Summary
Want to make a quick edit to watering durations? Flexible Daily schedules automatically select durations for your zones based on the attributes that have been selected. To edit the durations recommended, go to the Schedule tab, select the schedule you want to edit, and select Watering Duration.
After clicking on Watering Durations, you can edit the durations in minute-by-minute increments. These adjustments can be made to any, some, or all zones.
WARNING
It is not recommended to adjust watering duration here as this will override the precalculated duration based on your input zone settings and impact soil moisture tracking. See How can I adjust Flexible Daily Schedules?
How can I adjust Flexible Daily Schedules?
If you really want to understand how everything fits together and which dial does what, the following explains how each zone attribute affects the duration and interval of a zone:
- Vegetation type = crop coefficient/plant factor + root zone depth
- Soil type = water holding capacity (AWC)
- Shade setting = microclimate factor
- Nozzle type = precipitation rate + distribution uniformity
- Allowed depletion = defaults to 50% (can be edited +/-)
If you don't have time to read the whole article, below is a summary of adjustments and what they affect:
| Zone Attribute | Run time | Frequency |
| Crop coefficient |
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| Soil available water capacity (AWC) |
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| Crop root zone depth (RZD) |
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| Sun/Shade setting |
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| Management allowed depletion (MAD) |
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| Nozzle type |
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Crop Coefficient
The best lever for adjusting watering frequency. Each crop type has a coefficient. Crop coefficients are properties of plants used in predicting evapotranspiration (ET). The coefficient is the ratio of ET observed for the crop. If ET is our zone checkbook debit, crop coefficient will offset ET slightly and not remove as much from our account.
Example: ET for the day is .2 inches. Crop coefficient for cool-season grass is 80%. The debit for the day is .16 inches (.2 x .80).
Increasing crop coefficient increases watering frequency, decreasing crop coefficient decreases watering frequency.
Recommend moving the crop coefficient lever +/- 10% increments and see if that gets watering to the correct cadence. Crop coefficient can be modified from Zone Menu > Advanced Settings > Crop Coefficient.
Soil/Available Water Capacity (AWC)
Soil type affects the available water capacity (AWC). AWC is the amount of water that a soil can store that is available for use by plants.
We have chosen industry-standard AWC default values:
Increasing AWC will increase the irrigation amount needed, which will increase the run time but decrease watering frequency. The opposite also applies. Decreasing AWC will decrease the irrigation amount needed, which will decrease the run time but increase watering frequency.
AWC can be modified from Zone Menu > Advanced Settings > AVAILABLE WATER
Root Zone Depth (RZD)
Each crop has a default root zone depth (RZD) as well as a crop coefficient. RZD is used to calculate the amount of irrigation applied, which obviously affects the run time. The longer the roots, the greater the irrigation amount, the greater the run time.
We have chosen industry-standard RZD default values:
As you can see for crops like trees and shrubs with much deeper roots, the watering duration will be longer, but the frequency of watering will be much less. Increasing RZD will increase the irrigation amount needed, which will increase the run time but decrease watering frequency. The opposite also applies. Decreasing RZD will decrease the irrigation amount needed, which will decrease the run time but increase watering frequency.
RZD can be modified by going to the Zones tab, selecting the zone you want to edit, choosing Advanced, and scrolling to Root Depth.
Sun/Shade Setting
Sun exposure is used as a ratio of crop coefficient, which is used as a ratio of ET. When a zone receives less sun, this will decrease its overall ET value, which will in turn decrease watering frequency.
Sun exposure can be modified in the Zone settings.
Management Allowed Depletion (MAD)
This value, expressed in percent, is the portion of water in the root zone that plants can utilize before experiencing stress. At some point (just after the management allowed depletion level), the plant becomes stressed. As the soils become even drier, the plant will eventually reach its permanent wilting point. We default to 50% MAD for each zone. Increasing the MAD percentage will decrease the irrigation amount needed, which will decrease the run time but increase watering frequency. The opposite also applies. Decreasing the MAD percentage will increase the irrigation amount needed, which will increase the run time but decrease watering frequency.
MAD can be modified by going to the Zones tab, selecting the zone you want to edit, choosing Advanced, and scrolling to Allowed Depletion.
Nozzle
Choosing the correct spray head (or accurately customizing the precipitation rate in your zone's advanced settings) is one of the most important factors in determining a zone run time. Nozzle precipitation in/hr is one of the factors used in calculating watering duration. A higher precipitation rate will lower the overall run time and vice versa. To learn more about precipitation rates, please see this support article.
Nozzle type can be modified from Zone settings.
Real-time Flex Schedule Manipulation
One of the great things about Flex Schedules is that they are flexible. Feel free to modify zone settings and go back to the calendar view or flex schedule to dynamically see run times and/or frequency change as you modify characteristics.
Further Reading
If you need more, and are hungry for the science behind this, a lot of the concepts we've used are from the article Irrigation Scheduling: The Water Balance Approach
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