every plant i have now are losing leaves as they ripen...nothing to do with N deficiency. it's normal...
and when you tested your soil hopefully you took samples from all over and at different depths...otherwise your test is only good for that one spot you chose.
that leaf curl could very well be a sign of too much water...at this time watering should be cut in half, at least. i also wouldn't put any more additives around them...looks like they've got plenty to see em thru to the end.