Drip irrigation maintenance: What you need to know

Various factors impact the success of an irrigation system. To ensure system longevity and efficiency, two factors cannot be neglected: using quality products and system maintenance. In terms of product quality, the message is clear: “You cannot afford to risk the financial viability of your project by not investing in the best possible irrigation equipment.”

For more information regarding irrigation planning and selection, read the following articles in Netafim’s series:

• Precision planning for precision irrigation
• Drip Irrigation: What you need to know
• Micro-sprinkler irrigation: What you need to know
• Open-field sprinkler irrigation: What you need to know

In this and future articles we will focus on what you need to know about the maintenance of different irrigation systems.

Irrigation and maintenance

Maintenance is crucial for all types of irrigation systems. In a pivot irrigation setup, for example, nozzles, gearboxes, electrical systems and more must be checked regularly. With micro-sprinkler irrigation systems, maintenance includes checking nozzles and adjusting sprinklers regularly to ensure optimal water distribution.

All irrigation systems consist of the same basic components: a motor and pump, filtration, valves, mainlines, sub mainlines and a water distribution component – be it drippers, sprinklers or pivots. These components need attentive maintenance. In this article we will focus on the maintenance of drippers and driplines.

Prevent clogging

A quality dripper can be defined as one that emits a predetermined flow rate that is accurate and constant over its intended lifespan. To ensure this, the dripper must be kept clean. This is why most maintenance activities and dripper features are focussed on lowering the risk of clogging.

Drippers consist of different components and each will impact a dripper’s tendency to clog:

• The filter: The size of the dripper filter will determine how fast a dripper will clog. Most of Netafim’s drippers have the largest filter in their class.
• The flow path: The design of the flow path, including the design of the ‘teeth’, as well as the width and length of the flow path, will impact the dripper’s tendency to clog. Netafim’s patented dripper designs ensure maximum turbulence to lower the risk of clogging.
• The pressure regulating diaphragm: In Netafim’s pressure compensating drippers, this diaphragm promotes self-flushing to clean dirt from the dripper. This component is included in pressure-compensating drippers only.

Click here to read about the features that impact dripper quality.

It is essential to discuss these aspects in a maintenance context, as the ‘maintenance’ of a drip irrigation system starts during the planning phase of the system.

Dripper clogging must be prevented at all costs, as it is very difficult to return flow once a dripper has clogged. Preventive maintenance is therefore crucial to ensure that drip irrigation is successful. It is also necessary to select a dripper that would not clog easily during the planning phase already and to design the system in such a way that there is enough flow to flush laterals, which is one of the most important drip irrigation maintenance activities.

Watch the following video for instructions on flushing laterals.

To simplify maintenance, it is recommended to install flush valves on the main and submain pipelines. It is also vital for each block to have its own valves and injection points so that customised treatments can be applied to individual blocks. The system must be designed with sufficient capacity to allow chemical treatments when necessary.

The first, and probably one of the most crucial parts, of drip irrigation is the filtration system. Efficient filtration prevents drippers from clogging. Filtration technology has greatly improved over the past few years, which means that clogged drippers poses less of a challenge in modern drip irrigation systems. Filter maintenance will be discussed in a separate article.

Click here to read about the selection of filters.

Causes of clogging

To prevent clogging, we need to understand what causes drippers to clog. A sample of the water source must be taken during the planning phase and sent for full analysis at a reputable lab.

Samples must also be taken throughout the year, during different seasons, to ascertain what the quality of the water looks like, as well as possible changes in quality. The composition of the water will give an indication of the risk of clogging, as well as other problems that might arise. Based on the results of the analysis, experts can make recommendations on the water source’s suitability for irrigation, changes to the design of the system, and maintenance activities that will ensure continuous and efficient operation.

The four main culprits in terms of dripper clogging is high levels of iron, manganese, total suspended solids (TSS), and organic matter.

Luckily, there are treatments to combat all these potential problems and prevent drippers from clogging. The levels of these culprits in the water source will determine the maintenance plan.

It is also important to do spot checks at regular intervals to determine how efficient your maintenance plan really is. Do a visual inspection by cutting open a few drippers in the system and then adjusting the maintenance plan according to the results of this inspection.

In the following video, Gary Frances, technical advisor at Netafim KwaZulu-Natal, explains this process:

Iron and manganese

If high levels of iron or manganese occur in the water, the best treatment is to expose the water to oxygen. This allows the metals to oxidise and convert to insoluble forms. These insoluble metals must be left to settle at the bottom of the reservoir. A suction pump can then be used to suck water from just below the surface of the water, where very little of these metals will be present, into the irrigation system.

Nitric acid, phosphoric acid or sulfuric acid can also be used as treatment to maintain the systems’ efficiency. These acids are often integrated into a fertilisation programme.

Total suspended solids

High levels of TSS in water are mainly solved with good filtration. A suitable filtration method must be selected, and the system must be well-maintained. In this context, flushing laterals to rid the system of dirt is also a key maintenance activity.

Organic matter

If high levels of organic matter occur in the water, a hydrogen peroxide treatment to oxidise the organic matter can be used. The oxidation process produces harmless carbon dioxide and water that easily move through the system.

In modern drip irrigation systems, it is common practice to continuously inject low dosages of hydrogen peroxide into the system, thereby preventing organic matter from building up in the system. This is especially important in low-flow drip irrigation systems. The hydrogen peroxide dosage is adjusted according to the levels of organic matter in the water and the changes in these levels between seasons.

Subsurface drip irrigation

Subsurface drip irrigation, where driplines are installed below the surface of the soil, offers various advantages and are increasingly being used. Subsurface dripline installation, however, increases the risk of clogging due to root intrusion and dirt being sucked into the dripper.

These problems can be prevented through chemical treatments or choosing the correct dripper. Netafim’s AS XR solution takes our already advanced Uniram™ and DripNet PC™ drippers to the next level with anti-siphon and extra-root protection. A copper coating on the dripper cover prevents root intrusion and a special anti-siphon mechanism prevents dirt from being sucked into the dripper.

Taking care = carefree

As is clear, system flushing and chemical treatments are two vital keys to the success of a drip irrigation system. Maintenance must be done preventively to ensure that systems operate efficiently for as long as possible. If the necessary maintenance activities are done sufficiently and successfully, you will be able to grow more with less without a care in the world.