the oxygen in P2O5 and K2O, the oxygen in CaO and MgO has no nutrient value, so we simply need to know the elemental percentages of Ca and Mg. If the Ca and Mg reported on the Pak Tani's label has a different chemical formula, let me know what it is.

Yes, it's 5% and 1%, respectively. Here's the complete formula according to the fert's official distributor for a better conclusion:

[Steve Johnson]

Very good! Since the Gypblend's guaranteed analysis shows a pH of 7.4, I think you'll need to acidify your tap water for the acid and alkaline mixes. How much still remains to be seen, so I'll work on it over the weekend. Also -- I'll send a PM to MikeInOz about thoughts on how much gypsum you should add to the mix. I may start doing it next year, and my proposal is to go with 90% mix and 10% gypsum in the pot. I'll ask him about that and see if he agrees or recommends a different percentage. The other question I'll ask -- is gypsum effective as a top dressing, or should we dig the granules down into the mix? When I get the answers, I'll pass them along to you.

Yes, it's 5% and 1%, respectively. Here's the complete formula according to the fert's official distributor for a better conclusion.

Would be kinda nice if I give you a comprehensive work-up on the ppm of all the nutrients in your watering solution:

• N, P, and K -- the primary major nutrients.

• Ca -- the secondary major nutrient.

• Mg and S -- the minor nutrients.

• So-called trace elements -- the micronutrients.

I already gave you the ppm numbers for N, P, and K, so I'll post the rest of them over the weekend.

[Wiandry Adi]

Welcome to the forum and thank you for taking the time to write such a lengthy introduction!
I see you already dived into the cultivation section of the forum regarding fertilizer. I was part of that conversation and learned a lot from it.
I look forward to seeiing photo's of your collection.

Hello, I've posted a new thread regarding on my collections. Details on the post: https://cactiguide.com/forum/viewtopic. ... 35#p403535

I hope you enjoy, and thanks for waiting!

[Steve Johnson]

Hello, I've posted a new thread regarding on my collections. Details on the post: https://cactiguide.com/forum/viewtopic. ... 35#p403535

I hope you enjoy, and thanks for waiting!

Excellent idea! I just saw your photos, and your plants are wonderful. It'll be a pleasure to see more of them, so please keep that thread going!

In the meantime, I sent a PM to Mike with questions on the following:

• How much gypsum you should add to your pots. I told him that your tap water before adding fertilizers has a pH of about 7.1, so your cacti may not be getting much in the way of Ca and Mg from there. If he concurs, this will factor into the amount of gypsum he and I recommend.

• Top dressing, or should you dig the gypsum granules down into the mix? If the answer is top dressing, it'll make the application of your gypsum a lot easier.

• What to do about magnesium? The fert "recipe" I recommended for you contributes only 4 ppm Ca, 4 ppm Mg, and 7 ppm S in your watering solution. What I have in mind is balancing the Ca in gypsum with the right amount of Mg by adding Epsom salt (MgSO4·7H2O) to your watering solution. The dilution I came up with is purely guesswork on my part. After Mike goes through all the details, he should be able to give you the right dilution.

The gypsum you'll buy has a guaranteed analysis showing a pH of 7.4, so I don't want to make any recommendations on acidifying your tap water until I know if the amount you'll add to your pots is enough to raise the pH of your acid and alkaline mixes. That's one of the questions I'm raising with Mike -- once he responds to my PM with all the answers, we can continue with the next phase of your action plan.

[Wiandry Adi]

Hello, I've posted a new thread regarding on my collections. Details on the post: https://cactiguide.com/forum/viewtopic. ... 35#p403535

I hope you enjoy, and thanks for waiting!

Excellent idea! I just saw your photos, and your plants are wonderful. It'll be a pleasure to see more of them, so please keep that thread going!

Thanks a lot, Steve! I appreciate your kind words. Due to the numbers of my collections, I can't cover them all in just a thread, so I'm planning a monthly update since lots of things happened in a month. I also kindly wait for your collection's update too. Can't wait to see those lovely blooms again!

In the meantime, I sent a PM to Mike with questions on the following:

• How much gypsum you should add to your pots. I told him that your tap water before adding fertilizers has a pH of about 7.1, so your cacti may not be getting much in the way of Ca and Mg from there. If he concurs, this will factor into the amount of gypsum he and I recommend.

• Top dressing, or should you dig the gypsum granules down into the mix? If the answer is top dressing, it'll make the application of your gypsum a lot easier.

• What to do about magnesium? The fert "recipe" I recommended for you contributes only 4 ppm Ca, 4 ppm Mg, and 7 ppm S in your watering solution. What I have in mind is balancing the Ca in gypsum with the right amount of Mg by adding Epsom salt (MgSO4·7H2O) to your watering solution. The dilution I came up with is purely guesswork on my part. After Mike goes through all the details, he should be able to give you the right dilution.

