Designing Flexible Drip Irrigation Systems

Discussion in 'Planting, growing, nurturing Plants' started by Jez, Nov 24, 2006.

  1. Jez

    Jez Junior Member

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    In more arid areas where drip irrigation underneath mulch is invaluable for orchard and agroforestry applications, what would people suggest is the best way to install an efficient irrigation system which can adjust to the ever changing dripline of trees as they grow?

    When your trees are small they will need the drippers in one place, but that will change as they grow. What is the best way to build that necessary adjustment into the system at the initial construction stages?

    If you ring the plants (circular drip feed around dripline) then the rings will need to grow over time - would the necessary estimated 'slack' required to allow this just be left at the end of each line?

    To me, another alternative is a grid which can 'bulge' in gradually expanding semi-circles at the drip line of each tree...seems a tidier, easier to manage solution than the former, but it also seems it would be require a lot more line to do it.

    The other thought I had was putting a good sloped circular mound for each tree, so wherever the drippers were, gravity allowed the water to reach the dripline - is that a better solution than moving the lines over time...or a situation where too much water would be needed to reach the dripline than the other above solutions?

    The system would need to adjust to a wide variety of different sized trees of differing growth speeds and ultimate root spread, so that is a factor which would need to be accounted for in the decision making process. The other major variable is the fact that it's fairly sandy soil which drains quickly. And of course, the whole idea is to keep the amount of water needed for irrigation to a minimum, as most irrigation will be done from collection tanks or fertigation ponds rather than a bore or mains system.

    I've not needed to solve this problem before (having lived in high rainfall areas), so I'd appreciate any suggestions or advice.
     
  2. Peter Warne

    Peter Warne Junior Member

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    Jez,
    A fruit tree growing book I use for reference is Fruit for Aust Gardens, by Paul Baxter. He says that fruit trees have a very good internal plumbing system, and when water is needed, water delivered to any part of the tree will be circulated around the whole tree. So maybe it isn't so important to drop the water exactly on the drip line. I put in drip lines under the mulch to all my fruit trees when they were little, ending right at the trunk. Three years later I haven't changed them. I just give the whole food forest one hour of watering if we have a dry period for a week. We are lucky to have all the water we want. Perhaps I should be thinking about cutting the lines shorter so that the water comes out a bit further from the tree. Dunno, it's quite unscientific. We have had great crops of nectarines, peaches, apples and blueberries this year, considering they are still only small trees (no higher than 2 metres).

    Peter
     
  3. Jez

    Jez Junior Member

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    Thanks Peter,

    When I re-read Geoff's method in Jordan for irrigation, I noticed that he only used one dripper per tree for that install, so that evidently seems to be working very well on the efficiency scale - and in relatively similar soil to what I'll be encountering.

    I suspect this is aided by his layering of cotton cloth in the hole prior to planting, so I'll emulate that as well.

    I guess my mindset re. this task is probably being affected by another intellectual hangover from my long ago horticulture training...that trees 'need' even watering around the dripline perimeter etc...plus the crucial need for the system to be as efficient as possible.

    Thanks for your advice Peter, I hope your food forest bears you lots more wonderful crops for many years to come.
     
  4. Richard on Maui

    Richard on Maui Junior Member

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    Jez, I actually think your original thinking makes a lot of sense. If you concentrate the water at one outlet, the tree isn't going to be able to pick it all up before it leaches out of the soil, at least out of the soil where most of the trees roots are. So you'll lose a percentage of your valuable water... (I'm not disagreeing with what Peter is saying about the biology of trees, just that the tree can only collect so much water at a time...)
    It shouldn't be all that difficult to simply add on to your original setup and just extend with a coupler and more line. Right?
    Of course, it is better to water deeply less often too, right? To encourage the tree to send out lots of roots and be tough!
     
  5. ho-hum

    ho-hum New Member

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    All I have ever done is swap the initial dripper for an inline sprinkler or plugged the initial dripper and add two more away from the tree trunk on the drip line.

    I do use bore water so that dripper cleaning and adjusting dripper lines has to be done on an occassional basis. If this is done after the line has been running all night you can judge/guess how much water is being delivered and if you need to add another dripper etc.

