[alkalinity]
Sulfur or iron sulfate is recommended most places. Arizona has so much
calcium carbonate in the soil that simply adding gypsum to help leach
out sodium (I do not know exactly how that works, not being a chemist)
may be recommended instead. Here is a writeup from the Arizona
"Master Gardener Reference manual":
http://ag.arizona.edu/pubs/garden/mg/soils/ph.html
Some vendor products in the turf industry use organic acids instead of
sulfur or iron sulfate, applied via drip or boom sprayer irrigation.
I would think in places with soils like Arizona, changing the alkalinity
of the soil itself by adding acids to react with the calcium carbonate
in the soil is like trying to empty an ocean with a bucket. What
farmers do instead in those soils is try to leach the sodium and
salts down below the root zone with deep irrigation. Mixing in a
lot of organic matter compared to what someone might need
in lower pH soils probably helps, too, providing exchangeable
ion sites on humic organic compounds that would not exist in
the native soil, but like you say, it does not last long in the heat
without a steady supply of fresh organic matter to add.
Simply adding humic and fulvic acids directly (dissolved from leonardite,
for example) may help with nutrient uptake, too, for the same reasons
(although bulk organic matter like manure and compost also adds water
holding capacity, air space, friendlier environments for soil microbes, etc).