Why do you need to disk and till if you are building raised beds? Much easier to build the beds around the stumps and let them rot on their own.
No one in permculture that I have talked to (on line/net) believes me. However it is true that I have 4 or 5 perennial weeds that will NOT die under 8 inches of compost, they grow though & spread like fire. Had another farmer on the main road down from me use Round up weed killer & it did not kill the wild garlic, it did kill the coastal grass & wild dewberry vine, but the roots came back a few weeks later. Then there what I call sting nettle, no not the one you eat, this is a 2-4 inch tall green plant with small purple or white tomato flower & a 1/2 inch fruit that looks like a green tomato & ripens yellow. It has thorns that sting & root that came from hell, I know I got on my knees & dug half way to hell before I cut the root off & they where back next spring.
If the land Had not been my family for near 100 years, I would move.
But I degress, as an organic gardener I have to break the bottom/ hard pan from 50 years of farming, before I let it rest with pine tree for 15 years.
So now I got to kill the weeds with deep tillage & solarization, no it will not remove stumps, but it will kill most weeds & unwanted fugui, but cause I am going to use Wine cap fugus to build the soil back up after killing the weed that are not killed by tillage.
First year the beds will be single layer, I will then build up the soil over the next 5 years with sawdust/ wood clip, because that is what wine caps like & yes I will eat the flush of toad stools. So I am hoping to have stumps out by late may or early june so I can turn the soil about 8-10 inches & solarization it.
July & august are great months for that. While that is happening I need to find two or three soruces for wood chips. In my spare time plant some garlic for next Spring. The good new is that I can leave the stumps that are between the trees & bushes, as long as they are 18-24 inches from the center of the plants at the time of planting. But the beds are a different story, I was going to start on this last year & the doctor said no, but the problem is under control, now the time.