New Lawn Yellowing

Early this spring, I put down new sod. The grass looked incredibly healthy for several months. But now, although it's still very thick, the grass is starting to look yellowish. It's not underwatering, as I know the gray-green tinge underwatering causes. I have not fertililized the lawn since I laid it down (except for the starter fertilizer). I cut the grass high at the mower's highest setting, and use a mulching blade. (The mulched clippings are fine enough not to be visible on the lawn.) I deep soak the lawn three times a week. I feel like I'm doing everything "right" but still, it's looking yellowish. Any suggestions?
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Forgot to add that I'm in Zone 9 where temps have been lingering in the mid-90's with little or no humidity.
-Fleemo
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snipped-for-privacy@comcast.net wrote:

You might try letting it dry out a little between waterings. Give the grass motivation to root deeper.
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Sod never really roots. Sod is extra susceptible to every lawn malady. Sod is like hydroponic lawn. If sod is not greening up it probably needs nitrogen. It's not possible to sucessfully grow sod withoiut an automated sprinkler system. Sod requires daily watering and constant [time release] fertilizing and pesticides. Sod is for those who have no patience and have more dollars than brain cells. Sod can't compete with a seeded lawn.
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Balderdash.
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Iron? 3x per week is too much. Define deep soak? Most grass needs watering to an inch deep to encourage the roots to grow deeper. How large an area, what type of sprinklers and how long do they run? Are you on a slope? Do you use a lawn contractor?
For example:
1000 sq. feet of lawn requires 1000 x .62 gallons (.62 gallons covers 1 sf to a deph on 1 inch) gallons of water to apply an inch of water.
So, if you have 1000 SF to water, you need to apply 620 gallons of water per week (abscent rain).
If your sprinkler delivers 3 gallons per minute, you need to water the same area for 3.44 hours.
If you have a slope, then you still need the same amount of water, but it must be applied incrementally to prevent runoff.
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We used to grow annual rye for a few years then seeded perennial. Sod is quick I know I had to help a friend get it down before it self destructed due to heat buildup. Speak of composing without trying.
My question is what does your sod sit on ?

Seems like great advice!
Bill
--

S Jersey USA Zone 5 Shade
http://www.ocutech.com/ High tech Vison aid
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Just for grins, try three things: 1) Get down and look at the cut blades closely. Are the tips torn-looking or cut?
Sharp lawnmower blades leave a nice "cut" looking edge, while dull ones look ragged. The ragged edge often gives a yellowish or brownish cast to the lawn http://www.floridagardener.com/misc/sharpenyourblade.htm
Also examine the grass blades for brown or yellow or reddish spots or or pustules (a sign of fungal diseases)
2) Lift a piece of sod in the yellowest portion -- not a big piece, or very deep... what you're looking for is to see if the roots are penetrating the soil underneath, if the roots look healthy, and if you see signs of insect activity. Also check to see if the native soil under the sod is as damp as the sod. You can also check for excessive thatch buildup (though I'd be surprised if you have much in this new a lawn). At the same time you do this, collect some of the native soil underneath the sod for soil analysis if you hadn't done that before sodding. At a minimum, I'd like to see soil pH, P, K and Fe.
3) Apply some fertilizer to a small section; something with fairly high ratios of N to P and K. Watch the area for fairly immediate greening up. Be prepared to live with that spot a little greener than the rest of the lawn for a year or three if you do this ---------
What species is/are in the lawn? What have the temperatures been like, day and night?
What do the local golf course fairways look like?
My bets, without more information, are on bad mower blades, heat stress, and pH.
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snipped-for-privacy@comcast.net wrote in

How about overwatering? Did you put the sod down over a clay cap by any chance? We once put sod in our little condo yard and after a few weeks of careful watering, it went yellow and died, too. Turned out that the contractor who had built the place had scraped up and sold all the top soil so what we were left with was just clay to plant things upon/in. The clay, of course, held the water and we drowned the poor sod.
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