Moisture percent by weight , maximum : 2.5 Total Nitrogen percent by weight , minimum 18.0 Ammonical nitrogen form, per cent by weight ,minimum : 15.5 Total nitrogen in form of urea , percent by weight , maximum : 2.5 Neutral Ammonium citrate soluble phosphate (P205) percent by weight , minimum 46 Water soluble phosphate ( P205) percent by weight , minimum 41 Particle size. Not less than 90 percent of the material shall pass through 4 mm IS sieve and be retained on 1 mm IS sieve. Not more than 5 percent shall be below 1 mm 1S sieve