Ag lime is finely ground limestone(calcium carbonate). Hydrate lime is calcium hydroxide.
Here is a link that talks about it.
http://apps.rhs.org.uk/advicesearch/...e.aspx?pid=144
Hydrated lime will be very quick acting and will burn plants, think lye. I don't know if it will last the whole season or not.
The question I have is what was your garden like last year. That should give you an idea where your garden is like before you get test results.