Mel’s mix in 1 4x4 and the other one a combo of peat moss, compost and vermiculite.
Yep - that’s what I thought. My mel’s mix has done better in subsequent years with growing winter rye or wheat and turning under as well as adding plenty of compost each year.
It might be worth a try to add some more compost as a side dressing, maybe even some bone meal, blood meal, and throw on a few banana peels and crushed egg shells.
Have you tried any water soluable fertilizers?