Posts Tagged: irrigation scheduling
Time to Adjust Your Irrigation
Irrigation is not a ‘set and forget' thing. Your watering schedule should be adjusted each season (at least four times each year) as water needs in the landscape vary greatly from season to season. Seasonal adjustments allow us to adapt to changing weather conditions, plant growth patterns, and water availability. If your irrigation system isn't adjusted with the seasons, your plants can suffer from overwatering in the winter or underwatering in the summer.
As seasons change through the year, your plants' needs will change, too. For example, a 15-foot wide Chinese pistache tree (Pistacia chinensis) growing in Concord needs 52 gallons of water each week in July, 24 gallons per week in October, and only 8 gallons each week in January. Adjusting irrigation according to the season can decrease water use by half and your plants will be healthier.
You can calculate how much water your landscape should have for best growth. Look up the water needs of your plants in this database: https://ccuh.ucdavis.edu/wucols-db. Determine how much water is needed for each of your plants throughout the year here: https://puddle-stompers.com/waterwonk/how-much/index.php
Even knowing what your plants ‘should' need, it's best to test your soil occasionally to make sure the water you apply is getting to the right place. To test the depth of your watering, use a soil sampling tube or a small trowel to dig down 6–8 inches deep and observe the moisture level at the bottom of the hole. Get your hands dirty and learn what your soil feels like with varying moisture levels.
There can be substantial water waste when automatic watering systems are left to run on their own. Some systems come with a rain sensor function that will automatically turn off the system when it rains and others are smart controllers that adjust the schedule based on environmental factors. It might be time to upgrade your controller to take advantage of these benefits.
Some additional reminders for good irrigation practices:
Apply the right amount of water
Overwatering is more common than underwatering and can lead to more disease problems.
Water plants deeply and infrequently
The entire root zone should receive water, but let the soil dry partially in between to reduce the chance of root rot and other diseases.
Water early in the morning
Cooler temperatures and less wind will reduce evaporation, especially if using sprinklers or above-ground systems.
Avoid runoff
This happens often in clay soil and the water is simply wasted. Cycle the irrigation giving enough time for each cycle to be absorbed.
Regularly maintain your irrigation system
Check for leaks or damaged parts that could be wasting water and preventing water from getting to the right place.
Apply mulch
A 2- to 4-inch layer will reduce evaporation, minimize weed competition, and improve the soil.
See these links for more information on irrigation:
https://sonomamg.ucanr.edu/Drip_Irrigation/Drip_Irrigation_in_Different_Landscape_Situations/
https://sonomamg.ucanr.edu/Drip_Irrigation/
Help Desk of the UC Master Gardeners of Contra Costa County
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CropManage Hands-on Workshop, San Martin CA, March 29, 2023
CropManage Hands-on Workshop
Bringing Irrigation and Nutrient Management Decision-Support to the Field
Date: Wednesday, March 29th, 2023
9:30 am – 2:30 pm
Location: Animal Services Center
Address: 12425 Monterey Road, San Martin, CA 95046
- Learn how to use CropManage to support irrigation and nutrient management decisions and record-keeping for your crops
- Learn about the latest updates to CropManage
- Learn how CropManage can assist with reporting requirements for Ag Order 4.0
CropManageis a free online decision-support tool for water and nutrient management of vegetables, berry, agronomic, and tree crops. Based on in-depth research and field studies conducted by the University of California Cooperative Extension, CropManage provides real-time recommendations for efficient and timely irrigation and fertilization applications while maintaining or improving overall yield.
At this free workshop, we will provide hands-on training so that you can learn to use the newest version of CropManage. Crops currently supported include many vegetables (carrots, cabbage, celery, broccoli, lettuce, tomato, spinach, etc.), berry crops (raspberry and strawberry), tree crops (almond, walnut, pistachio, prunes, and pear), and agronomic crops (alfalfa and corn). CropManage is also available in Spanish.
Who should participate? Growers, farm managers, other farm staff, crop advisors, consultants, and technical service providers are welcome. The workshop is for both new and current CropManage users. Spanish translation will be available. Lunch will be provided.
What to bring? This is a participatory workshop. Please bring a tablet or laptop computer so that you can follow along and participate in the exercises. Each participant will need a user account for CropManage. Please set up a free user account at https://cropmanage.ucanr.edu/ before the workshop. Please arrive early to set up your laptop or tablet computer on the wifi and get logged on to CropManage.
Registration is free: Please register here
by March 28th, 2023. Seats are limited to the first 40 registrants.
Agenda
9:30 – 10:00 am |
Registration and computer set-up |
10:00 – 10:30 am |
Introduction |
10:30 – 12:00 pm |
Getting started with CropManage |
12:00 to 12:30 pm |
Lunch break |
12:30 – 1:15 pm |
Using CropManage for decision support and record-keeping |
1:15 – 2:00 pm |
Group exercise |
2:00 – 2:30 pm |
Discussion / Q&A / wrap up |
CropManage Hands on Workshop Santa Clara County 2023 English
2023 CropManage Hands on Workshop Santa Clara County Spanish
UCCE Partners with Department of Water Resources to Post Timely Crop Water Use Estimates To Aid Growers With Irrigation Scheduling
Scheduling irrigation events based on crop use allows growers to meet the water demands of crop...
