The mild January has got things growing more than normal here in Western Oregon. Many sports fields are yellowing enough to draw concern. The soil temperatures have warmed to in the top ¾” to the point where the roots are actively taking up nutrients. It is still too early to consider applying a complete fertilizer but supplying the plant with a little nitrogen at this time will be beneficial and return the color. Applying ammonium sulfate at no more than 5 lbs/1000 sqft. will help bring this color back. You must be careful not to use this fertilizer if there is no rain in sight because you may get a foliar burn. The application of the nitrogen at this time will also help your turf grass out grow any damage done from the turf disease “Red Thread”.