That is the green grass formula used by golf supers and warm season LCO's that know. The color from this application lasts as well, because the ammonium sulfate is absorbed and supplies sulfur in addition to nitrogen. It is also economical at the rates being used as well. 1/2 lb ammonium sulfate + the required amount of iron supplement in a gallon of water. I use 1/4 lb ammonium sulfate + 1/4 lb potassium nitrate because I believe in always supplying potassium when N is being applied.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738