OK, this lawn obviously had a fungus problem... As it began to green up this spring I noticed partial but distinct fairy rings developing. So I did a soil test to confirm my thoughts there... and it did. Very low nitrogen levels and alkaline pH. So I applied a fungicide and waited for a rain. One came the next day. So later on I went back and followed with a high-rate Ammonium Sulfate application (21-0-0). Well that afternoon it started raining again, and we got quite a bit of rain over the following days. The 21-0-0 app was on 4/21 and a bunch of rain over the weekend. So I checked in on the lawn today 4/25. Not really the results I had expected. It has greened up some, but honestly it's more on the level of a 'post good rain greenup'. The rings in the turf are still greener, but less noticeable. I'm kinda not sure what to think. With the rain we had, I expected more "responsive" results. So I'm sorta stumped. Any thoughts?