@ Coastal, good to know.
I keep thinking I need more K, but the 4-3-3- chicken manure product has given me the best results so far. Too bad it's not soluble for late season ferts in containers.
@Linda still didn't find anything on potassium runoff - all I see are the usual concerns about N and P.
http://www.fao.org/docrep/w2598e/w2598e06.htm 