pH shift /organic soil grow/time for lime??

[pcduck]

Hydrated lime is all calcium,

This is incorrect. Depends on the lime used.

There is also hydrated dolomitic lime.

Lime is a generic term, but by strict definition it embraces only the manufactured forms of lime—quicklime and hydrated lime. It does not include limestone, which is the feedstock for lime manufacturing.
Quicklime, the product of calcination of limestone, consists of the oxides of calcium and magnesium, and in the United States it is available in three forms:
High calcium quicklime--derived from limestone containing 0 to 5 percent magnesium carbonate.
Magnesian quicklime--derived from limestone containing 5 to 35 percent magnesium carbonate.
Dolomitic quicklime--derived from limestone containing 35 to 46 percent magnesium carbonate.
Hydrated lime is a dry powder manufactured by treating quicklime with sufficient water to satisfy its chemical affinity for water, thereby converting the oxides to hydroxides. Depending upon the type of quicklime used and the hydrating conditions employed, the amount of water in chemical combination varies, as follows:
High calcium hydrated lime--high calcium quicklime produces a hydrated lime containing generally 72 to 74 percent calcium oxide and 23 to 24 percent chemically combined water.
Dolomitic hydrated lime (normal)--under atmospheric hydrating conditions only the calcium oxide fraction of dolomitic quicklime hydrates, producing a hydrated lime of the following chemical composition: 46 to 48 percent calcium oxide, 33 to 34 percent magnesium oxide, and 15 to 17 percent chemically combined water.
Dolomitic hydrated lime (pressure)--this lime is produced from dolomitic quicklime under pressure, which results in hydrating all of the magnesium oxide as well as all of the calcium oxide, producing the following chemical composition: 40 to 42 percent calcium oxide, 29 to 30 percent magnesium oxide, and 25 to 27 percent chemically combined water.

 

[Hushpuppy]

PC: everything I have seen on "hydrated lime" and what is offered for sale is total calcium based, while "dolomitic lime" that I have seen is Magnesium based. I have never seen hydrated dolomitic lime but I guess technically you are correct. So I guess the key here is to look for Dolomitic lime, or should I direct them to you first so that you can give them the specifics?

 

[pcduck]

HP...Like nearly everything in this growing of mj, it is quite hard to give specifics. Some use lime and some don't. I feed the soil and reuse my soil, and use very little lime. While others use hand fulls. When I use hydrated dolomitic I use even less because of how fast it works.

IMO the use of lime is over used by many. If you mix your soil correctly a grower should not need hand fulls to maintain the pH. Plus all that calcium builds up in the soil and locks out other nutrients.

The 50# bag in the pic below is hydrated dolomitic lime. It will last me 2 lifetimes of growing in the amounts I use. With some left over.

View attachment IMG_20140721_184616_273.jpg

 

[shahomy]

The dolomitic lime has a small amount of calcium but mostly Magnesium.

Not trying to nit-pic, seriously I`m not....but my bag of Espoma "organic" garden lime says 21% calcium and 10% magnesium, anyway...