Two online encyclopedias say "drying". I guess I am stuck with that - I was hoping for a rather technical term so I could search for agricultural drying processes without pulling up a few million unrelated hits for "drying".

'drying down' is what we use here. Sorry, it's jsut as non specific when it comes to searches.

Rosa, we may be getting somewhere. +drying +hay gives me about 200,000 hits. +"drying down" +hay gives me 233 hits. Now if I am not losing a lot of useful hits using 'drying down' then it may work.

Try this one below
search=drying down + grass hay

Here is a link that might be useful: Purdue ag extension

How about 'dessicated'

Darn it Sue I was about to suggest dessication! ;o)
That what drying flowers is referred to as and anything used for drying said flowers is a dessicant.
Mike

How about 'dehydration'.