I put out 17-17-17 fert today and was wondering if I should add any more fert to my lawn before March 15? My soil test recommended 1lb\1000sf of N, but I'll be applying crabgass preventer next month. Should I use a liquid for crabgrass and broadleaves or use a granular with some fert mixed in with it? I live in the Piedmont of North Carolina. Any help would be greatly appreciated.