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For a soil to have a pH of 7.6 while being very low in the major cations is odd.  Which method of measuring pH did you use?  (Those pH wands aren't very reliable.  I normally use a Helige-Truog kit, or "pHydrion" papers.)  A "sodic" soil would test very high in exchangeable sodium; and in any case, these are usually found in arid areas (although there are a few in Louisiana).

What is the geographic setting of this soil?  Is it in an area that is reclaimed from tidal marsh?  Sometimes such soils will have high pH in situ, but after drying, will exhibit pH values down around 2.8.

I'm in my office today until about 2:30 or so...if you'd like to discuss this in detail, send me a private e-mail to eddie.earles@md.usda.gov, and I'll send you my phone number.

Eddie Earles

 

-----Original Message-----
From: Alan Haigh
Sent: Jan 2, 2009 10:55 AM
To: nafex@lists.ibiblio.org
Subject: [NAFEX] agronomy question

I am in the Northeast and in the many years I have dealt with hundreds of sites and soils I have always been able to deal with pH issues with either the addition of lime or sulfur.  I only rarely run into base soils and when I have it is always the result of a lot of native limestone in the soil.

 

I have been hired as a troubleshooter recently at 2 sites where testing reveals soils that are very low in calcium, magnesium and manganese andsodium, but high in most other tested minerals.  The pH at both sites is around 7.6.  Because measured sodium is low so I'm guessing the soils may be sodic.  The soils are medium course, without excess clay and have a good amount of organic matter.

 

On one of the sites they are trying to modify for blueberry and strawberry production on the other mixed vegetables (home orchards and veg gardens for tripple digit millionaires).  Any suggestions, especially amending proportions per 100 sq.ft?

 

Does gypsum supply any magnesium as does dolomitic lime?