Gardeners refer to acid or alkaline soil. What they really mean is soil that is largely chalk based (alkaline) , like mine, or clay and humus based (acid). The practical difference is that you can't grow azaleas or hydrangeas on chalk or decent brassicas on clay. Theory has it that an alkaline soil "locks up" iron and magnesium necessary for chlorophyll production. I live on top of about 200-ft of solid chalk, so adding chelated iron has no effect.
It stands to reason that you can't measure the pH of a dry-ish soil with a conventional glass membrane electrode, hence the reason for a standardised soil analysis test.
Most of my work was with water and sewage, but I seem to remember that for some of the solids analyses, soil would first be dried at about 100 Celsius, then rehydrated to form a slurry.
The only things that appreciate a chalk soil are the sodding snails.