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Irrigation system assessments

Drip irrigation of tomatoRebecca Shortt, Engineer – Water Quantity, OMAFRA – Simcoe

Are you concerned that your irrigation system is not applying enough water? too much water? or applying unevenly? To request an Irrigation System Assessment contact Rebecca Shortt, OMAFRA Water Quantity Engineer at 519-426-4920 (limited availability).

Australian research has shown that one of the greatest opportunities for irrigation water savings are in improving how evenly the water is spread across the field by the irrigation system.

Let’s say an irrigator goes out to apply one inch. But across the field some areas are receiving 0.5” and others 1.5”. Some areas are not receiving enough water leading to quality and yield impacts in certain portions of the field. To compensate, the irrigator may consistently set out to apply 1.5” knowing that some areas will receive the necessary 1” but others will receive an entire 2”. This is where the opportunities are for water and energy savings.

California, Florida and other states have standardized approaches to measuring the Distribution Uniformity (even application) of irrigation systems. In Ontario, OMAFRA is currently working with the California approach for irrigation system assessment.

This assessment will quantify the Distribution Uniformity (DU) (how much the water depth will vary across the field) and it will also help identify the best solutions for improving the Uniformity.

The test involves running the irrigation system for a minimum of 4 hrs, during which time the technicians will measure the pressure, flow rate and depth of water applied in several sections of the field or zone.

Some of the results we’ve seen so far have helped irrigators improve their systems. In general we’ve discovered areas in the fields suffering from under irrigation. For example:

  • A sprinkler system didn’t have enough overlap (between the sprinklers there were rows that were receiving almost no water). Changing the spacing resulted in even applications and greater productivity.
  • A drip system was not getting enough pressure at the far end of the lines – the grower knew that the far end was not getting enough water but the system assessment confirmed how much those plants were missing out.

Some changes to the system design can improve the Distribution Uniformity and result in improved quality and yield at harvest time.

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