    Something about crawling round under trees on your hands and knees seems to do them wonders too!

    floot
     
  6. Jez

    Jez Junior Member

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    Thanks Richard,

    A fair number of the trees I've selected prefer or don't mind fairly sandy soil, so I'd assume that once established they can use up what water they do get pretty quickly before it leaches out even if they only get it on one side?

    I would guess that by their nature they are able to take water up faster from wherever they can get it from...but that's just a guess. You make a good point about a tree's storage capacity being exceeded.

    What I was planning to do is put in a dedicated line just for the more tropical (as opposed to semi-arid) trees, so I might be a bit more careful getting a good spread of drippers for them, and play it by ear using just one to start with for the more arid tolerant ones.

    Thanks Mike,

    I got a good chuckle out of your last line. :lol:

    So when you plug the initial dripper and add one or two more, are you moving the main line at all to facilitate that or just placing the new ones into a part of the line which is further back from the tree and leaving the main line where it was originally?

    Are the new one(s) you add just on one side of the tree?

    I've used drippers (a long time ago when I was landscaping) which had a fairly long lead off the main line...I think from memory they were nearly a metre...does anyone know if longer ones exist?

    I guess if I could get drippers which had a few metres of length that might be worth thinking about.

    Thanks for the advice everyone...it helps a lot just to get the thinking and planning about this out of my head by discussing it with others. 8)
     
  7. Richard on Maui

    Richard on Maui Junior Member

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    Jez, the stuff I have been using, (I don't even know the brand name which makes it hard sometimes) is just this lightweight polytubing, with and you punch a hole and stick in a drip emmitter. Different coloured emitters have different rates of drip. So, your main line from your water source will be a 1" or 3/4" line , and then to each planting you reduce down to 1/2" or whatever, and either stick your emitters directly into your 1/2" line, or run the 1/4" "spaghetti tubing via some fittings in the 1/2" line directly to the plantings. You can get fittings for the 1/4" tubing that allow you to do all sorts of silly things, and they easily address the problem you are thinking about, allowing you to make adjustments as your garden grows... Of course, this stuff isn't cheap, I walk out of the irrigation supply store in town in a state of white fear sometimes actually.
     
  8. ho-hum

    ho-hum New Member

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    Jez,

    I have a standardised 19mm 3/4 inch system normally with drippers either side of the tree. I kept the poly pipe standard which aesthetically looks like overkill on small bits of garden but it means I am not carrying a range of fittings. Normally the poly finishes up under the mulch anyway.

    A lot of trees have those small sprinklers stuck straight into the pipe.

    I think the main thing is water penetration and I learned the value of good holes years ago. Also most of my mulches are grass-based and become impermeable so that sort of spreads the water too. My trees were all mulched for weed suppression purposes for the first 2 seasons and then I havent really bothered after that as they grow and self mulch.

    Nearly all of my mulch materials are composted. The trees have all been composted but I have to be careful as they can become sodden fast especially during the wet season so its well away from the trunk.

    I have, during the wet season in times past, raked all mulch/compost out from under the trees and re-composted it in-situ which works really well.
    There are a lot of advantages to this. All I input is a bit of animal manure to it and let the process re-happen. All of last seasons leaves etc used. Normally I will also have a little fire if I have too many gum leaves & sticks.

    This is done after the first rains which is around October the composted mulch is put back normally by Easter.

    It's all horses for courses. A lot about permaculture comes with observation over time and experience. The above practise will make sense to many tropical permies but would make temperate permies shudder - fancy removing all the mulch over summer!!

    cheers

    floot
     
  9. Jez

    Jez Junior Member

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    Thanks Richard,

    The drippers I recall using were made out of some sort of really flexible rubber-like line...one end punched into the main line, with a dripper at the other end of a 80cm or so line, and you could add more if you wanted to...perhaps that's the same stuff as the 1/4" tubing you mention...but they were already made up ready to go at the wholesaler we used to go to.

    I do remember that we only used to use Rainbird brand stuff as apparently they lasted the best and resisted getting clogged up a lot better...I think that's the most expensive, it was a long time ago though so that might have changed.

