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New Member


Wednesday, July 18th 2012, 1:08pm

Watering trees over a large area

I am building a youth camp in northern Arizona and will be planting a large number of hybrid poplars for shade. In some places the trees run close together every 8 feet or so, other places just a few trees spread out. The water is off a well and I don't want to use anymore than I have to since I have to pump it. Many years ago I worked on a tree farm and we used drip emitters at the trees, poly to the drip emitters, bigger poly to the valves, and hard PVC at the manifolds. The spacing was dense so the runs weren't that long for each valve. The pipe between the manifolds was 2" PVC and we used a pump to keep the pressure high. That said, is that the way it is still done today. The trees will be planted all over a 20 acre parcel and I don't want to spend anymore money than I need to but I also don't want to worry about freezing, etc. The dirt is heavy clay. Is soaker tube an possible option? In the past there were issues with the pores filling with dirt more than with drip emitters. Any comments are welcomed.


Wednesday, July 18th 2012, 1:37pm

Soaker tubing coiled around the tree is one way. You can get pretty uniform distribution.
Might be more trouble than they are worth. That and some alternates are discussed at WATERING TREES.

Emitters will probably be the best way to go.
Two or three per tree.
I worked with two people putting in orchards this year. They did have uniform distribution, which is always easier.
Anyway, after all factors were considered they both went with drip emitters. Easier to regulate or change flow, easier to re-position if needed.

If you have long runs make sure you use large enough mains and get pressure compensating emitters . I've linked to one just as an example.

If you have really long runs consider putting your valve at the center and run both ways.


New Member


Wednesday, July 18th 2012, 2:26pm

Thx - Good article. What would be the max elevation difference between emitters with the pressure compensating emitters? Sound to me that those would be the easiest in the short run. Make a loop around the tree and punch the emitters into 1/2 in poly and then tie the poly runs together based on flow and elevation.
Thx again


Wednesday, July 18th 2012, 2:47pm

Depends on a number of conditions.
Assuming pumping uphill.

Head pressure = .43psi per foot.

Using that emitter I showed you as an example:

  • Operating pressure: 10 to 55 PSI.
  • Recommended pressure: 25 PSI.
Pump pressure-friction loss per hundred feet-head pressure = >10 to 55psi< then you are good.
Remember, you have to figure worst case, which is the farthest emitter, and count main and lateral pressure losses.


New Member


Wednesday, July 18th 2012, 2:56pm

So if I want 25 +/- 10 psi on a line I need all the emitters to be +/- 23 feet (10psi/.43 psi per foot). I can easily do +/- 10 feet as my property has a very shallow slope.
Thx again


Wednesday, July 18th 2012, 2:59pm

Don't forget friction loss due to pipe. It sounds like you'll have some pretty long runs.

And good luck. Hope it works out.


Supreme Member

Posts: 4,102

Location: Metro NYC


Wednesday, July 18th 2012, 4:46pm

I can only fetch and carry the idea the in a really dry climate, poly pipe will be chewed by animals seeking water, and it therefore is better to have heavy PVC upstream of any and all emitters, the only actual poly being the 1/4-inch spaghetti tubing from emitters to end points arrayed in circular patterns around each tree.


New Member


Thursday, July 19th 2012, 12:54pm

Is there an easy way to determine friction loss based on material/size of pipe and flowrate? My brother uses black poly above ground and has issues with rodents chewing through it but he also has had gophers chew through heavy PVC so I am not sure what the solution is there.


Thursday, July 19th 2012, 1:38pm

Go to FRICTION LOSS. Common PVC and Poly charts.

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