permaculture

[<darren@permaculture.biz>]

G'day,

I've been very happy with a local (Australia) product called Leeaky Hose
(www.leeakyhose.com.au). Made from recycled tyres, this porous 13mm diameter
pipe emits water at about 2 litres/metre/hour. 1 metre of fall is all that
is required, so it outperforms any punch-in/inline drippers that I am aware
of. In terms of water quality we have one trial where laundry-water (grey
water) has been emitted through the pipe for the last 5 years without any
flushing and is working just fine. The very low pressure is the trick here.
Other similar products on the market operate at higher pressure and get
clogged up. 

We also set up a system of irrigating a 7 hectare wide spaced agroforestry
plot (rows 150m long) that is also working really well. Here dam water is
pumped 800m through a 50mm pipe to 22000 litre tank. The tank is on an earth
mound raised about 700mm. From there another 50mm main pipe is buried at 90
degrees to the start of the wide spaced tree rows. After drilling the 50mm
pipe I put in 13mm grommets and joiners to connect to the buried (200mm
deep) row pipe (leeaky hose). Because of the low pressure no joiner clamps
are required, reducing the installation cost. When commissioning the system
I pressure-tested each row pipe and found it all to be in the specified
range. Were this not the case then it is a simple matter of placing in-line
taps to reduce the flow/pressure rate. 

What is really pleasing about this system is that we only need to water the
trees once a month over summer and autumn (dry season) using between 60- 100
000 litres. If we were using a conventional dripper system then consumption
would be much higher with less production and shallower watering. The cost
of the system would also be greater as only this relatively flat site we
would need to pressurize the system (pump). This system has about 720
various large tree crop species (Quercus ilex, Q. suber, Q. robur var.
fastigiata, Q. alba, Q. rubra, Ceratonia siliqua, Gleditsia triancanthos,
Robinia pseudoacacia, Morus nigra etc.) @ 5m centres with about 720 x
Cytisus palmensis @ 2.5m centres (interplant between larger tree crops) and
1500 x Atriplex nummularia var. De Kock @ 1.25m centres b/n the larger tree
crops and tagasaste. Because of the deep wetted strip along the whole row we
are able to support more vegetation than we would if we simply had drippers.

So very low pressure, low embodied energy, low installation cost, low water
consumption, no filters/pumps etc, high water-use efficiency. Any wonder we
have another 5 kilometers or so of this pipe in the shed to put in with our
higher rainfall exotic plantings on the farm. 

Ciao,

Darren Doherty

  

-----Original Message-----
From: permaculture-bounces@lists.ibiblio.org
[mailto:permaculture-bounces@lists.ibiblio.org] On Behalf Of Rain Tenaqiya
Sent: Monday, December 05, 2005 1:00 PM
To: permaculture@lists.ibiblio.org
Subject: [permaculture] low pressure drip irrigation

I am also experimenting with low pressure drip irrigation and have been
surprised at how well certain emitters work, especially the non-pressure
compensating type.  Dripworks, in Willits, CA has information and emitters
on this topic.  I believe they have a website.
   
  As far as water spreading goes, sprayers waste water and can create fungal
problems on tree trunks.  Why not put some sort of fabric under your
emitters to help spread the water out before it soaks into the soil?  In the
Designer's Manual, Mollison gives an example of using burlap to water plants
from an irrigation canal by capillary action.  The same should work with
emitters.  Try old cloths and underwear.
   
  I'd love to hear more about your emitters and experience,
   
  Rain
   
   

                
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