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Open-field sprinkler irrigation maintenance: What you need to know

Maintenance remains crucial, irrespective of the type of irrigation system in use in vineyards, orchards, greenhouses or fields. To ensure that an irrigation system keeps functioning effectively and has an extended lifetime, there are two factors that should never be neglected – the use of 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.

In previous articles, we discussed the crucial steps in drip irrigation and micro-sprinkler irrigation system maintenance. In this article, the focus will be on the maintenance of open-field sprinkler systems.

Understanding open-field sprinkler maintenance

To understand the importance of open-field sprinkler maintenance, we should consider the following extract from our article regarding the basics of open-field sprinkler irrigation:

“Sprinkler irrigation can often be perceived as ineffective in terms of water-use efficiency, and wasteful if compared with drip irrigation. The fact is that certain irrigation technologies have a higher level of efficiency compared to others. This, however, does not mean that the system is inefficient. Any irrigation system that is designed correctly according to the hydraulic specifications, can achieve a high degree of water-use efficiency.”

To ensure high efficiency, as explained here, an open-field sprinkler irrigation system is carefully designed for hydraulic accuracy, in-field functionality, and optimal water delivery with the specific conditions in mind. “System maintenance must be performed regularly to ensure that the system continuously performs according to its intended design,” explains Willem Smit, Netafim South Africa’s sales manager in the southern region.

Farmers face increasing economic pressure. This pressure functions as an ongoing reminder that we cannot afford waste in a production system. “Not only can poor or insufficient maintenance lead to yield losses due to inefficient water delivery, but it can also give rise to higher energy and labour costs as well as wasteful use of water, fertiliser and other inputs,” Willem continues.

It is therefore important that we perform regular and proactive system maintenance. “We must prevent problems rather than fix them. Remember, we do not want the system to break down during a peak irrigation period. We must also prevent damage caused by problems in the system that may lead to unnecessary costs.”

Make visual inspection a routine task

Visual inspection forms an integral part of open-field sprinkler irrigation maintenance. One of the benefits of sprinkler irrigation is that the emitter can be inspected visually, so be sure to utilise this benefit. “It is important to perform regular visual inspections while the system is running. Our recommendation is to do a visual inspection at least every week. Any issues identified during physical checks must be corrected immediately.”

Do the following during a visual inspection:

  • Check that all sprinklers are positioned correctly and are actively running.
  • Ensure that there are no obstructions in the stream’s path.
  • Inspect sprinklers for possible wear and tear and replace damaged parts.
  • Check for wet spots on the main- or sub-mainlines that will indicate leaks.

Clogged nozzles may be picked up during a visual inspection. Such a nozzle must be cleaned carefully. “Be sure not to enlarge the orifice while cleaning,” warns Willem.

Diligence in design

An essential part of proactive system care is the system’s longevity, which needs to be considered during the design phase. “We must, for example, ensure that the system is designed with sufficient air valves. If sprinklers are misused as air valves, and air is pushed through the system to be released through sprinklers, they will spin too fast. Without the cooling effect of the water, this will lead to increased wear on the sprinklers.

Since uniform water delivery is a priority, the system must have a uniform design. It is also kept uniform when important maintenance activities are performed. “When you replace sprinklers or pipes during maintenance, it must be replaced with the same type and quality product. Replacement sprinklers must have the same delivery rate and be installed at the same height from the ground,” says Willem.

This prevents variation in water delivery, distribution and system pressure in an irrigation block. If variation occurs, it will harm yield uniformity.

Know your open-field irrigation system

An important indicator of problems in the open-field sprinkler system is deviation in flow rate and pressure across the system. “In order to pick up deviations and take action accordingly, it is important that you know your system. For example, actual flow rates must be checked to ensure that sprinklers are still delivering water at the correct rates.”

Incorrect pressure will not only damage the system, but will also lead to over- or under-irrigation. “A system running at too high a pressure will cause increased wear on sprinklers and will increase the evaporation rate. Too low a pressure may lead to sprinklers not operating correctly, leading to uneven water distribution.” To help keep an eye on system pressure, you can install a regulator with the necessary valves and ensure that the pressure is constantly correct.

The benefits of filtration

Although the filter requirements for open-field sprinkler irrigation are fewer than that of drip irrigation or micro-sprinkler irrigation, you must not compromise when it comes to system filtration. “Proper filtration will not only add to system efficiency and longevity since fewer blockages will occur, but poor water quality also poses the risk of yield loss. In the case of sprinkler irrigation, water comes into contact with plant leaves and water that is high in carbonates and chlorine will, for example, cause yield loss.”

Even if the best filtration system is used, there will be build-up of material in the system laterals. Depending on water quality, all laterals must be flushed from time to time. “It is an essential part of system maintenance. Flush laterals on at least a quarterly basis to keep in touch with the time it takes for matter to build up in the laterals,” says Willem.

An irrigation system is a major investment, and its maintained success is crucial to the viability of the production unit on which it is installed. Protect your investment by taking good care of it through regular, proactive maintenance.