Micro-irrigation systems apply water slowly to the soil through emitters installed along drip lines. The lines contain very small, precisely engineered flow passages. Micro-irrigation systems can distribute water and fertilizers more uniformly across a field than other irrigation methods. This is an essential factor to remember because uniformity can result in potentially higher yields, higher revenue, and reduced irrigation operating costs.
What is Distribution Uniformity?
Distribution Uniformity (DU) measures how evenly irrigation water, and in many instances, chemicals are applied through an irrigation system onto a field.
While a DU of 100% would be ideal, economic considerations make this unattainable. A target DU of .92 or 92% (or higher) on a drip irrigation system is accepted as an excellent design.
While many irrigation systems are designed with a DU above 90%, most systems operating for even short periods will typically see their DU numbers drop below 80%. The main factor causing this dramatic reduction is emission device plugging.
Michael Pippen with Jain Irrigation provides a detailed review of what DU is and all of the factors that affect it in this video.
What causes field plugging?
Inorganic (Physical material): Physical pieces of debris like sand, silt, clay or rocks, can enter irrigation systems through breaks in pipes, the initial installation, or the filtration system if small enough and can plug emission devices almost immediately or can build up over time if flushing is not performed.
Organic (Biological material): Living materials like bacteria and algae may pass through a filtration system or grow inside irrigation tubing and get entangled in emission devices.
Chemical Compounds: Salt, manganese, iron, or a high PH can lead to potential plugging as the compounds fuse together in the drip line and block the emitters.
How to avoid field plugging?
Flush your system regularly. It doesn’t matter if you have drip hose for ten years or drip tape for one season.
Flush at the right frequency. Generally about every two weeks. Make sure the PSI is not too low also. Opening each drip line for two to five minutes during regular operation is not practical in most cases. If too many lines are opened, there may not be enough velocity to push out the material inside the lines.
Flush supply lines at higher rates than regular irrigation events. Water should be flowing at one to two feet per second at an excellent target velocity.
Let the material have time to make it through the system. In most large-scale drip irrigation systems, it can take up to 15 minutes to properly flush the entire tape lateral, even at high velocity.
To learn more on tape flushing and have a more in-depth understanding, click here to see Cory Broad – Territory Sales Manager/Product Manager for Jain Irrigation explain.
What is Maximum Flushing PSI?
Each manufacturer is different when it comes to the maximum PSI each drip line can hold. Make sure that you are purchasing the correct product for your application. If you are unsure of what your drip lines can handle for pressure, you can call reach out to me, Mike Wandzell or any sales representative at Agri-Valley Irrigation to help guide you in the right direction.
Using a run-length calculator: How to calculate data and where to find it?
A run-length calculator can help growers determine their emitter uniformity for a single drip line in a field. Jain offers this calculator for their products as well as many other manufacturers.