a smidge of soil science
 

Cornell has a nice set of publications and lessons on soils and fertilization
online. Here are a few, some more in depth than others, all readable:\

http://www.google.com/search?q=soil+site:cornell.edu&hl=en&start=40&sa=N
http://www.gardening.cornell.edu/factsheets/misc/soilbasics.html
http://www.gardening.cornell.edu/factsheets/soil/fertilizing.pdf
http://counties.cce.cornell.edu/chem...blications/con
tainer-growing-amending-soil.pdf (URL broken, paste back together)
http://www.gardening.cornell.edu/factsheets/orgmatter/
http://www.hort.cornell.edu/department/faculty/good/growon/index.html
http://www.nysaes.cornell.edu/recommends/8soil.htm

Not all state ag schools do soil testing for the general public now, alas,
but this is Cornell's soil testing lab faq, typical of many.
http://www.css.cornell.edu/soiltest/about/faq.asp

If your state does not offer soil tests and you can't find a reasonable
commercial lab, check with extension services in surrounding states to see if
they'll do out of state testing. I know that Iowa State does or did do
out of state testing, but the out of state tests waited for them to work
through any backlog of in-state testing -- that's probably true of any
state lab that does out of state samples. P,K and pH and lime requirements
are a good basic starting spot for garden soil analysis. Most home gardeners
really don't need much more than that except in unusual circumstances, in
my experience.

Kay