In the U.S., some landowners can be paid a subsidy by the federal
government for not farming their land and allowing it to remain
fallow, apparently as an incentive to prevent soil erosion. The list
of those landowners is public information. A couple of years ago, I
found a website that searched a database of recipients of this subsidy
by their home address -- I found several who lived in my area, though
the land they owned was in other states. I cannot find that website
again. Sorry, but I don't remember whether it was a dot-gov. What's
its URL?

Dear jamiemccarthy,

This appears to be exactly what you are looking for:

Environmental Working Group: Farm Subsidy Database
http://www.ewg.org/farm/

It lets you search either the entire USA by zip code, recipient's last
name, or business name for recipients of farm subsidies, or you can
choose a particular state by clicking the map and then, in that state,
search by county, city, zip code, recipient's last name, or business
name. You will not only get the recipients' names and businesses'
locations, but also how much they recieved each year from 1996 to
2001, as well as the total amount of their subsidies over that time
span.
And when viewing the detailed list of subsidies recieved by a
particular recipient, you will also find "Subtotal, Conservation
Programs", split into subcategories - that, especially the
"Conservation Reserve Program", is what you are searching: Subsidies
for non-farming in order to preserve the soil and other vital
elements.

Search terms used:
"subsidy recipients" database
://www.google.de/search?hl=de&ie=UTF-8&oe=UTF-8&newwindow=1&q=%22subsidy+recipients%22+database&meta=
"farm subsidy database"
://www.google.de/search?hl=de&ie=UTF-8&oe=UTF-8&newwindow=1&q=%22farm+subsidy+database%22&btnG=Google+Suche&meta=

Hope this helps!
Best regards,
Scriptor