Salt deposits

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ElieEstephane
Posts: 2909
Joined: Tue Dec 13, 2016 12:10 am
Location: Lebanon (zone 11a)

Salt deposits

Post by ElieEstephane »

Interestingly enough, my soil is acting as a calcium adsorbant. My potting mix is mostly grit. The english name of the mineral is on the tip of my tongue. It's high in iron and sometimes i find solid iron pieces in it. It's purple/brown and we used to add it in the raw materials for portland cement production. I will remember the name!
Anyway, this grit is abundant in certain areas of the montains of Lebanon. You can find huges rocks of this mineral and the grit is eroded from it and sitting at the bottom of rock. I used to collect from 2 locactions that are only separated by less than a kilometer: locaction one is more eroded but solid 2-4mm particles and locaction 2 is less eroded but more fissile 4-5mm. The problem with salt deposits is occuring only with site 2 grit and it seems nad as you can see in the pictures.
This potting mix is definitely gonna be discarded and im going back to site 1.

I your opinion, after removing the old mix, what would be the best solution to clean the roots? Maybe a soak for say 10 minutes in a slightly acidic (ph 5.5-6) should be enough or you you would treat it differently? Fortunately most of my plants have site 1 grit.

Looking at the silver lining in all of this, since site 2 grit is apparently more porous and able to physically/chemically bind calcium, i may be able to fashion some sort of rudimentary water filtration system to water my plants. If only i can remember the name of the mineral to look at the situation chemically to see if it's ion exchange or physical adsorption ](*,)
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Last edited by ElieEstephane on Thu Dec 07, 2017 12:05 am, edited 1 time in total.
There are more cacti in heaven and earth, Horatio, than are dreamt of in your philosophy.
One of the few cactus lovers in Lebanon (zone 11a) :mrgreen:
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TimN
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Joined: Mon Aug 06, 2007 9:01 pm
Location: Phoenix, Arizona USA

Re: Salt deposits

Post by TimN »

Let me as a question: is the water you use on your plants untreated? Is your tap water hard? (Water in Phoenix is around 400ppm) Is your tap water alkaline? I think this looks more like calcium which has to do with the content of your water and it's alkalinity than your media.

If your water is alkaline you should acidulate it to ph 4.5-5.5. (water in Phoenix is ph 7.5 - 8.5) First, the plant is expecting acidic water (rain is acidic everywhere to some degree, when I've measured it in Phoenix it was about ph 5.0) and second it can help dissolve any accumulated mineral deposits. I have similar mineral deposits on the bottom of my pots, but less so on the top dressing. This necessitates watering heavily, so it can dissolve and flush the minerals.

As far as alkaline soil is concerned, most (not all) cactus grow in alkaline soil, so alkalinity in the soil isn't a big issue unless it's extreme or the plant is expecting something different (like the cactus in the picture). It appears as though the plant in the pictures is an epiphyte which is probably expecting something more acid, soil-wise. - I may be completely wrong, I don't raise any jungle cactus.

As far as washing the roots is concerned, I wouldn't, but it probably won't hurt. You can soak the whole plant, pot and all in a slightly acidic solution and avoid disturbing the plant. If you mix has pearlite or pumice it might float away, but otherwise you're good.

I think the important concept is that not all cactus grow in the same conditions (ph of soil, ph of water/rain, richness of soil, watering/rainfall volume, etc, etc. Finding out what the plant prefers in at least the general sense is helpful in keeping them alive.
Disclaimer: I'm in sunny Arizona, so any advice I give may not apply in your circumstances.

Tim
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ElieEstephane
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Joined: Tue Dec 13, 2016 12:10 am
Location: Lebanon (zone 11a)

Re: Salt deposits

Post by ElieEstephane »

First of all thanks for the detailed answer Tim. Much aappreciated.
Point 1: yes it's untreated tap water. it's definitely calcium deposits since our tap water ia very hard and i barely fertilize. Our natural georgraphical structure is almost purely very chalky limestone. As to the relation with the growing medium, i'll get to that in a bit.

Point 2: Most of my waterings are acidified to around ph 6 using acetic acid, sometimes from white vinegar and sometimes from apple cider vinegar. Don't you think 4.5-5.5 is a bit too acidic? I never knew rain was acidic. I suppose it's true with all the pollution. As for salt deposits, they only occured on pots with grit from site 2. All other pots are squeaky clean.

