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Old 11-07-2004, 07:02 AM
David Hare-Scott
 
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Default Whats difference between pulverized and hydrated lime?


"pantuvarali" wrote in message
...
Lime is CaO (Calcium Oxide) and it is hygroscopic-i.e., water absorbing.
Unless one used lime right from a kiln, lime picks up around 1% H2O.
Now if you mix lime with water, you get calcium hydroxide Ca (OH)2. In

most
tropical countries, this hydrated lime is pained on walls. Yes- it kills
most bacteria.
All pulverized lime is hydrated unless you store in Nitrogen atmosphere.

The
lime that is used in gardens is just lime (pulverized or otherwise) which
has naturally picked up some moisture.



The lime that is used on gardens mostly ie "garden lime" is Calcium
Carbonate not Calcium Hydroxide. Hydrated or slaked lime or builders'
lime, Calcium Hydroxide, may be used on gardens in some cases but it must
be used differently. Both raise the pH (reduce acidity) but garden lime is
slower acting and is less likely to raise the pH an excessive degree if
applied heavily which can happen with hydrated lime. Both are used to amend
the soil by raising the pH (so making other minerals available to plants)
and/or to supply Calcium.

I cannot see how applying either lime to the soil could stop insects or
animals from eating the plants. Applying hydrated lime to cover the plant
as a dust might discourage those wanting to eat it but at the same time it
will wash off easily and then start amending the soil pH which may be quite
unwanted, especially if you are growing acid-loving plants. There are much
better ways to keep the bugs off your plants.

I suggest that you talk to the more experienced gardeners at your community
about what sort of lime they use, why and how much they use, before you do
anything rash.

David