The gypsum you'll buy has a guaranteed analysis showing a pH of 7.4, so I don't want to make any recommendations on acidifying your tap water until I know if the amount you'll add to your pots is enough to raise the pH of your acid and alkaline mixes. That's one of the questions I'm raising with Mike -- once he responds to my PM with all the answers, we can continue with the next phase of your action plan.

I'll wait for what surprises Mike may come up with

[Steve Johnson]

Thanks a lot, Steve! I appreciate your kind words. Due to the numbers of my collections, I can't cover them all in just a thread, so I'm planning a monthly update since lots of things happened in a month. I also kindly wait for your collection's update too. Can't wait to see those lovely blooms again!

I finished my big photo shoot last weekend, so I have brand-new photos of each cactus in the collection. Good thing it's only 68 plants, otherwise I wouldn't be able to keep up on photographing them individually as I do for my end-of-summer reviews. I hope to get the 2023 party started in a few weeks. In the meantime, I'll keep my eyes out for your monthly updates.

I'll wait for what surprises Mike may come up with

Mike did respond to my PM, but I'm asking him a couple of follow-up questions. Here's what I have so far:

• He said that gypsum granules can be applied as a top dressing, so that makes things easy for you -- it'll be easy for me too since I have decided on adding gypsum granules to my pots next spring.

• He also said that there's no reason to be concerned about gypsum changing the pH as long as the water is pure or acidified.

You'll need to fertilize pretty much every time you water regardless of whether it's rainwater or tap water. But is your rainwater pure? If the rain hasn't been cloud-seeded, yes. However, if it has been cloud-seeded, then as far as your plants are concerned, the rainwater isn't pure. If your local authorities give you advance notice of cloud-seeding, you'll know that you need to stick with tap water.

I still need to figure out what you should do on acidification. Stay tuned for further details.

[Wiandry Adi]

I just found this information about phosphorus-solubilizing bacteria which are applied to soil to help plants acquire phosphorus and thus helping the issues caused by too many phosphorus. This sounds promising, so I was thinking if I could apply these bacteria to my collection. Not too much, perhaps about just a quarter teaspoon per plant once a month, and if there's desirable progress, I'll raise the dosage gradually.

Any thoughts on this? Like, will it work in gritty mixes I use?

References:
https://www.sciencedirect.com/topics/ag ... g-bacteria
https://www.mdpi.com/2077-0472/13/2/462
https://www.researchgate.net/publicatio ... mechanisms

[Steve Johnson]

I just found this information about phosphorus-solubilizing bacteria which are applied to soil to help plants acquire phosphorus and thus helping the issues caused by too many phosphorus. This sounds promising, so I was thinking if I could apply these bacteria to my collection. Not too much, perhaps about just a quarter teaspoon per plant once a month, and if there's desirable progress, I'll raise the dosage gradually.

Any thoughts on this? Like, will it work in gritty mixes I use?

References:
https://www.sciencedirect.com/topics/ag ... g-bacteria
https://www.mdpi.com/2077-0472/13/2/462
https://www.researchgate.net/publicatio ... mechanisms

Haven't heard of that before, so it's something you'd have to experiment with. IMO better if you lower the P by adding ammonium sulfate and potassium sulfate to your watering solution. Go back here and review what I showed you:

viewtopic.php?p=403467#p403467

What I propose is increasing the N from 51 to 65 ppm (ammonium sulfate increases the ammonium N) and increasing the K from 68 ppm to 97 ppm with potassium sulfate. 20 ppm P stays the same, so you'll have an NPK ratio of 1-0.31-1.49. I'll have to run some calculations and figure out the dilutions that'll get you closest to the target numbers, being mindful of the fact that you're using measuring spoons. If I come up with the right amounts for you, you won't need to experiment with something which may or may not work. I'll get back to you on this over the weekend if not before. By the way, 65 ppm N per feeding is certainly not excessive!

[Wiandry Adi]

In that case, I do know two ammonium sulfate and potassium sulfate ferts that I can get (and I see they're in water-soluble crystalline powder form). Shall I get those and measure their weights?

[Steve Johnson]

In that case, I do know two ammonium sulfate and potassium sulfate ferts that I can get (and I see they're in water-soluble crystalline powder form). Shall I get those and measure their weights?

Actually no, we have a handy-dandy calculator for that:

https://www.aqua-calc.com/calculate/vol ... nk-sulfate

https://www.aqua-calc.com/calculate/vol ... nk-sulfate

1 metric tsp. (5 cc) -- ammonium sulfate = 8.85 grams (1.88 grams N, 2.12 grams S), potassium sulfate = 13.3 grams (5.97 grams K, 2.45 grams S).

When you said "ferts", I'd just like to make sure they're pure ammonium sulfate and potassium sulfate, no other nutrients added. If they are, here are the dilutions:

• 1/4 metric teaspoon ammonium sulfate per 50 liters of water. This adds 9 ppm N to the 51 ppm provided by your other fertilizers.

• 1/4 metric teaspoon potassium sulfate per 50 liters of water. This adds 30 ppm K to the 68 ppm provided by your other ferts.

