Thursday, December 15, 2011

Drop by drip!

A couple of you had requested to post a blog on drip installation, so here are my initial thoughts and learnings. At the outset, designing and installing drip may seem to be a daunting task but once you have gone through the process, the science and technique can be mastered. Firstly, let me break down the essential components of a drip system -

1) Head Unit: This connects the water source (borewell) to water carrier system (PVC pipes). Depending on the quality of water, it may contain a hydro-cylonic filter and a disc filter to remove sand particles and impurities.

This is our head unit. Blue tank contains heavier impurities which need to be cleaned periodically. Finer impurities are filtered by disc filter (black)












Three control valves that control the water in each direction. This is IMPERATIVE (for big farms) and will save you a lot of walking.













2) Water carrier system: There is mainline that connects the head unit to the end of the plot. Typically, perpendicular to mainline are sub-main lines. The pipe size of sub-mains are smaller than main line. At the junction of main and sub-main lines is a valve to control the flow of water for a particular section of the plot.

Two valves for mango and vegetables. It is a good idea to have separate valves for each to control irrigation and fertigation.













It is always a good idea to have a bypass pipe (the one leading into the tank) to avoid high pressure and potentially bursting of pipes.
We used this while irrigating Brinjal. Area under irrigation was much smaller compared to the outflow of pump, hence water had to be pumped back into the tank (yes, not the most efficient method! )




3) Laterals: This is the pipe that actually delivers the water to the plant. There are two types of laterals - Inline and Online.
  • The former is used typically for vegetables, bananas where continuous wetting is required or roots grow laterally or the spacing between plants is close (in cm). There are built-in drippers inside the lateral pipe. 
  • The latter is used for orchard crops where the distance between two trees may be large (in meters). In online laterals, external drippers need to be attached to the lateral. The holes in laterals come in multiple spacings (30 cm, 45cm, 60 cm etc). Like wise, the drippers come in different water discharge rates - 4 Liters per hour (lph), 8lph etc. Depending on the crop, water requirement, operating time, your drip installer should be able to tell you which one is suitable.

Online dripper
















Inline dripper















  


Some DOs and DON'Ts
  1. When you are dealing in big acreages (10 acre +), it is advisable to use a JCB to dig out the trenches. Digging manually is not only inefficient but very time consuming. 
  2. When reviewing a drip design, ensure you have the ability to control water to all sections of the farm in a centralized manner. In other words, it is a good idea to have 4 'control valves' for the four directions. Closing one of them should completely shut off the water for that part of the farm irrespective of 'local valves' position. This will save you a lot of walking.
  3. You should perform 'flushing' of drip lines (both PVC pipes and laterals) periodically (once in 15 days) to avoid clogging of pipes.
  4. If you plan on inter-cropping between orchard crops, make sure there are separate pvc pipes/valves for both for fertigation purpose else you will end up fertigating both the crops at the same time. In other words, you will end up fertigating Urea on Mango and Brinjal when it is only needed for Mango. It seems common sense but a leading drip irrigation provider did not figure this before we pointed this out.
  5. Use pressure compensated drippers if your land has a gradient.
  6. At the time of irrigation, make sure the pressure valve reading does not exceed 2 kg/cm^2. Higher pressure can lead to bursting of PVC pipes.
  7. If your drip irrigation schedule involves multiple sessions (typical in bigger farms), always open the second section's valves first and then close the first section's valves. Again pressure build up can damage the pipes.
  8. It is a good idea to have a bypass valve at the water source to create multiple water sources for shadenet or labour quarter etc.
  9. If you plan on having avenue trees or trees not irrigated by drip, it is again a good idea to have water outlet points that can tapped from PVC pipes that lead to a central tank. So every time you run the borewell to fill up the tank, you can irrigate trees that are not irrigated by drip.
  10. Ensure that the laterals are not very long. More the distance from submain, lesser will be the pressure at the last dripper. Installation folks should be able to tell you what is the maximum length one can go without realizing drastic pressure loss. In our case, it was 40m. This will vary depending on the outlet pressure, topography of land, water requirement of crop etc. 
Hopefully some of these suggestions will save you time and effort. Feel free to respond with additional suggestions for other readers.

25 comments:

  1. Thank you very much. Very informative post.
    Why do we need a water tank when drip system can be directly connected to borewell.

    ReplyDelete
  2. Hi,
    Very useful post. We are also planning for drip .
    Field near Tirutani.

    1)I find few companies doing drip like Jain, Elgi, Nagarjuna..would like to know which company did the job for u and how much is the cost per acre ..

    2)we are thinking of poly house for cpasicum .. first i want to know whether it is feasibel for chennai/tirutani climate...

    3) Brinjal: how much yield are u getting ..
    What is the spacing between rows and between plants..Are u satisfied with yield of Ankur Kirti.
    We are planing for Mayhco 9 and Mayhco 11..

    4) We raised Okra seedlings Nunhams - Meenakshi
    it is showing excellent growth with protray and coco peat

    Planning for transplant with 2 ft bet rows
    and 1 ft between plants


    Regards
    Ramesh
    rameshgra@gmail.com

    ReplyDelete
  3. Raja,
    You're correct, but the borewall can run dry over time. Idea of a tank is to have multiple inputs going into it and have a buffer of water supply at all times..

