[jason g]

hi there ,hope someone can help me out again.

i have a bag of hydrated lime left over from dashing my bungalow,the qeustion is can i use this on the allotment or would it be best to get a bag of lime from the local agricultural shop??

[tode]

No problem if its just lime. Some of the bags are lime/cement mix, which should be marked on bag.

[peterjf]

Be carefull the builders lime doesnt end up being too strong, it can burn the hell out of your plants,

go to your local allotment site to buy the right stuff

[tode]

Pete, hydrated builders lime and agricultural lime are the same thing (slaked lime). What really burns is quicklime, which is quite dagerous, but can also be used if you're careful.

I always have a bag or two of quicklime for my grass cuttings: stops them turning acidic and becoming a slimey mess.

[Babstreefern]

I've just started putting lime on my beds as its pretty acidy(?) and will let it over winter.  But yes, lime and hydrated lime are one the same.

[jason g]

thanks for your help

[DD.]

I've just started putting lime on my beds as its pretty acidy(?) and will let it over winter.  But yes, lime and hydrated lime are one the same.

No no no.

Lime is alkaline!!!

[tode]

DD, I think Babs means that her soil is acid.   

[Salmo]

Hydrated lime and agricultural lime are not the same thing.

 Agricultural lime is ground limestone and it should be used in routine liming. It is slow acting and easy to handle.

Quicklime is limestone that has been heated to red heat. I would think that it is not for sale as it is quite nasty in that state. If water is added to it, or it is just left out in the air, it reacts and produces a lot of heat. What results is hydrated lime which is a very fine powder.

Hydrated lime can be used on the soil the same as agricultural lime. Because it is a fine powder it is quick acting and is often used even when crops are growing if there is an acidity problem that needs correcting. Also because it is a fine powder great care must be taken as it easily blows about and is painfull if it gets into eyes.

Builders lime is hydrated lime. Sometimes it has gypsum added, which will do no harm to the soil, and sometimes there are other additives that make it work more easily when building. It should say on the bag.

[DD.]

DD, I think Babs means that her soil is acid.   

That's not the way it reads. If that was the case the quote would be:

I've just started putting lime on my beds as they are pretty acidy(?)

rather than:

I've just started putting lime on my beds as its pretty acidy(?)

[tode]

Sorry DD if I was a bit too quick off the mark 
I just assumed that everyone knew that lime is not acidic.  Are you out there Babs?

[tode]

Hi Salmo,
Sorry to be contradict you, but many people get a bit confused about lime and what it is.
The natural base mineral for lime is calcite, CaCo3, found very pure in limestones and, less pure, in chalks. Both of these can contain a proportion of magnesium (magnesian limestones).
Limestone is not lime, but is used for making lime. It is sometimes used in agriculture because of its lower cost, but it's less effective and slower acting.

All lime is made by heating to produce quicklime (calcium oxide) which, as you say, is very reactive. It is sold both for agricultural and construction use. (As well as for lawn mowings XX ). Eye, skin and breathing protection needed during use. Because of health risk it can be obtained in granular form which contains less dust.
"Standard" lime is made by adding quicklime to water, which gives off a lot of heat during the reaction, and gives hydrated lime Ca(OH)2, which is the product most often used in building work.
If you buy builder's lime it will have no additives, excet, as I said, the lime/cement mixes sold for DIY, but which are labelled.

As far as I know, gypsum is never added, but plaster (made from heated gypsum) is added to lime for specialist restoration work, although this use is now discouraged. I don't think you'll find these in DIY outlets, though.

A couple of interesting links:
http://www.ima-eu.org/fileadmin/downloads/minerals/Lime-fact-sheet.pdf
http://www.britishlime.org/lime_con01.php


Out of interest, gypsum (and plaster) isn't good on clay soils as it deflocculates clay, making it very sticky, whereas lime flocculates clay, making it easier to work.

Sorry if this was a bit long, 
Tony

[Salmo]

tode - very informative.

The lime for sale in garden centres is very confusing. I have seen both hydrated lime and crushed limestone under the ticket of garden lime - whatever that is.

Agricultural lime, as used by farmers and seen in heaps waiting to be spread on fields, is usually crushed limestone. Sometimes this is dolomite limestone if magnesiun is needed. In the Eastern counties they also use waste lime from the Sugar factories after it has beed used in the sugar refining process to precipitate impurities. That is hydrated lime but also has other things such as phosphorus in small quantities.

Contrary to what you say, gypsum is a very good clay flocculant. It is used where the soil is sad but the pH is already high. An example of this is where soil has been flooded with saltwater and needs restoring. The Dutch use it widely when reclaining the polders.

[tode]

Salmo, I have no experience of land that been flooded by salt-water, just know that it "poisons" the land, but no idea why.

We used to transport the waste lime from our local sugar factory -- it was in great demand by all the farmers (in great part because they only had the transport to pay  ).
Can't remember the details now, but something like 8000 cubic yards per year 
All went in a few weeks, though !
Was used for filtering the extracted sugar solution.
Tony