Mm, don't think that would cut it. The high pH water actually prevents the plant's uptake of other nutrients. Magnesium certainly absorbs through the leaves, (I use it a lot on my orchids as an additive to my foliar feed) but it wouldn't help the plant take up the other nutrients it needs from the soil.

Twelve teaspoons of Epsom salts finally reduced the pH of half a gallon of well water by one point. Not going to be able to do that too often, I guess.

I'm just tossing out a random idea, perhaps a terrible idea. Some people suggest using vinegar as a spot-weed-killer.

But could you use it to neutralize some of the alkalinity?

Vinegar certainly is an acid - acetic acid.

https://www.amazon.com/dp/B008GTGE7U/

https://www.amazon.com/dp/B0052E9BH2/

20% Horticultural Vinegar, 4 gallons for $52 or single gallons for $16.

Household vinegar is 5%, so ag vinegar is 4X as strong.

I guess if you use it only to neutralize the well water, you can't kill any plants with it. I wonder how much you would need to neutralize 10 square yards of pH 8.5 soil? My guess would be "LOTS".

At least it will be broken down to CO2 and nothing else by soil organisms. It's pure organic "brown" in composting terms.

>> Twelve teaspoons of Epsom salts

Hmm, that's two ounces if they were level teaspoons. It wouldn't surprise me if two ounces of household vinegar neutralized a half gallon of well water. You might have to use an eyedropper with the agricultural-strength vinegar.

But as Dave says, that depends on "total alkalinity", like the concentration and buffering power of your minerals.

When I was a kid, I used to think: "why not use dilute nitric acid? That would even add nitrogen!" Having worked since then in a chemical plant with concentrated nitric acid, I don't even want to THINK about it.

Plus, today, the potential for using nitric acid to make explosives would probably "get us on a list" for just thinking it.

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

>> your sand is carbonate,

OUCH! Don't try to neutralize that all the way! It will dissolve into CO2 and float away.

dyzzypyxxy said:Twelve teaspoons of Epsom salts finally reduced the pH of half a gallon of well water by one point. Not going to be able to do that too often, I guess.

Using that much Magnesium sulfate, you're bound to get magnesium toxicity symptoms on plants as well.