By Joel Peru, PAg, CCA, Irrigation Agrologist
With intensive irrigation, producers are able to apply water to their crops when – and 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.
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 efficiently. In order to schedule irrigation successfully, there are four parts of information that are key to know: 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 seven mm/day during pod fill but will only use two mm/day during the rosette stage. Another crop such as peas will use a maximum of six mm/day during pod development and will not use more than two 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 next irrigation can be estimated. The three methods include feel method, moisture monitoring equipment method, and computer model and weather data information method. Irrigation scheduling is a cheap practice that often only requires a couple rain gauges, a Dutch auger, and knowledge of your crop and soil properties.
Remote techniques that transmit reliable data from the moisture measuring instrument in the field to hand-held electronic devices are currently available. Irrigators support their on-site field moisture measurement with rainfall data and use a check-book approach or a computer modeling program to predict crop water use. A significant number of new tools have been developed to automate the process and improve remote communication between in-field monitoring devices and the irrigator. Remote moisture sensing will become more common as the technology improves and becomes more cost effective, as it can save a producer time and money by reducing the need to check fields as frequently.
The Irrigation Scheduling Manual has been recently updated by the Ministry of Agriculture. ICDC provides weekly crop water use updates throughout the growing season on their Twitter page.
More information and assistance can be found by contacting an Irrigation Agrologist or reading the Irrigation Scheduling Manual. You can reach an Irrigation Agrologist at 306-867-5500.