>Maybe wood chips are not the best choice for improving the soil, as I >suspect you'd need to supplement the nitrogen in a big way, but wouldn't >something like that be good to improve an whole area?
I think so...wood chips may require extra Nitrogen, but only for the initial
period that the wood is breaking down. For lots of people they are a good,
economical (many times free) way to improve soil tilth. It may take a season
or two, but it is extrememly cost effective.
Basically, any organic matter will have the desired effect (except maybe cedar
or eucalyptus chips which are phytotoxic and slow to break down). Wood chips,
manure, straw, grass clippings, leaves, compost--whatever you have available.
Organic matter will not only improve tilth in hard soild, but will buffer the
soil against pH changes. However you get the organic matter on there, it's a
good thing. You can adjust fertility/pH with (organic) fertilizers and
additives later--most important is to improve tilth so that nutrients and water
can penetrate and oxygen can get in there.
Sidebar: one of the things that made the American continent such great
farmland was the soil underlying the temperate forests and grasslands--very
high in organic matter from millenia of rotting leaves/grasses. Much of this
topsoil is depleted from nonsustainable farming practices: particularly
tilling fallow fields so that soil blows away and the nonreplenishment of
organic matter (using chemical fertilizer instead of manuring for fertility).
The soil eventually gets compacted and/or blows away. The stuff that blows
away is gone forever, but depleted soil can be renewed with careful management.
There is a movement among commercial farmers towards "no till" farming to
conserve topsoil. I even read a study done in Canada that showed that untilled
fields (corn) had fewer weed seeds because mice and *ants* ate the seeds over
the winter...very interesting...