    Thanks Mike,

    It's amazing how different our seasons are even though we're nearly on the same latitude. We're only maybe just a month into our dry season here where I am ATM and it looks like being a pretty short one...although last year the dry went through until early February...it really only stopped raining since then at the beginning of November and we've even had a few good overnight rains since then. Not really typical wet/dry season weather here since we arrived. Makes planning a little difficult at times.

    At the new place we get around 800mm over the space of 2-3 months, so I'll have to be a bit careful of waterlogging during this period. I plan to have mini-swales in the orchard and Zone 4 area which direct their overflow to some bamboo species I'll give a try along the rear eastern fenceline as useful windbreak species. Along with some inter-planting of annual species in the swale which don't mind wet feet, I hope that I should be able to use the big downpour period constructively...I'll definitely have to try out your composting technique if there's becoming a problem with penetration or I end up having mulch and soil flowing down the swales to elsewhere!

    So much rain in such a short period...we'll probably spend as much on tanks for water storage as we do on the whole property. :lol:
     
  10. Paul Cereghino

    Paul Cereghino Junior Member

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    I'm always cutting drip lines when im digging around or transplanting. (burying food scraps after dark etc..) If you are trying to run individual emitters using spagheti tubing (1/4 inch (~5mm?)) you end up with a real tangle.

    I have simplified my use of drip by switching to a 1/2 inch (14mm?) heavy wall drip tape (netafim). It is an agricultural commodity rather than horticultural so its cheap... 150 US$ for over 1000 feet! It has inline emitters, at spacing of your choice.. 12-18" spacing gives you a wet line that is a nice compromise between trying to get everything wet and trying to target individual stems. Although I have used 3-4' spacing laid the line, then planted shrubs on the emitters... saving a lot of fuss, but this is typically where I am just getting them through the first summer until they establish.

    I run 1/2 flex pipe for supply, and then run drip tape off the supply line with T's. I just mark the start of each line with a stake of flag. If I want to move it (to establish some new stuff) I just go to the start of the line and pull it up from under the mulch, create a new 'trench' in the mulch and lay it down in a new location. Then I can just transplant on the 'wet line' and don't have to work about emitter locations. The linearity of the system can make maintenance easy as well, and the lines don't have to be strait if you like curvy-ness. I don't use the pressure compensating unless I have substantial drop.

    It just saves all the fuss of what to do with old emitters, and all that... yep... wet lines.... I love'em

    https://www.netafim-usa-agriculture.com/ ... vywall.php

    |-----X---o--.---o----.---X-----.---.--
    |
    |-----.----o---.----X---.--.-o--------X-o--
    |
    |-----.---X---.----o---.----o---.--X-----

    | = supply line
    --- = in-line emitter line
    X = main tree
    o = intercrop
    . = herbaceous transplant.

    Paul Cereghino
    Olympia, WA
    |
     
  11. Jez

    Jez Junior Member

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    Thanks Paul,

    I'll look into that. Sounds at face value like it might use a bit much water considering the soil type and with what I'll be able to store for the orchard, but it never hurts to have another idea to mull over and I really appreciate the time you put into your post.
     
  12. Ramon

    Ramon Junior Member

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    Hi Jez,
    With the agricultural pipe suggested, you could think about basically doing loops around trees and then occasionally inserting an extra section in the middle when needed (you'd need straight connectors). Then you could increase the size of the loops, and you'd only have wastage as you run between trees. Haven't tried it, bout might work. Don't forget to make your whole system a loop (or loops off a loop) to even out the pressure throughout the pipe.
     
  13. Jez

    Jez Junior Member

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    Thanks Ramon,

    I hadn't really considered differing pressures if I had looped bits and straight sections.

    I think I've got my head around how to do it (basically a grid), now it's just a matter of seeing how it works out in practice.
     
  14. ho-hum

    ho-hum New Member

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    Peter,


    This comment sparked a memory about watering one side of a tree, in this case a grape vine. https://www.abc.net.au/landline/stories/s102945.htm

    So there may be an advantage to have wonky/shonky poly driplines... :D
    From now on that'll be my story. I will be able to tell my mates I am not slack I am using ''PRD - Partial Root-zone Drying Technique''.

    floot
     
  15. Jez

    Jez Junior Member

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    Very interesting article Floot - cheers.
     

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