By: Joel Peru, PAg, CCA, Irrigation Agrologist
In Saskatchewan, the most commonly used irrigation systems are centre pivot systems, due to their cost effectiveness and efficiency. Centre pivots are much more technologically advanced than older wheel move or flood systems, although there are still more effective methods for applying water to a crop. Subsurface irrigation systems apply water directly to the crop root zone using buried tubing that slowly releases water through perforated holes. These systems are typically used for higher value crops due to their cost, which is higher per acre than that of a centre pivot system. A subsurface irrigation system costs more than double a pivot system to install over the same amount of land.
Subsurface irrigation systems have many advantages that might be attractive to Saskatchewan growers. Its main advantage is water use efficiency, which is higher than any other system available. It is estimated that 20 per cent of water applied through a centre pivot system is lost due to evaporation and runoff, while subsurface is nearly 100 per cent efficient. While most irrigators in Saskatchewan have access to plenty of water, in some areas this higher efficiency may allow producers to irrigate more land with their water source. Since less water is being applied at lower pressures than overhead irrigation, less energy is required, which saves energy costs and benefits the environment.
Overhead irrigation systems wet the entire crop canopy, which can create a perfect environment for disease to thrive. Since subsurface irrigation applies water underneath the soil surface, adding excess water to the crop canopy is not an issue. Other advantages of these underground systems are that they do not create obstacles in the field and are less affected by field topography, which allows oddly shaped fields to be irrigated.
Besides subsurface irrigation’s high initial cost, there are other disadvantages that should be considered. These systems allow producers to apply water as often as necessary, but producers with a water supply that is not available for the entire growing season will not be able to take advantage of this benefit. Seed germination poses a challenge with these systems, especially in sandy soils where water cannot travel far by capillary action. This could be a major issue for shallow-seeded crops like canola during dry springs.
Subsurface irrigation is a very efficient form of irrigation that is used all over the world. For Saskatchewan growers, the added cost of this investment would only make sense for high-value vegetable and potato crops. As Saskatchewan producers continue to strive for sustainability and use environmently friendly technology, subsurface irrigation should continue to be considered for wider adoption in this province.