Agriculture Reference
In-Depth Information
be. For example, a phosphorus deficiency shows up as reddish or purplish color on the un-
derside of leaves, but magnesium deficiency can also cause this. Nitrogen deficiency
shows up as yellowing leaves, starting with the lower leaves, but this can also be caused
by moisture issues, cold weather, disease, and other nutrient imbalances such as a sulfur
deficiency. That being said, some people use visual cues successfully along with other
tools such as testing, so perhaps I just haven't tried hard enough.
