Salt Deposits from Evaporation
Fertilizer salt can be deposited on the surface of float trays if float water
is fertilized prior to seeding. As fertilized
water evaporates from the surface of the tray, especially the dividers between trays, salts are left behind and may
be a brownish, reddish or white in color. The grit of the salt can be felt in most cases..
(photo taken by Steven Heightchew)