Thank you for making such complicated chemistry and soil biology accessible to the uninitiated Gee. I don't know that we have EWC here in SA and importing is not possible. I have a local product from my aggrie, called Elemental Blend. It's meant as an amendment to used soil and as a top dress during growth. I gave the Rosemary some of that once before and she greened up nicely but it took a while and I think I'll try some calcium this time and then top dress. I'm sure it takes a while to become available if it is not dug in, the elemental blend.Talk to Azi about this one for ppm's and stuff. He has been trying it for a week or so. Check his progress to find a starting point.
I sprayed a test pot of crusty soil with 200ppm gypsum solution and it turned to dust and fried the plant so I wouldn't go over 50-60 ppm to start. It pretty much works on contact and within 48 hours you see things greening up.
"Works on contact" can be very dangerous as once contact is made its all over, a flush won't fix whats already done.
Go slow, or better yet start topdressing ewc in. Its loaded with calcium, carbon, nitrogen, and phosphorus, but all in nice friendly amounts. Try both on 2 different pots. See what transpires. Let us know pro or con.
You're a star and I found your gee journal, which I've just started reading. Please can we import your chemistry and biology and botany stuff into that thread since it is for topics such as these How would one do that?