Point 3: affected plants range from desert cacti to epiphytes to some succulents including haworthias which i believe like alkaline soil-not sure.

Point 4: im gonna be repotting anyway next spring so i might as well insure the roots are healthy and clean. I usually do a water soak for all my plants before repotting. Ita helps transition through the shock.

Point 5: im very fussy about my cacti since while having 100s of cacti, i care about each one individually. Every species has a tweaked version of my potting mix to keep it happy. They are spreak all over balconies and in the garden and around the house to ensure every plant gets the correct amount of sunlight and humidty. Some even move with me to my summer house to benefit from cooler temperatures.

Finally, i don't mind salt deposits but if i can avoid them then why not. The only reason that i found this topic interesting is how the same mineral acts differently from 2 locations. Location 1 has no deposits at all while locaction 2 has a terrible state of salt deposits. I am kind of convinced it has to do mostly with the mineral in my mix since this is what my experimental proof suggests or i would have had deposits on all my pots. Plus the more rock i have in my mix, the more deposits i have. I will run a few tests at work on the rocks including XRD and nitrohen/BET porosimetry and surface structure but the lab is swamped now. Once i have these results, i can know for sure why this is happening.
There are more cacti in heaven and earth, Horatio, than are dreamt of in your philosophy.
One of the few cactus lovers in Lebanon (zone 11a) :mrgreen:
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ElieEstephane
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Joined: Tue Dec 13, 2016 12:10 am
Location: Lebanon (zone 11a)

Re: Salt deposits

Post by ElieEstephane »

The mineral is some sort of Hematite which has a good content of iron oxide and it's use as an addative to raw materials for portland cement manufacture.
There are more cacti in heaven and earth, Horatio, than are dreamt of in your philosophy.
One of the few cactus lovers in Lebanon (zone 11a) :mrgreen:
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stefan m.
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Joined: Mon Dec 04, 2017 5:28 pm
Location: Skopje MK

Re: Salt deposits

Post by stefan m. »

Ive noticed what i would like to label as "soil alkalization". Basically over time, the soils changes color , probably due to nutrient depletion and calcite buildup. The color of the soil tends to change from dark brown/black to grey/greyish yellow.
Of course, repot or cactus likely dies-ive seen these really old trays with sanseverias in them, and they croaked by the end of my second year. Their soil was solidified like concrete. In fact the same happened to my red pilosocereus a week ago and had to repot it as well.
DaveW
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Location: Nottingham, England/UK

Re: Salt deposits

Post by DaveW »

Have you tried leaching them? Make sure the water flows freely out of the drainage holes in the base of the pot to waste and is not reabsorbed. This can be a problem with plants grown in the house standing on saucers where the draining water is reabsorbed. In the greenhouse or outdoors you can water to excess so it always flows freely out of the pots drainage holes to waste to mitigate salts build up without worrying about the damage that would cause in the house.

https://extension.umd.edu/hgic/watering ... ouseplants

https://www.gardeningknowhow.com/housep ... plants.htm

Whilst some cacti grow in alkaline soils there has long been a debate as to whether they need them, or simply grow there because they can tolerate them where other more faster growing competing plants cannot. A Brazilian botanist suggested that cacti inhabiting alkaline soils only grow when they receive acid rainwater and when the underlying strata turns the water alkaline stop growing again until the next rainfall.

Certainly it seems N. American plants are more tolerant of slightly alkaline soils than many of the S. American ones, but as with all "rules" they are not universal.
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ElieEstephane
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Joined: Tue Dec 13, 2016 12:10 am
Location: Lebanon (zone 11a)

Re: Salt deposits

Post by ElieEstephane »

DaveW wrote:Have you tried leaching them?
Yes i have tried flushing them with acid water but as soon as the pot dries the salts reappear. That's why i deduced it had to with my rocks since salt deposition is only occuring on pots with this mineral.
Thanks dave.
There are more cacti in heaven and earth, Horatio, than are dreamt of in your philosophy.
One of the few cactus lovers in Lebanon (zone 11a) :mrgreen:
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