Living in Los Angeles, I've had to explain to a lot of people in other parts of the world some of these details (salting the earth, agility of aircraft). This summarized a lot of that data and even taught me some new things (like the fertilizer in the fire retardant).
Calfire doesn't own the larger aircraft, they lease them from providers that can move them around throughout the year, to wherever the current fire season is. This is far more cost effective, as the equipment doesn't have to sit idle in the off season, and the crew can keep current without expensive practice runs.