North American Fruit Explorers mailing list at ibiblio

["Donna &/or Kieran" <holycow@cookeville.com>]



Alan wrote:

 

"As far as the reliability of the tests that were sent to a laboratory, I double checked the pH of the soils and they tested at 7.2, which is as high as my kit goes. 

 

 The biggest question I have is how can a soil have a pH of 7.6 and be deficient in available calcium.  I'm guessing the calcium is tied up and if this is true will adding sulfur free it up somehow?  Or is something besides calcium driving up the pH, meaning I'll need sulfur and calcium sulfate?  I feel so ignorant at moments like these! "

 

 

Others seemed equally mystified.  Neil Kinsey explains all this in his book HANDS ON AGRONOMY.  Calsium drives up soil pH, but magnesium drives it even higher.  Magnesium buffers at 1.6X the rate calcium does.  (and it won't drop out of solution, unlike calcium, which explains why magnesium deficiency is almost always involved in kidney stones)   Jeff Poppen farms north of Carthage TN, source of the nearest limestone, with the small problem that it's dolomite.  He has seen Ca deficiency symptoms for years on his farm, and was puzzled that liming didn't help.  Adding Ca phosphate did, and that's how he figured it out.  With a 2:1 ratio of Ca to Mg, no amount of additional 2:1 lime was going to raise the ratio. 

    Blueberries don't care about pH per se, they only need to avoid calcium.  Get an A&L Labs test that will tell the Ca:Mg ratio.  If it's whacked out for normal crops, say 2:1 Ca:Mg (from dolomitic lime, check your soil map for that info) or "worse", blueberries will be happy.  If it's the ideal 6:1 or 7:1, you'll have to bring down the ph or as others have said, add a whole lot of organic matter.  The soil test would solve the mystery at once, but if you have time you can just look for some wild blueberries on the property, or do a small test planting.  If they don't turn yellow, you are in business.  Hector Black has a very profitable PYO blueberry planting on TN bottomland.  Our limestone here is high Ca lime, and he has to throw sulfur around every year to combat the nice moderate pH that we up on ridge land would practically kill for.     Donna

   

P.S.  Incidentally, if any of you would like to get your hands on some cheap farmland, you might find out where the nearest source of dolomitic lime is in your area, and look see if there is what looks like good farmland in the vicinity that has been abandoned.  Chances are the Ca:Mg ratio is too low and no one has been able to figure out why the land won't produce.  Neil Kinsey talks about the black much soils along the Missippi having chronic Ca def problems from this.