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btphelps

New Member

Posts: 4

Location: USA

1

Sunday, August 7th 2005, 6:04pm

Dead patches in grass -- inadequate water?

I have an area of lawn about 60x40 that has had a consistent dead patch in one area since we moved in 1 year ago, and now additional dry/dead spots have appeared. The soil is mostly clay. I aerated 11 months ago and again two weeks ago. I fertilized last fall, this spring, and again after I aerated two weeks ago. I am planning to reseed, but want to fix the problem first.

1) I think the zone may have too many heads. While other lawn zones have 6-7, this one has 10. The heads are Rainbirds (T-Bird T-40 Part Circle). I've checked and adjusted the spray pattern of the heads earlier today. Most of the dry areas appear to have been received less than optimal coverage.

2) I am on a well. Before the sprinklers kick in, the 88 gal tank is at 62 PSI, and the sprinklers are covering the area just fine. After the sprinklers are on for a couple of minutes, the pressure drops to 20 PSI, and the sprinklers cover about 1/2 the arc they were covering at first. The well pump is 15 years old, and I wonder if it might be at fault. (The well and pump tested OK 1 year ago when I bought the place.)

3) With no other water on, the hose will fill a 1 gal bucket in 5 seconds; with the sprinklers on, 12 seconds. The sprinklers put out about 1/2 inch of water per hour. I was running this zone at 25 minutes 3x/week, so the lawn might not have been getting enough water. (We live in the Central Valley, outside Stockton, CA, and the avg temp this time of year is about 95 every day. [8D])

Here are pictures of two areas of the lawn from last July, each accompanied by a picture from today. You can see the lawn has many more brown spots.

The first is looking south-southeast. Note the much bigger brown spot under the tree in the center from last year to today:

Last year:


Today:


The second is looking south-east from the same location. Note that there is a small grove of Sequoia trees in the background of this picture:

Last year:


Today:


Maybe I've identified and fixed the problem by adjusting the sprinkler heads. But maybe there's something else I should look at. Any recommendations/suggestions are sincerely appreciated.
Brian T. Phelps
http://garnica.phelpsinc.com

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

2

Monday, August 8th 2005, 3:53am

Does the pressure stay at 20 psi? Normally, you want the pressure control switch to trip at about 40 psi, and for the pump to run continuously while the sprinklers are on. It might be necessary to change some nozzles on the heads to achieve constant running.

btphelps

New Member

Posts: 4

Location: USA

3

Monday, August 8th 2005, 10:17am

Thanks for the response!

Yes, the pressure stays at 20 PSI. The pressure switch does kick on at about 40psi, but as it's filling the tank, it's not maintaining that PSI, and it continues to drop to 20 PSI. The sprinklers do run continually, it's just the heads lose about 1/2 their arc or spread.

If I changed nozzles, what would this do? Reduce the amount of water a nozzle uses so the higher PSI could be maintained? Would I then just water for longer periods?
Brian T. Phelps
http://garnica.phelpsinc.com

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

4

Monday, August 8th 2005, 1:59pm

That's correct. You want the pump to be operating at higher pressure, so you have to swap nozzles where necessary, to bring down flow, and bring up pressure.

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

5

Monday, August 8th 2005, 1:59pm

That's correct. You want the pump to be operating at higher pressure, so you have to swap nozzles where necessary, to bring down flow, and bring up pressure.

btphelps

New Member

Posts: 4

Location: USA

6

Monday, August 8th 2005, 3:42pm

Any suggestions on what I might use instead?
Brian T. Phelps
http://garnica.phelpsinc.com

RidgeRun05

Supreme Member

Posts: 314

Location: USA

7

Monday, August 8th 2005, 5:24pm

As far as nozzles go? What type of nozzles are you currently using?
Tony Posey
Ridge Run Landscapes

btphelps

New Member

Posts: 4

Location: USA

8

Tuesday, August 9th 2005, 2:56pm

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by RidgeRun05</i>
<br />As far as nozzles go? What type of nozzles are you currently using?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Rainbirds (T-Bird T-40 Part Circle and Full Circle)
Brian T. Phelps
http://garnica.phelpsinc.com

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

9

Wednesday, August 10th 2005, 7:11am

They discontinued that model, but you could start by doing a zone-by-zone inventory of the nozzles, which may be color-coded. Red=1.0 Black=1.5 Brown=2.0 Grey=3.0 Yellow=4.0 Green=6.0 - if some zones have better pressure, that will be a guide to what mix of nozzles are correct for you.

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