Lately we have been witnessing a lot of donuts in our fairways. Donuts refer to the green circles around the sprinklers with a brown ring approximately 15 ft outside of that. We are doing some experimenting with different nozzle sizes and types now before we purchase 1,500 nozzles for the fairways.
We believe we have found two solutions, but we are going to evaluate a bit more before we decide to buy. One solution is to use a different rear nozzle configuration from Rainbird. This particular nozzle configuration doesn't diffuse the water as much and keeps the area around the head more evenly distributed (see picture below).
The other solution is to remove the small opaque colored diffuser in our current nozzle configuration. At the moment there seems to be some improvement by doing this. If this works, we could save ourselves almost $4,000 in new nozzles.