I believe sumac is a root based (rhizome) plant. If you don't get all of the root bits it will come back even worse. The only thing to do is cut close to the ground then spray it right away. Might need to consult a local licensed landscaper to get a potent enough herbicide. BoxBlade then tiller might actually make it worse, much worse.
What kind of wood debris?
Not that I mind, but you might get more specific answers if you start your own thread in a different section.
I am really enjoying your thread. I am learning about different implements and different methods of clearing land. I am impressed that you make or modify your own implements. When I was growing up my father cleared our backyard of re-growth small saplings and he used buck wheat to keep the brush from coming back. I was too young to know the reason why or how he did it but it worked.
I bought an L3301 specifically to clear land and dig a farm tank/pond. Even through it has wide rear tires, it is too heavy for lawn work as it sinks in and tears up the grass. I have 20 acres in central Oklahoma nr Oklahoma City. When I bought the house with 10 acres, the tall grass and brush was about 75 feet from the house on the sides, and 200 feet of open grass in front and about 100 feet in back. I cut it with lawn tractors. However we had a wildfire that got close so I began clearing to the west of house (prevalent wind) all the grass and brush, and clearing the trees so I could walk under them. There are no pretty maple and oaks here; it is primarily jack/scrub oak and red cedar. I did it by hand with a chain saw and cut the grass/brush with lawn tractors. I went from cutting about 3-4 acres to cutting about 6-7 acres tearing up a lawn tractor about every two years.
About two years ago. I bought the 10 acres behind me. About two acres of it was hay field but the rest of it was dense woods with sumac and heavy brush with a deep seasonal wash cutting across it. I also had about an acre of brush and sumac in the front 10. We came off a three year drought and much of the sumac was dead as were many trees. So I bought the tractor in package deal with the FEL, brush-hog, box-blade and trailer. My wife did not give me any hassles, she just chocked it up as a boy toy thing and said it was something else to auction off when I pass on (I am 75).
I dove into the brush and sumac with the tractor. I kept the loader low to find the stumps (thump) and knock down the larger sumac. The brush-hog did as designed and took off the branches of the stuff I knocked down. Using the tractor and a chain saw, I cleared about two acres and made a trail into the woods to the wash and opened a clearing there. Jack/scrub oak is nasty stuff. It grows to the ground and, on old growth; all the lower branches are dead. It is difficult to get in close to the tree to cut the branches off. However, the FEL will shear them off and I can latter trim the stubs close to the bark. In the back, the goal is to eventually dam that wash and make a big pond.
Then along comes a pipeline. Originally, they were going to cut kitty-corner across the back 10 and that is what we negotiated. However, they use bait and switch and cut across the hay field into the land I had cleared, and across the back corner of the cleared front 10 acres. They paid me more, and I was paid well. I even got paid for two hay crops I did not raise (I do not hay). The total was more than I paid for the back 10 acres. They cleared 100 foot swath through the property. There is a 50 foot easement and the other 50 is work area that returns to me. I can farm the easement if I want, but I can not dig.
The machines the pipeline people use are awesome. They have a machine that tears grown trees out of the ground If the tree is too big (2 foot plus), the machine grabs it, cuts it with a big circular saw, then twists it and lays it down . They have huge bulldozer like shredders that that cuts brush and small trees to the ground. These machines throw stuff and create the wood debris I am talking about. The bulldozers come in and clear the stumps. All this was done in a single day!
Wood debris: This is big and small; some of it is under the surface and some on top. There might be some stumps in there too. My concern is it might tear up a tiller. As they planted too late in the season their grass blend did not take. They will not be back until the spring. I guess they never heard of winter rye. I am having some erosions problems which I slowed with bales of hay. However, I might have to put in my own grass ito hold the ground hence the tiller. I was thinking of lowering the tangs on the box-blade to pull up all the wood debris and locate the stumps. The Land Pride tiller I am looking at only tills to 6 inches so I do not have to go too deep.
Sumac: Much to my chagrin, some of it is poison sumac and I found that out the hard way. The live sumac cuts like brush and is not a problem. The dead stuff is a task and I cut it as mentioned above. The big surprise here is my new Bad Boy zero-turn mower (ZTM) does as well as the brush-hog clearing brush but I can not bowl over the big stuff. Where sumac is very thick I end up knocking it down and it ends up as a mat. I mow it just like grass at a higher setting. For now, that is OK as it prevents erosion and it can be mowed over. As I am not farming it I can get away with cutting it flush to the ground with hand shears. However, if I wanted to take out the root systems out and I would probably use the box-blade as above.
Clearing: Once I have cleared it with the brush hog, I go over it with lawn tractor (now ZTM) at lower settings. I sometimes have to go in and shear off a stub or root but I maintain it just like grass cutting it every other month. However, I still have sumac sprouting up here and there which tells me the runner are still there. I have some brush and poison ivy spray from Lowes. It works like a champ on poison ivy but have not tried it on sumac. Again, I am thinking of using to box-blade to tear out roots.
Roots: My neighbors and I were clearing our fence line. He was tearing the trees out. Hardwoods come out fairly clean but the red cedar leave a lot of roots. I would level the ground and shear many of the roots off with the box-blade. The small roots can be mowed down. Since we are not going to farm it, the larger roots can be cut off with hand shears. Again, I don't know if it is the best way to do it but I would use the box blade to tear out the root system.
Rocks: I do not have rocks. I have some red sandstone outcropping but no real stones. The pipeline people hit a few of those sandstone outcropping but I have only seem about 4 chunks. I was brought up in New England. I see all the rocks you have and all I can think of is stone walls. I would die (I just might) to have some real stones.
I kibbutz with people responding to your thread. If that bothers you, send me a message and I will stop. I do enjoy your thread and pictures. I am still in the dark ages taking pictures with my phone and transferring them to a computer.
Thanks again and keep it going
Richard