Microsprinkler irrigation in almond Almond Board of California
Microsprinkler irrigation in almond.

Post-harvest is prime time for irrigation system maintenance

Good irrigation management begins by understanding overall system performance, including comparing system benchmarks against current operating performance

By late October or early November, almond growers should finish their post-harvest nutrient applications and focus on putting the irrigation system to bed for the winter.

Efficiency is key to ensure all post-harvest irrigation tactics are complete before the end of the season. When reviewing your post-harvest nutrition budget with your agronomist or pest control advisor (PCA), talk with them about an irrigation evaluation if not done previously. This test helps identify easy fixes that you can do now to improve the 2018 season.

Remember that good irrigation management begins by understanding overall system performance, including comparing system benchmarks against current operating performance.

Follow this post-harvest irrigation checklist to get a head start on next year’s crop.

1. Clean and flush irrigation lines - Before taking performance measurements, flush out the irrigation system - including filters, mainlines, and submains - to ensure it’s working optimally.

2. Examine nozzles and wetting pattern -Examine emission devices (drip emitters, sprinklers or microsprinklers) for wear, including mineral and scale build up. Check for uniform wetting patterns.

3. Install and/or check flow meters and moisture sensors - Whether you are using drip, microsprinklers, or sprinklers, a main impact on system performance is the application rate measured in gallons per hour.

Flow meters are essential even if you already monitor run time and calculate applied water based upon your system’s design.

The emission devices within your irrigation system are designed with a Coefficient of Variation (CV). This accounts for the accepted variance between each emission device. Depending on the manufacturer and emission device type, the CV will vary as much as a few tenths of a gallon. This amount doesn’t seem like much but when you do the math it adds up fast, especially if the system has poor distribution uniformity. Flow meter use can eliminate variability, indicating how much water was applied to the orchard. After all, our No. 1 applied nutrient is water and it is very difficult to manage what you don't measure.

Winter is also a great time to install soil moisture sensors to give the sensor time to equalize to the soil, plus gives you time to understand what the data means come spring. For existing soil moisture sensors, inspect for damage resulting from harvest or normal wear and tear.

4. Monitor pressure - Pressure measurements are relatively easy to obtain in irrigation systems, but techniques can vary for sprinkler, microsprinklers, and drip. Refer to the Almond Irrigation Improvement Continuum 1.0 manual for detailed directions.

You can quickly gain the pressure of your irrigation system by using a pressure gauge fitted with a pitot tube - a hollow brass tube available at an irrigation equipment supplier. 

5. Ask the experts: Distribution uniformity - Determining the distribution uniformity of the irrigation system can be time consuming, and accuracy is important. I highly recommend consulting a professional irrigation system evaluator for those new to this process.

Distribution uniformity is widely overlooked in irrigation system evaluation, yet it has the single biggest impact on water use efficiency. It’s well worth consulting an expert.

6. Determine if winter irrigation or leaching is required - Regionally, growers use winter irrigation to replenish water in the soil profile. It’s also a good time to determine if winter leaching is required to prevent the build-up of salts in the root zone before spring. Excess salinity endangers crop growth.

All irrigation water contains dissolved mineral salts, confirmed by a lab analysis of water samples. If you think the water quality has changed since the last sample, conduct an updated sample before leaching. As you review the water and soil lab results with your PCA or agronomist, determine if dormant leaching is necessary.

For more information on managing salinity based upon soil type, refer to the Salinity Management link on UC Cooperative Extension’s Almond Doctor website, www.TheAlmondDoctor.com.

The Almond Board of California is committed to providing almond growers with water efficient irrigation management and scheduling tools. I’m available for irrigation resources and insights specific to your farm. Contact me at [email protected] or (209) 604-3727.

Beyond the orchard, I look forward to seeing you at The Almond Conference Dec. 5 – 7 at the Sacramento Convention Center. I invite you to attend my seminar “Tools for Better Irrigation” on Dec.6. I hope to see you there!

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