Davej wrote:
I have always heard that cow manure is vastly better for gardening
than horse manure, but I do have a neighbor with a horse. What if I
composted the horse manure and allowed it to age for a year or two
before use?

A Yahoo search on Compost "horse manure" produced
these and other results:
whatcom.wsu.edu/ag/compost/horsecompost.htm
www.piercecountycd.org/tip_compmanure_p.html
http://www.ehow.com/how_5474391_comp...se-manure.html

Based on them, three months in the summer and six months
in the winter is adequate for horse manure in a compost
pile.

Because horses and cows are vegetarians, their manures are
preferable to that of other animals. But are manure needs
to be composted for three to six months before applying to
the soil.

Dick