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Hit the target with dripline selection

Hit the target with dripline selection

The agriculture industry’s aim is firmly locked in on precision, efficiency, and overall sustainability. This is driven by the many factors we know so well, such as rising input costs, narrowing margins, increasing food demand and more.  In this context, farmers need the right tools that must be applied optimally in order to hit the target successfully.

If you try to hit a nail with the handle of a hammer, or a screwdriver for that matter, the nail might go in. Will you however truly hit the nail on the head? If you irrigate with the wrong type of irrigation system for the circumstances, the wrong dripline for the irrigation task at hand, or use the wrong scheduling approach, can you truly harvest optimal yield, use resources with perfect efficiency and manage your crop effectively to overcome challenges? Can we hit a bull’s eye without the right tool for every job?

In the drive to promote the precise application of water and nutrients, drip irrigation is advocated as the optimal solution. Drip irrigation offers elevated levels of efficiency. Increased yield size and quality as well as resource savings are pledged as the main benefits of this irrigation method. All of this is however dependent on suitable water availability, the selection of suitable driplines and other equipment, correct installation, smart scheduling, and faithful maintenance.

Many important selection and planning decisions must be made to ensure the success of drip irrigation in the field. Of course, this only comes after drip irrigation was selected as the most suitable irrigation method, based on a holistic view of the farming conditions and production goals. Dexter Neethling, Product Manager at Netafim South Africa, lists the following as some of the important factors that should be considered:

  • Climate
  • Crop and production season
  • Soil type, composition, and behaviour
  • Water quality and availability
  • Topography
  • Electricity availability
  • Risk of diseases and pests
  • Fertiliser requirements
  • Capital and running costs of the system
  • The farmer’s knowledge and skills
  • Installation, operation, and maintenance limitations
  • Possibility of theft

Dripline Decisions

Neethling explains that selecting the correct dripline requires you to check three boxes:

  • Selecting the dripline with the most suitable specifications and features
  • Selecting a high-quality dripline
  • Balancing dripline performance and dripline cost to ensure optimal ROI

To achieve this, important selection decisions must be made in these categories:

  • Dripper type, features and specifications
  • Dripline wall thickness
  • Dripper flow rate
  • Dripper spacing
  • Dripline supplier

Dripper Deliberation

Since the start of drip irrigation innovation in 1965, dripper technology has come a long way - widening the possibilities of its application, enabling victory over challenges in the field, and increasing the precision with which water and nutrients can be applied.

According to Neethling an important part of dripline selection is considering the many innovative dripper features, and determining which attributes are required for the task at hand. “Of course, it is important to only get the bells and whistles that are truly required to overcome the unique challenges of the production unit, keeping cost-efficiency in mind.”

Dripper Features:

  • Pressure compensation
  • Anti-siphon
  • Flap outlet
  • Root intrusion inhibitors
  • Non-drainage

Beyond dripper features aimed at overcoming specific challenges, Neethling reminds us that every dripper has certain technical specifications that will determine both its suitability to the application and how well it can do its job. “These data points contain crucial information for the irrigation designer when doing the math during the design of the drip irrigation system.”

Technical Data:

  • Size of the effective filtration area
  • Working pressure range
  • Filtration requirements
  • Turbulence coefficient
  • Pressure exponent
  • Head loss
  • Dripper size (longevity)
  • Wall thickness suitability

To make optimal decisions around a dripper’s technical specifications and features, Neethling lists the following as impacting factors:

  • Installation: Surface or sub-surface
  • Required dripper longevity (seasonal vs permanent drip)
  • Topography
  • ROI calculations (Crop value and other impacting factors)
  • Possible production challenges

Inside a Dripper

Dripper Delivery

Beyond selecting the correct type of dripper, based on the features and characteristics discussed here, Neethling goes on to explain that two other very important decisions must be made to ensure water and nutrient delivery can be in line with requirements. These are:

  • Dripper flow rate
  • Dripper spacing along the dripline

These two decisions are impacted by a host of factors and many important pieces of information must be collected in order to determine the correct dripper flow rate and spacing.

