How does the process of irrigation work?

Story by Geoff Geddes

Irrigation systems can take many forms. "The most basic system is flood irrigation, where a field is completely leveled and graded to the point where it can be flooded," said Tyler Duncan, treasurer for New Way Irrigation in Lethbridge County, Alberta. "You then lay out pipe with gates that you open to turn on the water and flood the field."

A step up from the flooding approach is the wheel line. A series of pipes with sprinklers along its length are fixed to wheels of about 1.5 meters in diameter, and a large hose provides water at one end. Once a portion of the field has received enough irrigation, the sprinklers are moved to a different area and the process is repeated until the entire field has been watered.

"Today, most farms use a center pivot system," said Duncan. "A large PVC pipe is trenched in the middle of the field with a fixed pivot base station that waters the field in circles."

For rectangular or unusually shaped fields, the system can be augmented with corner sections to ensure complete irrigation. Although the cost of a center pivot system is greater than the wheel line, farmers find it's worth the money.

"The center pivot system is more efficient than a linear wheel move approach," said Joel Peru, irrigation agrologist, Crops and Irrigation Branch - Ministry of Agriculture with the Government of Saskatchewan. "It's also less labor intensive, as you don't have to move it to different parts of the field; it stays in a fixed area. A new center pivot apparatus will run you about $120,000, but the benefits far outweigh the cost for most operations, and the efficient application of water is a huge factor."

Because the center pivot commonly uses low pressure nozzles, less water is lost to evaporation, and there are fewer incidents of ponding as the water infiltrates the soil at a lower rate.

As with many sectors today, technology is impacting irrigation. There is growing interest in remote operation of center pivot systems, where farmers can monitor and troubleshoot them from a computer or smart phone and receive alerts when a problem occurs.

With the growing popularity of precision agriculture, some farms are opting for variable rate irrigation, which enables users to define management zones throughout the field based on soil or landscape conditions. Using sprinklers that cycle on and off, water is applied in varying amounts so that each area receives the proper amount to correspond with its needs, and there is less chance of watering too much or too little.

For the majority of field crops and specialized irrigation crops like potatoes, the center pivot option tends to be the best one. With higher value and lower acre fruit and vegetable crops, however, trickle irrigation is recommended.

"Trickle irrigation is even more efficient than the center pivot," said Peru. "It applies water from a tape with perforations in it, causing the water to slowly drip out by the plants. Producers then apply mulch on top of that to further reduce evaporation and help control weeds. These systems are commonly used in high value horticulture operations."

Those considering trickle irrigation should be mindful that it's a more labor-intensive approach, as the mulch must be removed every year and the tapes are prone to ripping and leaking at times.

Whether you're flooding, pivoting or trickling, irrigation is crucial to your business. While there are some things you can cut corners on in agriculture, a lack of water will leave you drowning in debt. ?

Geoff Geddes is a freelance writer/editor based in Edmonton. He specializes in writing articles, blog posts and website content for the agriculture industry.