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IRRIGATION FEATURE

























                                              Inside a dripper                                    Netafim dripline offer

           comes down to:                     ones that are not intended for long-term   be  able  to  emit  a  pre-determined  flow
           •   Soil type, composition, and behaviour   use.  HWD  is  more  expensive  than  MWD,   rate that is accurate and constant over its
           •   Crop requirements              which in turn is more expensive than TWD.   intended lifetime?
           •   Row and plant spacing          PC drippers are more expensive than non-PC   •   Does the supplier comply with quality and
           •   System capabilities – maximum flow rate,   drippers, and so forth.”  industry standards?
            pressures etc.                     As is clear from the selection factors   •   Does the supplier offer technical and
           •   Water availability.            discussed in this article, a variety of drippers   agronomic after-sales product support?
                                              and driplines exist, covering a wide range of   •   Is the supplier reputable?
           The most important aspect of this part of the   crops and applications.  The most suitable   •   Does the supplier have access to industry
           dripline selection process is understanding   option for the task at hand must be selected   knowledge to support you in the selection
           the way water moves in the soil on the one   and will always come with a relevant price tag.  and application of their product?
           hand, and knowing the water requirements   Neethling emphasises that dripper quality
           of the crop on the other.  The goal is to   will of course have an impact on the y axis   It  is  very  important  that  the  answers  to
           achieve optimal root zone management.  (cost) of the dripline selection graph, but   these questions are “yes”. An unfavourable
                                              should not be added to the many factors   answer to any of them can be the difference
           Dripper and dripline duos          included in the x axis of this graph. “Whether   between irrigation success and failure in the
           One  aspect  of  a  dripper’s  specification  is   selecting thin wall or heavy wall drip, the   field, despite having selected the seemingly
           whether it is to be used in heavy, medium,   most  advanced  dripper or one  with fewer   correct dripline.
           or thin wall driplines (HWD, MWD or TWD).     features, quality cannot be compromised.
           “This ties in with required dripper longevity,   It  is  possible  to  select  quality  products   Holistic decision-making
           listed under the factors to consider in   while still maintaining the optimal balance   The many factors that impact dripline
           decision-making around technical dripper   between drip irrigation performance and   selection decisions cannot be viewed in
           specifications and dripper features,” says   equipment cost.”         isolation. A holistic view of the planned
           Neethling. “A big, advanced dripper meant   Important  questions  you  should  ask   farming endeavour is required, and all
           to last a long time will logically be welded   yourself when gauging dripline quality:  aspects and how they impact one another
           into  a  heavy  wall  dripline  with  suitable   •   Is sufficient technical data available?  must be considered. The table below looks
           durability. At the other end of the spectrum,   •   Considering the dripper filtration area   at the interaction between production
           a small dripper which holds greater clogging   and turbulence coefficient, as well as the   goals and conditions, and the many dripper
           risk and is only purposed for short-term use,   features of the dripline, will the dripline   features and specifications.
           will be welded into a thinner wall dripline.”
           By this logic, long-term crop production will   Factor                     Feature/Specification
           require the use of big drippers in HWD. Short
           term crop production will require drippers in   Installation: Surface or sub-surface  Flap outlet
                                                                                      Anti-siphon
           TWD, while medium-term crops will require                                  Root intrusion inhibitors
           medium-sized drippers in MWD. It all boils   Required system longevity (seasonal vs permanent drip)  Size of the effective filtration area
           down to what the crop and production                                       Wall thickness
           conditions require.                Topography                              Pressure compensation
           Cost, performance and quality      ROI calculations (crop value and other impacting factors) All features and specifications
                                                                                      Quality considerations
           Neethling urges irrigation designers and   Possible production challenges  Flap outlet
           farmers to remember that equipment cost                                    Anti-siphon
           is a sliding scale determined by a host of                                 Non-drainage
           factors. Consider a dripline selection graph                               Root intrusion inhibitors
           where the y axis is cost and the x axis is   Crop water and nutrient requirements;   Dripper flow rate
           a composite of application, durability,   Soil conditions, plant spacing, etc.  Dripper spacing
           clogging  resistance  and  other  factors
           considered in dripline selection. “Naturally,   Precision irrigation requires a system that is designed and installed with all resources and
           movement along the x axis will result in   production goals in mind, with the aim of ensuring optimal production.
           movement along the y axis and the price will
           increase or decrease. Larger, more advanced   Text and images supplied by Netafim South Africa. This article was first published in the SABI
           drippers are more  expensive than  smaller   magazine, August/September 2024.                       n

           Check us out www.salandscape.co.za                                              Landscape SA • Issue 141  2024    21
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