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Old 04-02-2011, 06:15 PM
aaronleadley aaronleadley is offline
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First recorded activity by GardenBanter: Feb 2011
Posts: 2
Post Liming with calcium oxide (quicklime)

I have been a lurker on these forums for a while now and many others, this is my first thread .

With regards to liming many people use slaked lime (Calcium carbonate) however when anyone seems to ask the question can I use quicklime everyone gets rather iffy and nervous around the substance.
I come from a family of traditional building restoration stonemasons so we make a lot of lime mortar and render.

The problem many people have with using quicklime is the fact that it is a caustic substance that when it comes into contact with water it produces a highly exothermic reaction (gets hot)
However quicklime is not as bad as people would have you believe, yes it can sting if you breathe in loads but the issues of it's use are much overplayed amongst gardeners.

The key with using quicklime is not to slake it in a bucket and then apply this lime gum to the land.- may seem simple but people actually do this.
what I do is I fill a bucket with it and get my trowel and throw it around the soil and rake it in.
After this I give it a quick soak with a watering can.
However the reaction in the soil is very slow and relatively harmless because of the length of time it takes to react and the fact that it is underground.
After you apply the lime in autumn and rake you wait for the winter frosts and rains to do their work, by mid february the calcium oxide is now calcium carbonate (garden lime) what should be done now is forking the lime in.

It is not the problem of quicklime and it being a dangerous substance, it is the problem of lack of understanding and stupid fears that if you are careful you can avoid.

for those who do not understand how garden lime and quicklime differ here is a quick version of the lime cycle.

Limestone (Calcium carbonate) CaCO3
apply a great heat and the carbon and 2 oxygen become CO2 and float off.
Quicklime (Calcium oxide) CaO
Add water and mix about this becomes slaked lime which the reacts with the carbon dioxide in the air. when the CO2 is added back to the CaO it becomes CaCO3 and thus is Limestone again or to you and I, Garden Lime.

I hope this has helped and informed you in the use of liming with quicklime.