| | Water-efficient Equipment | Irrigation Applications
Environmental considerations in irrigation farming include ensuring the efficient use of water and preventing soil salinity and associated drainage problems that can be caused by canal seepage, poor water management and poor irrigation practices.
On a farm level, irrigation water management involves the determination and control of the rate, amount and timing of irrigation water in a planned and efficient manner. The purpose of irrigation management is to effectively use the available water supply in managing and controlling the moisture environment of crops to promote the desired crop response, minimize soil erosion and protect water quality. Proper irrigation management requires a good understanding of soil, crop and climatic properties that affect soil water movement and storage, and crop water use. This knowledge leads to the development of workable and efficient irrigation schedules.
Water-efficient Equipment
Irrigation systems have become more efficient in recent decades, reducing water losses through deep percolation, runoff, evaporation and wind drift. Some of these advances have also improved energy efficiencies.
Irrigation systems are more efficient reducing water losses through deep percolation, runoff, evaporation and wind drift.
Courtesy of ARD - Irrigation Branch
The most water-efficient systems are pivot or lineal move systems with drop tubes and low pressure spray nozzles that are designed to meet crop and soil requirements. Drip systems or other similar systems apply water to the plant rooting area only. Efficiencies of surface irrigation systems have been improved through use of gated pipe, surge valves and siphon tubes and other measures to reduce water use and runoff.
Beneficial management practices for irrigation equipment include:
- Choose a water-efficient system, or upgrade your current system to reduce water losses, energy costs and environmental costs. Water losses result in increased runoff and increased movement of nutrients, sediments and other substances into water sources, harming water quality and aquatic habitats. As well, nutrient losses represent wasted input costs.
- Ensure your irrigation system is properly designed and sized for your operation.
- Conduct regular maintenance checks, and make needed repairs such as stopping leaks and replacing worn nozzles.
- Investigate options for upgrading your system about every five to 10 years.
Within an irrigation district, canal maintenance is the responsibility of that irrigation district. With assistance from the Alberta and Canadian governments, Alberta's Irrigation Districts are replacing, relocating, and lining canals on an ongoing basis to eliminate seepage and improve water delivery efficiency.
Irrigation Applications
Appropriate timing and amounts of irrigation water improve crop yields and decrease the amount of water lost to percolation and runoff. Reducing water loss improves water efficiency, minimizes the risk of nutrient losses, soil salinity, drainage problems, and keeps operating costs down.
Beneficial management practices for irrigation applications include:
- Select crops suited to your local soil and climate, choose healthy seed, and fertilize to meet the crop's needs.
- Know how much plant-available water your soil can hold at field capacity and then irrigate to 90% of the capacity, while leaving 10% for possible rainfall. Use the texture-based guide in Table 3.6.
- Learn about the water needs of your specific crop variety. Water requirements depend on the crop type, variety and stage of growth, target yield and crop management.
- Use irrigation scheduling to ensure that soil moisture is kept sufficiently high to promote active plant growth, while avoiding unnecessary water applications.
- To prevent runoff , ensure that the irrigation application rate is equal to or less than the soil's infiltration rate (Table 3.6).
- Fertilize according to the soil test recommendations to ensure that soil fertility does not limit the crop's ability to use water efficiently.
- Use computer software and weather data to continuously adjust your irrigation schedule.
- Monitor soil moisture on a weekly basis. Monitoring options include soil moisture sensors, crop water use models, direct measurement of crop use, or the feel method.
- Monitor and record water application rates and volumes.
- Avoid irrigating soon after pesticide or fertilizer applications. Check product label for details.
Land must be assessed as to its suitability for irrigation prior to irrigation development within or outside of an irrigation district. Land classification for irrigation is required: a) as input to an agriculture feasibility report to obtain a water licence for irrigation development outside an irrigation district; and b) to obtain a water right for irrigation development within an irrigation district. Only land classified as suitable for irrigation can be granted a licence or water right for irrigation in Alberta. The economic risk and risk of on-site and off-site environmental impacts are reduced by irrigating only those lands that are suited to irrigation.
Table 3.6 Plant-available water and infiltration rate based on soil texture
| Soil Texture | Plant-available Moisture in 1-M Root Zone | Basic Infiltration Rate When Soil is Saturated |
 | (mm) | (in) | (mm/h) |
| Loamy Sand | 112 | 4.4 | 26 - 60 |
| Sandy Loam | 140 | 5.5 | 25.6 |
| Loam | 180 | 7 | 6.8 |
| Sandy Clay Loam | 152 | 6 | 4.3 |
| Silt Loam | 200 | 8 | 13.2 |
| Clay Loam | 200 | 8 | 2.3 |
| Silty Clay Loam | 220 | 8.7 | 1.5 |
| Sandy Clay | 172 | 6.8 | 1.2 |
| Silty Clay | 212 | 8.3 | 1 |
| Clay | 192 | 7.6 | 0.6 |
Adapted from: Alberta Agriculture, Food and Rural Development. 2000. Procedures Manual for the Classification of Land for Irrigation in Alberta. Alberta Agriculture and Rural Development, Lethbridge, Alberta.
- For more information, visit your ARD irrigation specialist for individual irrigation management recommendations, the Alberta Irrigation Management Model software, and publications. ARD's website has irrigation information, climate and weather data, and a list of trained land classification consultants.
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