I have a 1.5acre lot in upstate NY that we just seeded last sept/oct. The grass came in really thin last year because it was to late and cold to get it to get higher than an inch or two. I added Scotts winter (4 - 15,000sqft bags). This spring (about april) my grass looked FANTASTIC, really dark green but not very thick yet. Some areas that are shaded more are nice and thick and green but the rest of the yard the grass is yellow and burnt looking. It looks like the grass is rotten or brown and dead at the base but as it gets to the top it gets greener. I am in complete sun and in pure sand. I have an inground irrigation system with rainbird 5000 heads. Last year i watered 15mins per zone (i have 16zones, each zones nozzles totaling a flow of 12GPM). Meaning to water 1.5acres i am using roughly 2900 gallons of water. I did this 4 times a day to get the seed to germinate. This year i did the same in the spring, but the rain sensor tripped when we had rainy days. I keep reading to cut back and water deep and in the morning. I changed to 20mins a zone, every other day starting at 5am until i think around noon. The grass got crispy and dried out. I now water 15mins a zone (which is a 4hr cycle) starting at 5pm, then at 10pm, then again at 3am, then at 8am. The grass is looking better but still yellow and crappy. I just put down scotts turf builder today HOPING it will come back to normal.

Can i cut back on my watering, or is it because i am in pure sand that i need to water this much. I cannot seem to water deep and get it to survie, and remember i have 16zones which 30mins takes 8hrs so i feel i have to water at night.

Or is my lawn just lacking nutrients and now that i fertilized i should be good? How can i tell when it is in need of fertilizer nice water?

What do you think?