As we come to the close of the 2024 growing season there is time to think about how to improve in the upcoming year.  Please consider implementing some of these tips on irrigation management as you prepare for the 2025 season.  Our  staff is happy to assist you with any water or nutrient management challenges you may have.  Just give us a call (831-759-7377) or send an email (mdcahn@ucanr.edu).  Happy Holidays!

1. Test your water and soil for salts. The quality of your water can be as important as the quantity. Many vegetables are sensitive to salinity, so you want to be sure that the water applied to your crop has a low level salts. Also, because salts from irrigation water accumulate near the crop roots over time, one needs to test the salinity of the soil periodically to determine if leaching is needed. The main constituents to test for in a saturated paste extract of a soil sample are pH, bulk salinity (TDS or electrical conductivity), Ca, Mg, Na, Cl, SO₄, NO₃, HCO₃, and B. Test the same constituents for water but also add Fe and Mn. Seek out advice from an experienced agronomist/soil scientist/ or crop consultant who can help you interpret the test results.

2. Evaluate the application uniformity of your irrigation system. The more uniform that your irrigation system distributes water to your crop, the less water is needed to achieve good yields and quality. Using 30 equal sized cups and a stop watch, you can evaluate the distribution uniformity of your sprinkler or drip system. Alternatively, consider hiring an irrigation consultant to conduct a more intensive evaluation. 

Fig. 1. Evaluating the uniformity of an irrigation system can determine if water is being applied efficiently

3. Evaluate the design and operation of your irrigation system. Many problems with irrigation systems are caused either by a poor design, lack of maintenance, or because they are not operated correctly. An experienced irrigation consultant should be able to narrow down to the main issues that limit the performance of your irrigation system, and recommend the most cost effective solutions.

Fig. 2. An irrigation consultant can evaluate the design and operation of your irrigation system and often pin-point problems that limit performance.

5. Monitor pressure of the irrigation system. Getting the best performance from your drip and sprinkler systems depends on operating them at the right pressure. Variation in pressure will vary the flow and uniformity of applied water. Use high quality gauges to monitor pressure at different locations in the field, including at the closest and furthest points from the water source or irrigation valve.  

Fig. 3. Monitoring pressure ensures that irrigation systems are operating optimally

 

6. Measure how much water you apply. It is difficult to save water if you do not know how much you are applying to your crops. Using a flowmeter and keeping records of the amount of water applied for each crop can help you determine if the amount of water you are applying is matching crop needs. 

Fig. 4 Flowmeters are very useful tools for irrigation scheduling. They can be used to monitor how much water is applied to a crop.

7. Use weather information and soil moisture to guide irrigation scheduling. The closer that you can match the irrigations with the needs of your crop, the more efficient your water use will be. Irrigation scheduling is the combination of deciding when and how much water to apply. Water needs of the crop change during the season as weather conditions vary and the crop matures. Monitoring soil moisture can help you decide when to irrigate and using evapotranspiration data from weather stations can help with estimating how much water to apply.

Fig. 5. Monitoring soil moisture with a tensiometer can help decide when to irrigate vegetable and berry crops.

Fig. 6. Weather stations which collect evapotranspiration data can be used to estimate how much water a crop requires

8. Conduct regular maintenance of the irrigation system. Just like your car needs periodic servicing, an irrigation system need regular maintenance. Leaks in drip tape, pipe, and layflat need to be patched. Drip lines and filters need to be flushed. Sprinkler heads, nozzles, and gaskets wear out and need to be replaced. Develop a schedule for irrigation system maintenance.

Fig. 7. Regularly schedule maintenance to fix leaks, and head off other problems that limit the performance of an irrigation system.

9. Train your irrigators. A well trained irrigator can help solve a lot of water management problems on your farm. An irrigator's job goes beyond moving pipe and drip tape. They should have a good, basic understanding of how the irrigation system operates, be able to keep accurate records, and understand how to make routine measurements to assure the irrigation system is operating correctly. They also may need training on the operation of new equipment and maintenance procedures. Providing regular training opportunities so that irrigators can increase their skill set will make them more valuable to your farming operation.

Fig. 8. Providing training for your irrigators will improve their skills in the field.

10. Infiltrate winter precipitation for salinity management. The best water for leaching salts from your vegetable fields is free, and comes from the sky. Letting storm water run-off your fallow fields is a lost opportunity to remove salts. Using cover crops, tillage, or adding soil amendments can increase infiltration of winter rains and will help control potential salinity problems.

Fig. 9. Low biomass cover crops planted in the fall can greatly reduce runoff and increase infiltration from storm events during the winter.