I grind mine about 8" below ground level and run my tiller thru the area later for food plots or trail cover. Pine stumps around here will last up to 20 years before becoming rotten....but I realize this varies elsewhere.
Not sure on a large area like your doing here......but I thought I would share how I have done my stumps. I would choose my method again.....as I do the long trails and such on my land. I don't get where folks use a hoe to dig large numbers of stumps out of a large area....not for me. ;)
Like many others, I think the best way to go about it is renting a mini excavator, even a very small one like mine if you are not in too much of a hurry. Much more efficient than a tractor to get a stump out.
I was clearing a small area today. I used a tool that was posted on a forum. Not sure if it was on this forum but the tool works good. I have used it many times before. I work alone so this is a slow process. Lots of up and down on the tractor.
Some of the brush that I pulled.
The largest tree pulled today. It is 4" just before the root. I pulled it out with the engine idling. I have pulled larger trees out but my tractor is on the small side so I am a bit limited.
The tool I used. It has a 6' chain. I should have used a 10' chain. I plan to add a straight rod to the end of the chain. This will make wrapping around brush and threading thru the pipe easier.
Here is some info on the bipod puller that was mentioned earlier in the thread. Again I got this info off a forum.
Is there a lot of stumps or a few? With the selection of equipment I have the dozer would be the go to option for me. 9" pine stumps would hardly slow it down. Simply push them into a couple of piles and let the rain wash them off and the sun to dry them out before burning. A few trips back and forth and you can fill in the holes. You'll want to plant grass or something else to keep the soil from being eroded. A stump grinder would be another good option but it would be slower since you would have to move from stump to stump. Also unless you'll need it in the future I don't think it would be cost effective to buy one and finding one to rent for a tractor could be hard. For larger stumps a self powered one would work but would require you to move stump to stump. You could look into renting a SS with a stump grinder attachment, could be cheaper than a dozer.