North American Fruit Explorers mailing list at ibiblio

["Jim Fruth" <jimfruth@charter.net>]

Alan Haigh wrote, "As I've stated on this site before, I have seen very 
healthy and productive blueberries growing in soils with a pH in the mid 6's 
and others corroborated this observation."


Alan,
   I seen to remember that mentioned where growers have bound up the soil 
calcium and added additional magnesium but I don't recall anyone saying what 
they did to de-activate the calcium.  If I had a corner of land that I 
didn't care what happened to, I'd try that.  If you were to apply enough 
phosphoric acid (phosphoric acid is a liquid) to bind the calcium turning it 
into the insoluble form, calcium phosphate, you should be able to acidify 
the soil alot faster than by acidifying with sulfur.  The soil buffers would 
likely be neutralized in the process.
   I don't know if that has been tried or, I should say that I haven't 
found anything like that in the literature.  It was probably accomplished 
but not written about because phosphoric acid is relatively (potentially) 
dangerous to handle.  It should work if you knew how much soluble calcium 
the soil contained and applied only as much phosphoric acid as needed 
because it would be very easy to apply too much acid lowering the pH too 
far.
   The phosphoric acid would make the calcium unavailable to plants but 
only momentarily.  That is because soil bacteria can reduce calcium 
phosphate making minute amounts of calcium available to the blueberries and 
blueberries do need some calcium.

Jim Fruth
Brambleberry Farm
Pequot Lakes, MN  56472
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