Alan Haigh asked, "Does gypsum supply any magnesium as does dolomitic lime?"
Not likely or, at best, in trace amounts.
Alan, you have my curiosity..........................if your "sodic"
soil is low in sodium, what other cation is present that causes the
condition?
If you are ever tempted to use Greenstone, be warned that any amount
more than a tiny bit may cause manganese toxicity.
Jim Fruth
Brambleberry Farm
Pequot Lakes, MN 56472
For jams, jellies & syrups:
www.bberryfarm.com
(877)265-6856 [Store]
(218)831-7018 [My Cell]