JDL would be John Deere Landscapes and yes a little care goes a long way. We dont apply anything less than 50% slow PCSCU (poly coated sulfer coated urea)If a pre is impregnated then 25% is plenty as you dont want to tie up the herbicide. All of our applications have 2-3% iron.We average 3-5 lbs of total N per 1000 sq ft for the entire season April to November.This can take from 3 to 6 total applications.