I don't know all about your situation, Don. I just know that I've never seen anyone 'here' re-apply afull load of N after a flood.

At most, if'n it was me, I'd wait & see what developed & possibly side-dress some 'supplemental' N later on.

No, I don't rust N soil tests. Tried it, saw too much variation. Some showed me 'low' where I tested right over the N strip!