This is great, I have had this problem with my farm as well. The high ph causes this problem- the technical term is chlorosis. Ammonium sulfate definitely solves this problem but in my experience, it is a somewhat dangerous short-term solution and I stopped using it because I drink water from my well. I found that the chemicals eventually leached into my system. Not the end of the world but going forward the past few years I use these three steps at my farm:
Short term: I dilute Southern Ag Chelated Liquid Iron with water and pour that around my plants. Results- 1 week; lasts 1 month
Mid-term: I add Monterey LG7115 Dr Soil Acidifier Granules Iron and Elemental Sulfur Acidic Fertilizer around my plants which is a slow release of the short-term step. Results- 1 month; lasts 4 months
Long-term: Build soil- this naturally will even out to give a ph of around 6. I do this with compost, biochar, and worm castings. Results for life (also cheapest)
I know I used name brands but I didn't link because I am not affiliated. I find that telling people the exact brand helps save them time but please, by all means, shop around. The main point is Liquid Iron and Iron Granules.