home about contact us news
Information sheets   |   Elsenburg infopaks   |   Irrigation: 2

The installation, maintenance and management of irrigation systems Afrikaans | Xhosa

An irrigation system must be installed, maintained and managed correctly for it to operate properly.

Let us look at the points of interest with respect to the installation of the fittings and fixtures of the various systems.


Click to enlarge!		 Sprinkler systems
  • Install all pipes and fittings as planned, because the system is designed according to a specific plan.
  • Parts that can rust must be treated with a rust-resistant paint.
  • Place drain cocks away from roads and paint them a bright colour so that they will not be run over.
  • With permanent sprinklers it must be borne in mind that cattle like to rub their bodies against them. In this way they damage the sprinklers and the polyethylene upright pipes.
  • Rinse all main lines and pipes with spray nozzles after installation to get rid of any matter that may have entered the pipes during installation.

Click to enlarge!
  • Underground pipes must be laid deep enough for them not to be damaged by soil-cultivation practices.
  • It is advisable to place permanent markers at suitable places above ground to indicate the depth and position of the underground pipelines.
  • Points where the pressure can be measured must be set up after every control cock at a block or drain cock for adjusting the working pressure so that it is correct for the system.

Click to enlarge!		 Micro-irrigation systems
  • Black polyethylene piping that is used for the pipes with spray nozzles, must be left in the sun for a few days. This makes it soft and pliable, without any curves, which could weaken it. The pipes must not be laid straight in the furrows, but provision must be made for expansion and contraction as well as for normal soil movement caused by settling. The pipes with spray nozzles must be installed in the correct lengths according to the plan, and at the correct positions.
  • Main lines: All couplings must be clean, otherwise the sand granules can cause leakage at the couplings. Soil that is used for filling up, must be free of large stones and rubbish, so that the soil can be thoroughly compacted in approximately 300-mm-thick layers.

Click to enlarge!
  • Place the pipe with the micro-spray nozzles alongside the tree row from where the prevailing wind blows. The pipe can either be buried underground or it can be installed on 300mm-tall poles and fastened with wire. If mechanical operation is to be used, it is better that the pipes be suspended on a wire.
  • The taps for the irrigation blocks must be placed away from the orchard traffic so that they cannot be damaged.

Click to enlarge!
  • After the system has been laid out, all pipes must be rinsed before they are coupled.
  • All aboveground PVC pipes must be painted to protect them against the sun.
  • Pressure-measuring points must also be installed after every control cock at a block or drainage point in order to be able to set the correct working pressure for the system.

Click to enlarge!		 Subsequently, let us look at what maintenance of the various systems is necessary to ensure that the system will function effectively for at least the lifetime of the crop.

Sprinkler systems

  • Check the sprinklers for wear and tear, and replace springs, washers and spray nozzles where necessary.
  • Fix all leaking taps.
  • Rinse the main lines at least once in a season.
  • Replace rubbers for all quick-couple piping.

Click to enlarge!		 Micro-irrigation systems
  • The filter of the irrigation system must be rinsed regularly to ensure that it operates effectively. In the case of disc filters, the element must be removed and sprayed clean.
  • Rinse the lines with the spray nozzles at least twice a season.
  • Walk through the micro-irrigation blocks at least once a week to check for blocked or broken spray nozzles that need to be cleaned or replaced.
  • At the end of the irrigation season, the system must be rinsed with filtered water.

Click to enlarge!		 Finally, the decision must be made when to irrigate and how much water is needed.

This is called irrigation scheduling. The easiest way to determine this, is to dig a hole in the land and to feel how wet the soil is. Soil-moisture sensors, for example tensiometers, provide a more scientific method of measuring soil moisture. Two tensiometers are planted, one in the root area where most of the roots occur. This meter indicates when it is necessary to irrigate. The second tensiometer is planted just below the roots and indicates whether the farmer is over- or under-irrigating.

To obtain further information on the operation and installation of tensiometers, contact your nearest agricultural extension officer.

Click to enlarge!		 Finally, the working pressure must be correct for the irrigation system in order to avoid uneven distribution of the water. Nighttime irrigation is more effective than irrigation during the day, because the evaporation is less at night.

FH Koegelenberg
ELSENBURG / Agricultural Engineering