Supersoil Booboo

[Wanderlust]

So I mixed up 15 cans of supersoil to subcools recipe and I just realized I added hydrated lime instead of dolomite lime :nailbiting:
I've never used hydrated lime before, but I've read it can burn your plants easily if you overdo it. Its also not a substitute for dolomite lime as a soil amendment. Anyone know if 3/4 - 1 cup of hydrated lime per 12 cubic feet of soil is going to be problematic? Should I still add dolomite to act as a pH buffer and magnesium supplement? My tapwater is borderline hard and I'm not sure if that would be too much calcium. I would hate to have to spend and make another batch...

 

[sensicloud]

I think as long as you didn't overdo the hydrated lime you don't have anything to worry about.

 

[Seamaiden]

I don't think that amount of hydrated lime will be a problem. I would still add some DL, something to help provide carbonates at least, which is a huge part of what DL offers you in terms of pH stability.

 

[soserthc1]

oyster shells are a buffer and i was just reading about lime this morning brb....

 

[Seamaiden]

Yes they are! Why? They're comprised primarily of CaCO3, aka calcium carbonate. :D

 

[soserthc1]

From TLO - Dry lime in your mix serves several purposes in TLO growing. First of all you should never add lime directly with dry nutrients , such as in spikes and layers - this is due to the instant reactions this causes with with other nutrients , which can be directly detrimental to your roots ....Hydrated lime should be avoided completely due to its extreme power in can easily kill life and take your ph into deadly ranges killing your plants......

Directly from the tlo book which should be about the same as subcool - again not my words and you can't always believe what you read as people have different opinions but that is what i got for you ....

good luck
SoSer

 

[Wanderlust]

I'm sure TLO is a knowledgeable source. I'm really curious how much hydrated lime is used under normal application. I know people water it in at 5ml per gallon to correct acidic soil conditions temporarily. There are old George Cervantes quotes (not the best source I know) saying to add half a cup to a full cup per cubic foot of soil. Another source cites using 2/3 the amount of dolomite lime. A member from a tomato forum added 2 cups hydrated lime to 4 cubic feet of soil and ran into necrotic spots on the leaves after a week. Reading these, then I might be able to get away with 2/3 cup of hydrated lime per 12 cubic feet of soil. Its a bit over 700$ to make another batch of supersoil, which I'd like to avoid unless I know the hydrated lime is going to be a problem.
I know hydrated lime has a pH upwards of 10. If I add dolomite, would that buffer the pH back down towards 7? 3/4 cups of dolomite per 12 cubic feet isn't much, but I feel like I might be further risking calcium toxicity.
Also, I use tap thats borderline hard. It would be cheaper to invest in RO than it would to make another batch of soil. Would using RO offset any burn caused by hydrated lime? I'm assuming the burn from hydrated lime is caused by either high pH or calcium toxicity...

 

[Wanderlust]

Well I just got off the phone with a reputable soil science guy and he said there shouldn't be a problem with that amount of hydrated lime. He said it will raise the soil pH a little bit, but adding about half a cup of epsom salts (already in the recipe) or some langbeinite should offset that.
Another tidbit of information I learned in that conversation is that he said not to buy epsom salts from a drug store, and to find an epsom salt meant specifically for gardening. Drug store epsom salts can sometimes be binded to other trace minerals, including heavy metals. Interesting.
:bag:

 

[Seamaiden]

Add more organic matter to the total soil volume, then add in some more DL. RO has no pH buffering capacity, while hard tap water likely does have quite a bit. I would combine RO with tap water. I just cannot imagine that a single cup of calcium hydroxide would taint an entire 12'cu of soil mix, to cause a toxicity? I could be wrong, but it seems insignificant to the total volume to me. That said, I don't work with hydrated lime, I work with gypsum, oyster shell flour occasionally, and DL occasionally. I prefer gypsum because it doesn't really keep pH shifted one way or the other, and I, too, have very hard water (well).

Re-reading your post, I'd add more peat. Hunnert percent, a couple more cubic feet of peat. It will counter the high pH of the calcium hydroxide.

 

[Seamaiden]

K, then... never mind, and good call on your part!

 

[oregonized]

the hydrated lime has a much higher CEC than dolomite. that's the key of why it can raise pH quickly, I think.

normally slaked lime is used to neutralize pH.