Hi Heyruthie. Sorry to hear about the overgrazed hillside.
I would look to nature's first responders. What are the pioneer weeds in the area? It is my opinion that you might want to get living
root masses onto that hill as soon as possible, for fear of losing your hillside to erosion.
If you're pasturing animals, I would put the area into regenerative pasture, using your pioneer species and green manures, as well as any livestock-specific forage you can use.
I would also have a comprehensive soil test done. Check to see, even just with a shovel, and with your eyes, how much organic matter is present in the soil. Look at the particle size. Are they all tiny and the same size?
Without knowing the specifics, I think a number of things might be going on considering what you've told us. I think you might want to drop at least three inches of organic material on that spot, and amend with the rock dust that best suits your soil's needs. If it was calcium, which is common in certain types of water-impermeable clay soils, I would suggest gypsum grit and dust.
I would then broadfork it in. You could probably till it in, as a one-time deal. If you have no soil life to kill, there's no problem inverting the soil structure, as it's just dirt. Tilling it in will put those amendments into your soil, getting them to changing its composition faster.
Another thing you could do is make
compost extract.
Bryant Redhawk has a number of useful threads on this site concerning soil life, and at least one goes in depth into how to make decent compost extracts to inoculate prepared dirt to become soil. Where available, some people use a dilute
raw milk solution, and I have heard that this increases soil life and the amount of sugars in the grasses, but I don't know how it stacks up against a good compost extract, or even EM solutions.
Any other information would be helpful to focusing our responses. There are some very knowledgeable people on this site that would be happy to offer suggestions.
But good luck, and keep us posted.
-CK
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein