The control of fairy rings on garden lawns can be quite difficult. This is because there are no real effective cures apart from completely digging it out of the lawn. If your lawn has grade 2 and 3 fairy rings the problem can be masked by applications of nitrogen or sulphate of iron. These products promote a deep green colour which will help the fairy ring blend in with the lawn.
If the you have a grade 1 fairy ring again applying products to mask the colour of the green ring can help. The real problem will be the hydrophobic layer below the surface which causes the dead area. This area can be spiked and a wetting agent can be applied before the area becomes dry. This operation can be repeated as necessary. Once the area has become too dry it will be very difficult to re-wet.
The other way is to completely dig out the fairy ring. This means removing the soil to a depth of at least 30cm (12in). Then remove 50cm (20in) in front of the inside of the ring and 50cm (20in) beyond the outside of the ring. Be careful not to spill any of the infected soil onto the lawn during the removal process. Replace the infected soil with fresh soil and reseed the area.