The fact that the pivot works automatically and has great reliability means that the farmer may tend to forget that there are, nevertheless, certain maintenance operations to be carried out. This aspect must not be neglected even though the recommended frequency is only once a year.
The Centre Pivot irrigation method is very widespread throughout the world, because this technique has many advantages:
• automatic operation requiring very little maintenance;
• irrigation quality: perfect distribution and ideal application rate with the new generation of sprinklers;
• saving on water and energy because it operates at low pressure;
• optional new equipment allows for practically the whole field to be irrigated;
• low annual maintenance costs;
• very reliable.
What are the points to check?
The advantages of regularly maintaining the pivot. Programming the annual maintenance operations will guarantee greater reliability and a longer life for the equipment. Irrigation is a crop-growing technique and just like fertilisation or weeding it will greatly contribute towards the final yield. It is vital to avoid break-downs during the season.
The pivot’s return on investment will then be so much better.
Monitoring and control of the nozzles. This is also an important aspect to be checked because it is the nozzles that control the quantity, quality and uniform distribution of the water application programmed by the user. Apart from simply checking the system visually to ensure that it is working properly, it is also recommended that the installation’s flow rate should be checked; an increase or decrease in the flow rate could be caused by use or by a partial blockage of the nozzles. In this case the hydraulic performance of the pivot will have changed.
It is still quite difficult to provide standard guidelines regarding the frequency for changing the nozzles, sprinklers and pressure regulators.
The conditions of use are very variable and must be considered in context according to:
• operating pressures
• number of operating hours per year
• water quality
• type of sprinkler used
Generally, we can assume that the rotating sprinklers have a working life of 10,000 hours and the impact sprinklers 7,000 to 8,000 hours.
In the regions where irrigation is supplementary, the farmers push their equipment to the limit as far as the life span and performance of the sprinklers and pressure regulators are concerned, because the crop will not suffer unduly even if the installation is operating below par. However, in areas where more water is required or for higher margin crops, the producers have to ensure that the pivot is checked regularly and that the nozzles are replaced more frequently.
We can quote the example of the North-east Pacific zone of the United States where many farmers grow potatoes. This root vegetable is the primary crop rotated every 4 to 5 years with other irrigated crops. The pivots operate 2,000 to 2,500 hours per year. The farmers in this area replace the sprinklers and pressure regulators in the spring when they plant the potatoes, so as to ensure optimum irrigation for the most important crop in the rotation.
In conclusion, as with any mechanical or electrical equipment, the pivots require regular check-ups. These annual operations are very simple to carry out. On the large farms, where there are a large number of pivot systems, the farmers carry out their own maintenance and replace the faulty parts with spares that they often have in stock themselves.
For smaller units, the installation dealers organise wintering sessions for their customers.
For the nozzles, replacements are often motivated nowadays by the desire to be able to use rotating sprinklers on the down pipes, instead of the fixed spray versions. This, at the same time, allows for the pivot to be modernized by using a far more efficient technique.