To view it broadly, it all comes down to:

  • Soil type, composition, and behaviour
  • Crop requirements
  • Row and plant spacing
  • System capabilities – maximum flow rate, pressures etc.
  • Water availability

The most important aspect of this part of the dripline selection process is understanding the way water moves in the soil in question on the one hand and understanding the water requirements of the crop on the other hand. Neethling emphasises that the goal in sight is to achieve optimal root zone management.

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Dripper and Dripline Duos

As listed under technical dripper specifications above, one aspect of a dripper’s specification is whether it is to be used in heavy, medium, or thin wall driplines (HWD, MWD or TWD).  “This ties in with required dripper longevity, listed under the factors to consider in decision-making around technical dripper specifications and dripper features,” says Neethling. “A big, advanced dripper meant to last a long time, will logically be welded into a heavy wall dripline with suitable durability. At the other end of the spectrum, a small dripper which holds greater clogging risk and is only purposed for short-term use, will be welded into a thinner wall dripline.” By this logic, long-term crop production will require the use of big drippers in HWD. Short term crop production will require drippers in TWD while medium-term crops will require medium-sized drippers in MWD. “Once again, it all boils down to what the crop and production conditions require.”

The Netafim SA Dripline Offer

Cost, Performance and Quality

Neethling urges irrigation designers and farmers to remember that equipment cost is a sliding scale determined by a host of factors. Consider a dripline selection graph where the y axis is cost and the x axis is a composite of application, durability, clogging resistance and other factors considered in dripline selection. “Naturally, movement along the x axis will result in movement along the y axis and the price will increase or decrease. Larger more advanced drippers are more expensive than smaller drippers that are not intended for long-term use. HWD is more expensive than MWD, which in turn is more expensive than TWD. PC drippers are more expensive than non-PC drippers and so forth.”

As is clear from the selection factors discussed in this article, a variety of drippers and driplines exist that cover a wide range of crops and applications. The most suitable option for the task at hand must be selected and will always come with a relevant price tag.

One aspect of dripper selection has not yet been mentioned in this article. Although we should in fact not bundle it in with dripper features and specifications. Neethling emphasises that dripper quality will of course have an impact on the y axis (cost) of the dripline selection graph but should not be added to the many factors included in the x axis of this graph. “Whether selecting thin wall or heavy wall drip, the most advanced dripper or a dripper with fewer features, quality cannot be compromised on. Although it might not seem so, it is possible not to veer from selecting quality products, while still maintaining the optimal balance between drip irrigation performance and equipment cost.”

Neethling shares a list of important questions you should ask yourself when gauging dripline quality:

  • Is sufficient technical data made available?
  • Considering the dripper filtration area and turbulence coefficient, as well as the features of the dripline, will the dripline be able to emit a predetermined flow rate that is accurate and constant over its intended lifetime?
  • Does the supplier comply with quality and industry standards?
  • Does the supplier offer technical and agronomic after-sales product support?
  • Is the supplier reputable?
  • Does the supplier have access to industry knowledge to support you in the selection and application of their product?

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It is very important that the answers to these questions are yes. According to Neethling, an unfavourable answer to any of these questions can be the difference between irrigation success and failure in the field, despite having selected the seemingly correct dripline.

Holistic decision-making

This article discusses the many factors that impact dripline selection decisions in silos. In reality these factors cannot be viewed in isolation. An holistic view of the planned farming endeavour is required, and all aspects and how they impact one another must be considered. The aim is to make a comprehensive decision about all the variables that impact crop production success. Have a look at the table below, to consider the interaction between production goals and conditions and the many dripper features and specifications.

Factor

Feature/Specification

Installation: Surface or sub-surface

Flap outlet
Anti-siphon
Root intrusion inhibitors

Required system longevity (Seasonal vs permanent drip)

Size of the effective filtration area
Wall thickness

Topography

Pressure compensation

ROI calculations (Crop value and other impacting factors)

All features and specifications
Quality considerations

Possible production challenges

Flap outlet
Anti-siphon
Non-drainage
Root intrusion inhibitor

Crop water and nutrient requirements
Soil conditions, plant spacing, etc.

Dripper flow rate
Dripper spacing

Let’s conclude with the following concept of precision irrigation: Precision irrigation requires an irrigation system that is designed and installed with all resources and production goals in mind, with the aim of ensuring optimal production. Without the correct selection of driplines and other irrigation equipment, as well as the correct operation, management and maintenance of the system, precision success cannot be achieved.