I'm afraid I don't have any advice for clearing trees, but I do have a somewhat related issue.

I've got about 3 acres in an urban area on which I'd like to start an organic growing system. My most pressing concern right now is the field, currently covered mostly with grass. The soil has been tested to be clean and healthy, but the ground is full of rocks and chunks of concrete, some very large. In some areas, it's hard to dig more than a foot or two without hitting some sizeable rocks. The middle section of the field also floods during rains.

My questions:

1) What steps do I need to take to prepare the field for planting, given all the rocks? Digging them all up by hand seems like a Herculean task. I can't afford to buy a tractor, but may be able to rent one. If I can rent one, what kind of equipment should I be looking to rent?

2) How can I increase the soil height or improve the soil drainage to prevent flooding? Dig runoff ditches maybe? The only suggestion I've heard so far is to truck in about 300 cubic meters of soil from outside sources, but this seems antithetical to an organic system.

Any help or suggestions would be much appreciated.

And if anyone here knows what zone Shanghai, China, is, that would be helpful.

emyers - somebody with a bull dozer can clean up the stumps and area in a day or two. Stuff will start to grow whether you want it to or not. To keep it from growing back up you will need to mow it with a bush hog or run a box blade over it to keep it cleaned up.

slchsu - all I can tell you is the same thing. a bulldozer or backhoe anc clean up those rocks. Maybe even a tractor with a box blade, but it could be you need to start with a tractor and then get the other for the larger rocks and concrete.

Also, the flooding issue depends on the land too. Ditches probably would help, but it still depends on amt. of rain, drainage, etc.

msmitoagain-
So you don't think cover crops will do much of anything to keep the weed population (including bahai grass) at bay until I can finalize the plan?

Cover crops will certainly help reduce weeds if they grow quickly and create a dense cover to out-compete the weeds. They can also help hold perennial weeds back. Still, you need to control the growth, whether the cover crop or weeds, and some kind of livestock to graze it can work well. Think renting some pasture to a neighbor with sheep.

Livestock sounds interesting to me first take. And, certainly I think I'll end up with some. Only problem with that (I think) is that I'll immediately need to fence the area. Not something I'm prepared to do right this minute. Really trying to get the garden part up and running first.

No one around here raises sheep.

Could you give me the reason you suggested sheep vs say a couple cows, or goats or any other "variety" of animal? What makes sheep so appealing to you? Juat not familiar with them.