    ReplyDelete
  4. Ramesh,
    1. Cost really depends on spacing, crop, design, pipes used etc, so can't give a realistic cost estimate without knowing more of what you're trying to accomplish.
    2. I have not tried out capsicum yet but I have heard it does well in krishnagiri area..
    3. Our yeild has been healthy so far, but exact numbers are confidential :) I used 60 cm plant to plant and 45 cm row to row..I would suggest 60x60 if your drip hole is at 60 cm

    ReplyDelete
  5. Hi,

    Your blog is very informative. Keep it going.

    Couldn't you have made the ground level tank ( if not overhead) so that you could use drip by pressure instead of using another pump to do the job?.

    ReplyDelete
  6. Hi,

    1. What is the reason for yield of brinjal being confidential? I would have thought that if you had a good yield, you would want to show it off :) :), or if you had a bad yield, you could advise us on where, if any, were the problems. But you said healthy, so I assume average yield. But why the confidentiality?

    2. I remember reading somewhere that you had 100 acres. Did you install drip over all the 100 acres?

    I do not have practical experience so this next question might be silly. Here goes - My relative who has a small coffee estate does inter-cropping. He said that irrigation needs for different plants are different not only in quantity of water, but also in timing. Given this fact, is it practical to say install main lines over the whole area, but lateral dripper lines over only say 5 acres block. When you want to irrigate the next 5 acres you just lift the whole lateral set and connect it to the next blocks main line. Is this possible and/or practical? I guess labour may increase, but quite marginally, whereas cost of drip irrigation might reduce substantially. Am i correct??

    ReplyDelete
  7. GG,
    Overhead tank can be pretty expensive to construct based on the size. Moreover, the pressure may not be enough if you are irrigating bigger acreages! It could work with smaller plots.

    ReplyDelete
  8. Congragats Good Going
    I just have a suggestion ,practically faced this issue while maintenance near the head tank or near the main supply junctions recommend that you dont use PVC it does not last long any maintanence work etc the PVC joints and pipes becomes brittle and you end up doing a hell of lot of work & its expensive and never can be reused.

    Rds
    Vinod

    ReplyDelete
  9. Vinod,
    Thanks for the suggestion. What material would be an alternate?

    ReplyDelete
    Replies
    1. Hi
      Sorry for the delay
      The normal GI pipe and fittings with ISI certified should hold good.
      Rds
      Vinod

      Delete
  10. Hi it could be a repeat question but still am curious.

    Why not use a overhead tank ? Infact overhead tank should help to go longer distance with drip. Regarding pressure, it can be worked out .Eg if pressure X (from borewell) gives n liters/hr then lesser pressure should give should give lesser rate, thats it.

    I think With overhead tank we could manage drip in better at least theoretically .

    Below is a interesting link on traditonal bamboo drip irrigation in nort. east region.
    http://www.rainwaterharvesting.org/methods/traditional/bamboo.htm


    Thanks & regards,
    Prashant

    ReplyDelete
    Replies
    1. For bigger acreages, I do not think overhead tank will be very feasible. Moreover, it depends on your water requirement. Constructing a OH tank with a capacity of 2 lakh liters will turn out be very expensive. Apart from irrigation, you can use SST for pisciculture and a water source is available at all times for misc activities as well..

      Delete
  11. Hi,

    Do you mind sharing the info on what brand/company you went with and what was the expense/acre to set this up?


    Thanks
    Biju

    ReplyDelete
    Replies
    1. We went with Jain Irrig and Alpha Irritech. Expense per acre depends on crop, spacing, design etc but for a normal density orchard, Rs 20,000 would be a fairly accurate (per acre)

      Delete
    2. Did u consider Driptech (http://www.driptech.com/product.html). According to this website it costs about 10,000 per acre. https://dobighazameen.wordpress.com/2012/01/25/saying-good-bye-to-flood-irrigation/

      Delete
    3. The blog stated that conventional drip sysyem costs 40,000 per acre. I would not agree with this since it really depends on the crop (orchard crop vs veggies), spacing, design etc. Rs 10,000 per acre is def. attractive but I was not convinced with the customer service after installation. For a remote place like Sivaganga, I thought it was best to go with a bigger player in the market with support presence in the area.

      Delete
  12. Have you tried fertigation thru same drip lines?
    (Cow dung is made to thin slurry,filter it and irrigate thru drip)
    Do you thin this is viable?

    ReplyDelete
  13. I would not recommend using cow dung slurry in drip system. It will end up blocking your drippers, especially the inline ones. Cleaning inline drippers is very tedious. You can use the slurry in spray systems where cleaning is not a big issue..

    ReplyDelete
  14. Can I get information about whether Driptech has lateral and inline pipes and micro sprinklers also in their product line

    ReplyDelete
    Replies
    1. I have not really looked into their product line closely, however they seem to be offering cheaper options. Not sure of the product quality though. I am sure they have a site which elaborates on their product line.

      Delete
  15. simple explanation for inline and online drippers...thank you...

    ReplyDelete
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