Rick, howdy! Thanks for throwing in the science while I was busy in the lab today (and can I say I love that you thanked the sulfur oxidizers... a man after my own heart).
Yes, it's the acidity (low pH) of the vinegar that makes it kill weeds, so putting it into a solution where it's neutralized will take away that property.
I wasn't sure of the scale of Elaine's garden/farm when I first posted. What works on my tiny lot (pine straw and rainwater - we have 300 gallons capacity for 1/8 acre total property, no more than 1/4 of which is in production at any time) doesn't make as much sense in a larger-scale setting. The Take Down and agricultural vinegar you mentioned both seem like decent options for acidifying the water rather than the soil.
It confused for me a minute when you (Elaine) mentioned sand being alkaline - your sand is carbonate, from ancient corals and other creatures in the water. I'm also on nearly pure sand, but it's silica (glass), which is in itself neutral. We have very little organic matter, and what we have is from the pines, so it's slightly acidic, and very nutrient-poor. We share the problem caused by sand's texture, though - the soil doesn't hold water at all, so even if it rains heavily one afternoon, the plants are all wilted by the time the sun is high the next day. But to be fair, I'll take the extra watering over all the trials and tribulations I hear from people who garden in clay
