If this topic fascinates you I highly recommend these links
This first link is particularly good about describing interactions and in depth pathology. Read this when you have time to absorb and comprehend the information presented.
Plant Physiology - Chapter 5 -Mineral Nutrition
Blue Planet has done a good job of presenting photos for identification, and present quick reference to nutrient interactions.
Blue Planet Nutrients
The best site I know of for pictures of nutrient deficiencies is
|Calcium deficiency - Blossom end rot|
Hollow stem in broccoli is related to boron deficiency.
Nutrient Antagonism and Interaction
GrowOrganic Peaceful Valley has a good http://youtu.be/CLFbwByeb9k
I found this conversation interesting. Alan from BioNutrient.Org talks about soil building and how soil health effects our health.
Alan Chartockin Conversation with Dan Kittredge