Epsom salts works best where there is a magnesium deficiency in the soil. If you don't have that, there's not really any reason to use it.
Mr Hunt does not live in the desert, so i would take his advice with a grain of salt. Ms Becky I share your sympathy as i am also dealing with alkalotic soils in New Mexico. To answer you question regarding pH; a chemist friend of mine tried lowering the pH of the soil with pure hydrochloric acid... did not work. Other than total soil replacement, I'm sorry to report that there are no practical alternatives to balancing the pH.
Magnesium sulphate works by stabilizing ions/minerals for the plant to use. The magnesium ion is crucial for photosynthesis as it is analagous to the central role that Iron plays in the human hemoglobin molecule. The sulphate ion can stabilize (a.k.a. hold on to) other minerals that a plant can use (ie calcium, magnesium, potassium). Sounds like all the stuff in fertilizer huh.
Pre-mix your soil with a cup of epsom salt, and water with a teaspoon of Epsom in 1 gallon of water once per month. Do not overwater as this will leech away the soluble minerals.
Thank you for this info. A
Though I have amended ,most of my beds with organic material I think I'll stay away from the Epsom salt. I did share this with friends in Northern CA