Saplings vs tractors?

I agree with Texican! Brushhog. Make sure you use a clutch or shear pin in the PTO.

So, you have about 3/4 of an acre, with a plant density of around 800 trees/acre. I've cleared (by hand) 2 or 3 acres of land that had a plant density of close to 10,000 trees/acre. Have you tried taking an old axe and (with a partner to bend/lean the tree as much as he can) cutting through the roots just below the soil line? I've taken out many hundreds this way. It only takes a minute or two per tree.
Are you planning to do the sub-soiling with your 9N? Doesn't seem hardly big enough for that, to me. Any tractor with enough hp to do a good (deep) job of sub-soiling ought to not even notice a few roots.
As far as tilling goes, What kind of shape is the pasture in now? I'd be tempted to just disc a little and forgo mouldboard plowing, if most of it's still in pretty good shape.

SteveL- the field is mainly flat, but was cleared years ago (20-30) and just left as pasture- never worked in any way. Drainage is poor and the field is compact, it is in need of serious subsoiling.
It needs to be tilled and even disked as you mentioned multiple times (over a few years likely) to even it out. Looks flat but it's a very bumpy ride while in the truck/on tractor. Tilling should grade it to be more even.
My 9N would die. I am just hoping to find someone to do the big stuff.

Would a tiller/disker have trouble with the little stumps then? I'm guessing not but don't want to second guess any prospectice farmer willing to help!

If they really are 2.5" or less, I'd say no, especially if you get somebody in there with a larger tractor and a heavy disc. Of course, some tree species have a lot bigger root systems than others. Do you have any idea what you have?
Uhm, discing is tilling. Are you thinking about rotovating/rototilling?

Do you own a box blade? Since you mentioned the uneven ground maybe you could rip roots and grade it all the same time.

__________________
~Only the rocks live forever~

The species are red alder, cottonwood and trembling aspen, so all pretty soft and not rooted too deeply.

By tilling I was meaning rototilling/rotovating. I thought disking would leave it too uneven, but I have only used a tiny set and I bet a large tractor would leave quite a nice finish.

You could spray them with brush killer and then seed between the stems. Then after they die and turn brittle just knock them down.

Too bad your ground doesn't freeze. Even a small dozer could shear them off at ground level in a couple of hours.

The ground freezes alright. But then there's 2-4' of snow. I don't have access to a dozer though, would be cool. It's been mild so it's just a big swamp right now, wouldn't even trut the 4wd truck yet...
What would be cool is getting my own full size tractor!
It's dumping snow, looks like everything'll have to wait till spring, darn it. Maybe it'll melt but I doubt it.

We bought a farm that had about 20 acres of 10-15' willows growing on it. We just used our offset disk, went over it 3 times but you have to go the same direction each pass as you went the previous time so what's left of the tree is bent away from the tires. I wouldn't reseed it for pasture right away though, corn for a year then reseed.

They ought to come out pretty easy, then.

I'm not much on rototilling heavy soil. I think you'll be happier with deep chisel plowing and lightly discing. Is the land rough because it wasn't fitted down well the last time it was worked, or is it because of frost heaving?

Yep. I would seem you NEED a big tractor.

The 2-4" of snow wouldn't stop a small dozer from shearing the stems if the ground is frozen. The DNR in Alaska did that to create moose browse.

I've had an 8N, chainsaw, bush-hog, chains, tiller and plow. And a field of saplings.

With a little care and a lot of sharpening you can cut them off at the ground with a chainsaw. I did find this to be the most effective approach.

Second to that was a mattock and sweat. A mattock worked very well at digging up the root ball. I got really good at this. Three swings in a triangle around the stump, lean back, and up popped the central root ball and stump. Which then left me a nice little hole to stumble into later, but that's another story.

An N doesn't have the weight and traction to pull saplings out worth a darn. You just spin your tire and dig ruts. Chain to the drawbar so you cannot flip. If you hook to the top link, you will flip.

If you cut the tree down and leave a stump, you can't get a chain to hold on it. It just slips up and off. Pulling stumps is nearly impossible because of that.

A plow blade or tiller hitting tree root balls stops. Especially when behind an N series tractor. A big tractor with a ripper can handle it. Not an N, and not with an impliment.

Bushhogging worked, sorta. Left me nasty splintered stumps sticking up about 6" out of the ground. Those splinters were really good at punching through tires, shoes, etc. And since they blended into the grass well, I could trip over them superbly.