By: Joel Peru, P.Ag - Irrigation Agrologist, and Chloe Montreuil, Summer Student
With intensive irrigation, producers are able to apply water to their crops when—or if—required. Consequently, irrigation scheduling is important to maximize crop yields and ensure sustainable water use. Proper irrigation scheduling will improve a farm’s profitability and efficiency by maximizing crop yield and quality, decreasing water lost through deep percolation and runoff, and optimizing pumping costs. Determining when to irrigate during a growing season is dependent on many factors. The importance of these factors is crucial for producers to maximize the return on their investment.
Irrigation scheduling can improve a producer’s profit by maximizing crop yield and quality, decreasing water lost through deep percolation and runoff, optimizing pumping costs, and improving water use efficiency. Scheduling irrigation successfully requires four pieces of key information:
- Soil texture;
- Water holding capacity of the soil;
- Soil moisture content; and
- Crop water use at the specific development stage.
The capacity of the irrigation system is also something to be considered. Different crops will use different amounts of water throughout the growing season. For example, canola can use 7 mm/day during pod fill, but will only use 2 mm/day during the rosette stage. A crop such as peas will use a maximum of 6 mm/day during pod development and will not use more than 2 mm/day until June, if planted on May 15.
The three methods of irrigation scheduling involve plant-based, soil-based and crop water use- (evapotranspiration) based methods. Soil-based methods are desired in Saskatchewan, as they predict water requirements before drought stresses occur. Soil moisture measuring is key for the soil-based method, as it determines the volume of water currently available to the plant. Once an irrigator knows the amount of water available in the soil and the evapotranspiration rate, the timing for the next irrigation can be estimated. The three methods include: the feel method, the moisture monitoring equipment method and the computer model and weather data information method. Irrigation scheduling is a cheap practice that often only requires a couple of rain gauges, a Dutch auger, and knowledge on you crop and soil properties.
For more information or assistance, contact one of the Ministry’s Irrigation Agrologists at 306-867-5500. The Ministry of Agriculture and the Irrigation Crop Diversification Corporation have also jointly released the first update to The Irrigation Scheduling Manual; the publication is also available in print format, which can be picked up at the Ministry’s Outlook Regional Office or your local irrigation dealership.