Figure Farm Bureau 5 14 2022
CropManage Hands on Workshop May 10th, 2022
Date: Tuesday, May 10th, 2022 1pm – 5pmLocation: Watsonville Public Library 275...
Irrigation strategies for avoiding heat damage to cool season vegetables
Currently, we are experiencing a prolonged heatwave on the central coast. Heatwaves have become a recurring phenomenon in recent years, especially in late summer. With thousands of acres of cool season vegetables in the ground, irrigation will be critical for keeping crops cool and for supplying enough moisture to meet their water needs.
Crops can be kept cool by maximizing evapotranspiration (ET). As liquid water vaporizes heat is lost from the surfaces of leaves and soil and from the surrounding air, which cools the temperature of the crop. Under water stress leaf stomates close during the hottest period of the day (11 am to 4 pm) and the temperature of the plant tissue can rise above the temperature of the surrounding air. If the temperature becomes too great leaves and other plant parts may become scorched (Figure 1).
Figure 1. Heat damage in broccoli
Since most ranches have a limited number of wells and personnel to irrigate, it is challenging to assure that each field has adequate soil moisture to prevent plants from overheating. A good strategy is to irrigate just enough to refill the soil profile to the rooting depth of the crop.
To prioritize which fields to irrigate one should consider the water holding capacity and existing level of moisture of the soil, as well as rooting depth and developmental stage of the crop. For example, a lettuce crop near maturity with a high ET demand, growing on a sandy textured soil that feels dry, should probably be irrigated soon. A young lettuce crop with a low ET demand, growing on silt loam soil that still feels moist, likely can be irrigated later without suffering heat damage.
Another consideration for prioritizing which fields to irrigate are recent field operations. A recently transplanted vegetable field may need to be irrigated first but may not need a long irrigation to re-saturate the soil around the roots. A crop that was recently cultivated may have pruned roots, and therefore may need water soon to prevent wilting under these hot conditions.
Table 1 estimates how much moisture is available to a vegetable crop between saturation and moderately dry or dry conditions for different soil textures. This table can be a guide for how much water should be applied to re-saturate the soil. For example, applying 0.42 inches per foot of rooting depth will bring a moderately dry silty clay soil back to saturation. Applying more than this amount of water will likely over-saturate the root zone.
Table 1. Estimated plant-available moisture for different textured soils.
Also, estimating the cumulative crop ET since the last irrigation can guide how long to irrigate. Reference ET values between south Salinas and Soledad during this hot spell have been as high as 0.27 inches per day. If the crop has a full canopy, 0.25 to 0.3 inches for each day since the last irrigation would be a good rule of thumb for how much water to apply as long as the total does not exceed the water holding capacity of the soil.
Lastly, one needs to convert the amount of water to apply to an irrigation run-time. To make this calculation one needs to know the application rate of the irrigation system. For impact sprinklers, the application rate can be estimated using Tables 2-4. Note that pressure and nozzle size have a significant effect on application rate. For drip, the irrigation time will depend on the tape discharge rate and pressure, as well as the spacing of drip lines. Assuming that the drip system is operated at the pressure recommended by the manufacturer (usually 8 to 10 psi) one can use Table 5 to approximate the application rate. For example, for one drip line of medium flow tape (0.45 gpm/100 ft) on 40- inch wide beds the application rate of the drip system is 0.13 inches per hour. If there are several drip lines per bed then multiply the application rate in the table by the number of drip lines.
The appropriate run-time can be estimated by dividing the amount of water to apply by the application rate of the irrigation system. For example, to apply 0.6 inches of water to a field with drip using medium flow tape the water would need to run for 4.6 hours:
Hours to operate the irrigation system = 0.6 inches of water/0.13 inches per hour = 4.6 hours
Summary
Irrigating the right amount of time to bring the soil back to saturation will maximize crop ET during these hot days, and hopefully prevent any heat damage to crops. Also, consider visiting the CropManage website (cropmanage.ucanr.edu) for further guidance on scheduling irrigations. This online tool can assist growers in quickly estimating how much water to apply to meet crop water needs.
Table 2. Sprinkler application rate for varying pressures and nozzle diameters for a solid set spacing of 30 × 30 feet (Rainbird 20JH).
Table 3. Sprinkler application rate for varying pressures and nozzle diameters for a solid set spacing of 30 × 33.3 feet (Rainbird 20JH).
Table 4. Sprinkler application rate for varying pressures and nozzle diameters for a solid set spacing of 30 × 40 feet (Rainbird 20JH).
Table 5. Drip application rates for varying bed widths and tape flow rates estimated for 1 drip line per bed. Multiply the rate in the table by the number of drip lines per bed to determine the actual application rate. (For 3 drip lines on an 80-inch bed multiply by 3)