If the center gets baked day in and day out, you might consider replacing some of your turf with beds or groundcovers. I have a west-facing front slope with grass that used to turn to straw every summer. I converted it to groundcovers so I no longer have to fight Mother Nature.

good idea, but the lawn is actively used for playing soccer with my nephew (and soon my son).

tim,

What is the throw distance for the rotors and the spacing of the heads? What is your water pressure? How many days a weeks is the area actively used for soccer? What height do you mow the Blue grass lawn? Is the lawn sloped at all or very much? Is the shading from the house or hedges on the perimeter of the lawn? Do you know how to do a water audit? Aloha

lawn is pancake flat. By soccer I meant toddlers kicking a ball. Grass mowed to 2 1/2". Water audit was done. Problem is that system was installed when trees were small, so every zone includes shady and sunny areas.

Tim,

Since I didn't get the data I needed to make a reasonable conclusion to your problem. My suggestion is to change the grass type to a more drought tolerant grass like Bermuda or Zoysia that can be mowed to 1" or less. This then makes a wonderful lawn to play soccer or even practice your golf game. Remove the center rotors from the lawn so people don't skin themselves sliding over them. JMHO Aloha

I would recomend decreasing the size of the nozzles at the corners and long sides while increasing the size of the two center heads. the standard ratio of size would be 1x2x4, in your case it's corner x long side x center.