Grand total in your watering solution -- 60 ppm N, 20 ppm P, and 98 ppm K. 20/60 = 0.33 P, that's within the optimal range of 0.25-0.35. 98/60 = 1.63 K, also within the optimal range of 1.1-1.7. Because sulfur is an important minor nutrient, we'll look at that too -- 11 ppm S from ammonium sulfate, 12 ppm S from Potassium sulfate. Your other ferts contribute 7 ppm S, so the grand total of S in 50 liters of your watering solution is 30 ppm. I give my cacti 33 ppm S per feeding -- no need to be worried about sulfur toxicity. What I have in mind for your here is as close to ideal as one could hope for.

I'd like you to run another pH test, but with a new wrinkle this time:

• Fill one of your 50 liter buckets with tap water, test the pH, and write down the number.

• Dilute all of your fertilizers including the ammonium sulfate and potassium sulfate. Let the watering solution sit for about 10 minutes, then give it a thorough stirring. Test the pH of the watering solution and write down the number.

• The new wrinkle -- fill a clean glass jar with your watering solution, put a lid on it and let it sit for 7 days. Test the pH, then write down the number.

This tests the pH rebound effect, and you'll need more than 1 day to get an accurate result. If the pH of your test water is at or below 7.0 after 7 days, you'll know that the acidification provided by your ferts completely neutralizes the bicarbonate alkalinity in your tap water. Please let me know about the results of the test.

I still need to discuss gypsum with you, although I'll have to save that for the weekend. In the meantime, It would be helpful to know how much Ca and Mg you have in your tap water. MikeInOz came up with a good idea -- contact your local hydroponic grower or supplier for more information. They should be able to tell you about the Ca and Mg levels in the tap water. If they can give you the ppm numbers, so much the better. Once I know what the numbers are, we can figure out if you need to do anything beyond adding gypsum to your pots.

[Wiandry Adi]

Actually no, we have a handy-dandy calculator for that:

https://www.aqua-calc.com/calculate/vol ... nk-sulfate

https://www.aqua-calc.com/calculate/vol ... nk-sulfate

1 metric tsp. (5 cc) -- ammonium sulfate = 8.85 grams (1.88 grams N, 2.12 grams S), potassium sulfate = 13.3 grams (5.97 grams K, 2.45 grams S).

When you said "ferts", I'd just like to make sure they're pure ammonium sulfate and potassium sulfate, no other nutrients added. If they are, here are the dilutions:

• 1/4 metric teaspoon ammonium sulfate per 50 liters of water. This adds 9 ppm N to the 51 ppm provided by your other fertilizers.

• 1/4 metric teaspoon potassium sulfate per 50 liters of water. This adds 30 ppm K to the 68 ppm provided by your other ferts.

Grand total in your watering solution -- 60 ppm N, 20 ppm P, and 98 ppm K. 20/60 = 0.33 P, that's within the optimal range of 0.25-0.35. 98/60 = 1.63 K, also within the optimal range of 1.1-1.7. Because sulfur is an important minor nutrient, we'll look at that too -- 11 ppm S from ammonium sulfate, 12 ppm S from Potassium sulfate. Your other ferts contribute 7 ppm S, so the grand total of S in 50 liters of your watering solution is 30 ppm. I give my cacti 33 ppm S per feeding -- no need to be worried about sulfur toxicity. What I have in mind for your here is as close to ideal as one could hope for.

I'd like you to run another pH test, but with a new wrinkle this time:

• Fill one of your 50 liter buckets with tap water, test the pH, and write down the number.

• Dilute all of your fertilizers including the ammonium sulfate and potassium sulfate. Let the watering solution sit for about 10 minutes, then give it a thorough stirring. Test the pH of the watering solution and write down the number.

• The new wrinkle -- fill a clean glass jar with your watering solution, put a lid on it and let it sit for 7 days. Test the pH, then write down the number.

This tests the pH rebound effect, and you'll need more than 1 day to get an accurate result. If the pH of your test water is at or below 7.0 after 7 days, you'll know that the acidification provided by your ferts completely neutralizes the bicarbonate alkalinity in your tap water. Please let me know about the results of the test.

I still need to discuss gypsum with you, although I'll have to save that for the weekend. In the meantime, It would be helpful to know how much Ca and Mg you have in your tap water. MikeInOz came up with a good idea -- contact your local hydroponic grower or supplier for more information. They should be able to tell you about the Ca and Mg levels in the tap water. If they can give you the ppm numbers, so much the better. Once I know what the numbers are, we can figure out if you need to do anything beyond adding gypsum to your pots.

Alright, I'll get those ferts first. I'll check if I have time this weekend or next weekend to do this entire project. Here are my candidates:

https://saprotan-utama.com/wp-content/u ... us2020.pdf
https://meroketetapjaya.com/files/uploa ... keSOP@.pdf

Let me know if there's any change in dilution of these ferts according the percentages of elements provided by the ferts' distributors.

Also regarding water hardness, I'll get the test kit some time later (hopefully within this month) or going to Flona again to get info about this. In the meantime, I'll try to get any information regarding water hardness result in other region for a reference (regions within Java).