I don't know what to do about the soil, but I made a raised bed where an old maple tree came down after burning out the stump. Things went well for about 5 years and then the garden started sinking big time. The monster roots were finally decomposing and leaving hollow pockets. Last fall I had to move all the perennials from that garden to the vegetable garden where they spent the winter. I dug around down deep and added a bunch of dirt and compost last fall. I'm about to move everything back (that made it thru the winter) but I just found 2 places that my shovel sinks in too easily. I guess it will continue to settle for a while longer.

Given what we know today burning stumps is not a good idea since that sends large numbers of pollutants including carcinogens into the atmopsphere. If chipping the stump out is not an option boring into the stump and pouring a high Nitrogen source in those holes will aid in speeding up the digestion of that stump. Until that happens you can spend some time making a good, healthy soil around there so what you do plant has a chance to grow strong and healthy.

There are two ways to deal with this:

A. You can calculate the rate of decay of the leftover wood buried in the ground, and the volume of the void when the stump is gone, adding some fraction for the roots that are connected to the stump, and the number of years for complete decay, as opposed to partial decay, using the formula Y(in years)=V(volume of wood, in quarts)x (moisture, over the entire year [more in spring and summer]) x diameter of the circle of the stump /amount of soil covering the stump, thus assisting in the decay (in inches) with a correction for additional soil added.

Or,

B. You can say "that wood in the ground is not growing any more, and will be rotting away for a few years, and I"m going to have to add dirt, from time to time, to keep the area level".

Most people pick B.

Thanks, jannoel - was curious about the approx time til the soil settled. I figured at least 4 years.

Let me rephrase my question. Forget the stump. My question is about the soil which has been under a spruce tree for 30 years.

Question: What do I add to the *soil* which was under the spruce tree to make it good for flowers now?

I've read several techniques for getting rid of tree stumps - one of the most intriguing is the Amish, who apparently dump a whole big pile of manure on top of the stump, and it just goes away in a year or so.

I have had to remove 7 large willow trees from my property over the past 5 years. Generally, I cut them off as close to the ground as possible, drill numerous, 1/2" dia holes in the remaining stump and fill those with potassium Nitrate (saltpeter) which is sold as "stump remover", and leave it for a year. I've tried to burn it; the saltpeter is, theoretically, supposed to turn whats left into some thing more flammable than soggy roots, but lets say my results don't live up to the hype. So on a lot of the stumps, I continually fill the drill holes with a high nitrogen fertilizer, which seems to help the decay, and I plant grass all around. It takes a year for the grass to get established. About 3 years down the road, I'll see a huge bloom of mushrooms coming up all around where the roots were. The stump is still there, but I have to really look. I don't notice much soil slump, so much of the root ball must still be there or something, however there was no bulge when the tree was growing either.

The last one, a 5' diameter tree that was shading the front sidewalk and driveway in the winter thus creating a skating rink and numerous falls, I cut down, drilled, and put, over a summer, 3 lbs of the saltpeter. That winter, I lit it off and using a reversed shop vac, so it served as a blower, burned the thing out, 2 ' down, in two days. Clouds of sparks in the snowy night. I filled that with top soil, and thats now a slight mound with grass growing all over it.