Precisely why I keep nearly the whole lineup on hand at all times. Also why I originally bought it when you could still buy quarts. So I could patch in whatever the plants needed if I had a deficiency. If you wait til you need it to order it's no good. Sap analysis says it'll show a week before you'll see it in the plant you can detect it in the sap. Got to be on top of things...
FE: Do you actually use the sap analysis? Nobody seems prepared to answer my questions in that thread, so maybe you can make it make sense to me here.