Water soluble fertilizers used in the float system should contain most of the nitrogen in a nitrate form.  High amounts
of urea based nitrogen can be extremely damaging to float plants.  A test conducted at the University of Kentucky
confirmed what producer saw when a fertilizer with an analysis of 20-10-20 was sold that contained most of the
nitrogen from urea.  Most float producers still use a 20-10-20 analysis, but with the predominate nitrogen source
from nitrate.  Affected plants will languish from the start and may take on an almost translucent look to the leaves due
to ammonia toxicity.  The old 20-20-20 that was initially used in the float system is now not recommended due to the
high amount of urea in this type of fertilizer.  Plants fertilized with 20-20-20 may show signs of nitrogen deficiency or
ammonia toxicity,  but not to the extent of the plants in the picture below.

(It's easy to tell which plants in a test were fertilized with the right source of nitrogen, nitrate.)