Looking for guidance on what I can do with my lawn to green it up.
Backstory
Bought home in March 2012, lawn was green. Was told that the previous owner had a lawncare company treating the lawn, but i don't know why or for how long. Over the summer the area you will see in the pictures basically got 100% sun (also the brown grass has like no weed growth, but the green area does have some assorted grass and weeds. Into fall the brown area is larger and actually goes out of frame and down a small incline to the right. I believe there is an underground stream that runs under this area more or less as well.
About a month back I put a heavy nitrogen fertilizer down on the area to help green it (something like 50/0/0) and dethatched it by hand, hoping it was just thatchy. The area slo got a lot of rain from superstorm sandy, so I'm not sure if it's a water issue or not.
My question being, is there any more product I should put down before winter other than that heavy nitrogen fertilizer? I haven't had the soil tested, but it seems odd that the grass in that area is so much different than the grass to the left. I can provide any more insight if needed.
Also how long would I need to wait for the fertilizer to green the grass up? Is it a matter of waiting until spring to see the results of it?