Do we know that gypsum when added will do nothing useful in sandy soil? It has some properties unrelated to CEC or soil nutrients, e.g. making aluminum insoluble.
How do we know that anything added will be leached in a sandy soil? Isn't calcium relatively insoluble? Wouldn't dealing with sub soil problems require some leaching? Is a high CEC bad is this context? How do we know it's harmful to oceans or watersheds? Maybe there is clay in the subsoil, who knows.. There are clearly conflicting claims out there, even just regarding Al specifically :
"Gypsum can increase leaching of aluminum, which can detoxify soils but also contaminates
"The application of gypsum or lime + gypsum lowered the levels of exchangeable Al; also, the low proportion of Al in outflow solutions suggests the immobilization of Al as a solid phase. Except for exchangeable Al, the gypsum amendment increases the proportion of all forms of Al extracted
(bound to organic matter, sorbed to, oxalate and citrate) with various selected reagents relative to unamended samples. The amount of Al extracted increases with increase of gypsum added. The gypsum or lime + gypsum amendments increased soil productivity."
Also, the importance of being holistic and thorough - like Coleman or Soloman are - isn't lost on me. But I never planned on using this area for vegetables; I was thinking cover crops, sweet potatoes, millet or some other easy to grow crop that I have experience with. I already have vegetables gardens with mulch and cover crops being used in other places.