Let me add::
The base elements both Green Doctor, Me and a few others use, Are the more expensive sources. 46-0-0 Urea is a lot cheaper than 21-0-0 Ammonium Sulfate. etc etc.
Many years ago I saw a Picture of Jesus, the Canvas was TURF and medium was Different Fertilizers. Each element of Fertilizer cause a different type of reaction in the plant that can be expressed in the leave color. Of course this was a huge picture that was only visible from far away. The artist had to of studied fertilizer and it's effects on turf for years before doing this master Piece.
It was seeing that picture that got me interested in Fertilizer and I have studied it's effects ever since. BTW I am not a religious person so it did not matter to me who the picture was.
You can lead a Donkey to water but you can't make the Jackass Drink
"As Americans you have the right to be stupid." John Kerry
"Life is tough, but it's tougher when you're stupid.” John Wayne.