North American Fruit Explorers mailing list at ibiblio

[David.Maxwell@dal.ca]

I inadvertently responded to Helene's message directly to her, and not to the list, as I intended.  So here is my response (several days late), and request for info from wiser heads:

Most interesting that you should ask.  Dolomite is a form of limestone, the kind that occurs naturally here in Nova Scotia, (a province on the East coast of Canada).  If one goes to the Co-op to buy "lime" to raise the soil pH, this is what you get.  (And we normally have to lime our soil.)  The catch is that it is composed of a mixture of calcium carbonate and magnesium.  I myself have a problem in that my soil pH is still a bit below optimum for my apple trees (6.4), but the magnesium content is "excessive" (738 kg/ha.).  Adding more dolomitic lime to correct the pH would only exacerbate this.  What I have not been able to find out is just what, (if any), the actual "toxicity" of excess magnesium is.  Everything I have read talks vaguely of it being "bad", but I can't find anything specific in terms of just what it does, what the manifestations of toxicity are, or whether indeed it actually matters.  Any wise words from knowledgable NAFEXers?  (The folk at the co-op just look blank when I talk about "calcitic lime" vs dolomitic lime.)

On 25 Apr 2008 at 13:52, Hélène Dessureault wrote:

> 

> Good afternoon,

> 

> Does anyone use dolomite as a soil additive and if so,any special comment on the subject?

> 

> Hélène, zone 3-4. north of Ottawa