Hi Craig.
I second James' suggestion about the winter kill green manures. It's just using winter as your seasonal chop and drop. Also, I can't stress
enough how amazingly useful Redhawk's soil threads are. He really lays it out for us.
One suggestion I find myself making constantly is for on-contour swales and sediment traps. I am glad you're thinking about hydrology, because honestly, you can set things up so hydrology does all the work for you, or you can set things up so that hydrology destroys you. I prefer the first.
I also often find myself suggesting that people get soil tests done to find out what, if anything, the soil lacks. It is much better to know than to guess.
If you haven't already, look into keyline ploughing and on-contour swales. Straight lines are great for working
land with giant machines, but can have devastating consequences (think Dust Bowl). Shaping the land into flat squares is a great way to remove all texture from the land, decrease
water infiltration, increase erosion and topsoil loss through wind and water, and increase wind dessication.
I would mark out contour lines on your property, especially in zones where you've already identified erosion or high erosion potential. If digging is in the range from easy to just possible, you might want to consider digging swales to slow water down and increase infiltration into the soil. I like deep swales, where possible, backfilled with loose organic material and any mineral amendment, biochar, or compost I want to add. These will act as soil life bastions, where it stays wettest, longest, and where soil conditions remain most stable.
If you get truly overwhelming amounts of water, and/or your land is relatively flat, you might want to consider long, shallow depressions on contour instead of swales. They will have a higher capacity, and will be better suited to moving excess water off the land (though in that case, I would also consider
straw bale sedimentation dams perpendicular to the direction of flow that would allow water to pass through, catching sediment out of the water).
Finally, if you can't dig, but you have deadfall material and other woody bits, you can create above-ground on-contour sediment traps from logs, tree limbs, and rocks. You might think that this won't do much, but in actuality, it would gather sediment deposited by wind and water, gathering bands of mineral and organic material that trap water, soil life, and eventually allow seeds to germinate and grow. You could just leave it to the pioneer species of the area, or you could design a
swale guild for your property, using the pioneers that are first on scene that like to punch down through rocky soil, and a soil improvement guild featuring nitrogen fixers and other supportive pioneer plants. Even a guild that featured, say, alfalfa and, I don't know, clovers and a
feed the birds or a pollinator garden mix would get established and start trapping even more sediment, accumulating more raw materials for soil.
If you mulched, say, with
wood chips, overtop of your sediment traps, or even in their complete absence, the mulch would trap sediment, too, building soil.
As to clearing and making changes to the land, what are your short, medium, and long-term goals on the land, Craig? Also, how do you feel about livestock?
You've probably already heard the famous
Sepp Holzer exchange about someone objecting to using pigs' rooting to till fields, or some such, that ends with Sepp's pronouncement, "...then you must do the pigs' work." I would suggest that you think about if and where animals can be used to help clear the land. What you've described sounds like land that I would try clearing with goats. If you aren't interested in it yourself, you might want to see if there's anyone in your area that grazes their goats on brush; you might even get something for the offered grazing.
Now to the meat of it:
Should you till?
I don't think so, personally, from what you've said about what's growing there, but the final determination rests on your soil test, and if you need to add anything. If, say, you lacked calcium and organic matter, but your pH was right, I would drop a three inch layer of wood chips over everything, add gypsum dust and grit in quantities suggested by the soil test (I believe Redhawk said, in one of his threads, that gypsum broke down slowly, becoming available for soil life over time, such that adding too much wasn't really an issue, so I would go heavier rather than lighter, especially if the soil particles are largely the same size, or if there were issues of excess soil water retention), and if the soil was compacted, I would do a one-pass till just to get the organic matter and amendments into the top layer of soil, and never till it again.
If the above was all true, but (lets say I had a microscope with me to check these things) the soil life was already thriving, I would use a tool designed to aerate the soil and allow the amendments on the top to sift down a little without inverting the soil structure. I know some people like broad forks for this. In that way, you can improve your soil life without killing off your soil life.
That's it for now. I hope you find some of it useful. More specific information might yield better suggestions, and we're suckers for pictures, but thanks again. Keep us posted, and good luck.
-CK