Wow! Love the sound of your garden! We have a lot of black clay too. Darlin has been teasing me about my “gold plated dirt” I’ve been buying.
It took me three or four trips in my SUV to get all that dirt, and haul it from Walmart. It was on sale,but still more than I usuallly spend..
I would say it was worth it though because of all the organic material/fertilizer in it..