To improve the soil add compost.

To kill the grass cover the pile with plastic for a few weeks to smother and cook it. An excellent way to make compost from unwanted sod is to pile the sod on a plastic sheet and when finished, wrap the plastic over the sod and leave in the sun for a month. Poof, you have compost.

i did it in a bed that was nothing but leftover construction material. Now, the soil's the best in that area.

Here are the basics: leave the grass as it is. layer it with newspaper (it will kill the grass/weeds and work wonders for the soil). then add anything you would to a compost pile: sand, soil, kitchen waste, peat moss, manur, coffee (i went to Starbucks 2/3 times a week), garden waste, etc etc. i even threw in the weeds. basically, the more the better.

then let the winter do the work. next spring, you'll have great soil.

if you're impatient like me, you can even plant in it now.

but they've got it right- this is just doing what mother nature does, faster.

there will be some wheel-barrow and shovel work to do in the spring (to terrace the pile, you have to inset the stones/blocks/lumber/whatever a bit, or it will just fall apart in a year or two)

but I add about 2" of good humus a year to my garden- which is what's left from 8" or so of mulch, grass clippings (I get them from the neighbors who 'do' lawns) and old leaves.