"Water, rest, water, save"

Cycle and Soak is a useful RainMachine program irrigation feature that helps prevent runoff and allow more time for different types of soil to absorb the water from your sprinklers irrigation.

What is a program cycle?

Program cycle: represents one sequence of watering that goes through all the program zones. The total program watering time (all zones watering times combined) is split equally in shorter duration by the number of the cycles.

What is soak time?

Soak time is a pause in between program cycles needed for the soil better absorb a certain quantity of water. It is very important to know the soil type for your zones and set it properly under the Advanced Zone Settings screen. The type of soil you have ― sand, clay, or loam ― influences how fast water penetrates before running off, how often plants will need to be watered, and how much water you'll need to apply with each irrigation. 

What is the soak minimum recommended time?

We recommend that the minimum soak time to be at least equal the zone watering duration, or no less than 30 minutes. 

How to set Cycle and Soak?

Currently there are two ways how to set this option under Program edit screen:

• Custom (manually set the number of cycles and the soak time in between)
• Auto (let the RainMachine automatically calculates this based on your advanced zones settings)
  
  

In our example we will use this advanced zone settings for our 4 program watering zones:

Custom Cycle And Soak


Example: A program set to run 4 zones with minimum soak duration 30 minutes to allow the soil to absorb the water and each zone set to irrigate for a total of 12 minutes, split the program in 3 cycles and 18 minutes soak time using the Custom "Cycle and Soak" option.

Note: This 18 minutes results from: Zone 1 watered 4 minutes and then it waits for the Zone 2, Zone 3 and Zone 4 to finish their 4 minutes from Cycle #1. That's 12 minutes without being watered plus another 18 minutes of Soak time equal the minimum 30 minutes. The same applies for the other 3 zones left from this program.

We used the same vegetation type and the same sun exposure for all zones, but different types of soil, sprinkler heads and slope (see the table above).

The program breakdown from start to finish will look like this:

Cycle #1

• First program cycle will run each zone for 4 minutes with a total run time of 16 minutes.

Soak time: 18 minutes.

Cycle #2

• Second program cycle will run each zone for 4 minutes with a total run time of 16 minutes.

Soak time: 18 minutes

Cycle #3

• Third program cycle will run each zone for 4 minutes with a total run time of 16 minutes.

End of program. 

Total: 48 minutes (3 cycles) + 36 minutes (soak time) = 84 minutes.

Note: At the program scheduled start time this total program runtime can vary in length depending on the weather conditions and the restrictions available that affects zones watering times. If you manually start the program the zones watering times will not be affected in any way.

During the soak time there is no watering activity on any of the zones. This is essentially dead time increasing the length of the program. Keep this in mind when planning your schedule!

Automatic Cycle and Soak

Let's choose the same program to run 4 zones for 12 minutes each, but right now the "Cycle and Soak" option is set to Auto.

Watering activities breakdown:

How it's done?

There is no pattern of how many cycles and soak times will be generated, their number is variable and the reason is that RainMachine algorithm uses this formula to auto generate them:

• Maximum Run Time: The maximum allowed watering time in one cycle before runoff occurs, suggested by EPA WaterSense.
• Allowed Surface Accumulation: The maximum height of water that is allowed to accumulate over the soil surface before runoff occurs.
• Precipitation Rate: The quantitative precipitation that the sprinkler head can deposit per hour. This value can be calculated either by a catch cup test or by zone water meter flow and area.
• Intake Rate: The rate at which soil is able to absorb rainfall or irrigation, if this value is below the sprinkler head precipitation rate, RainMachine will automatically split the watering in cycles to prevent runoff.

The default soil type intake rates and sprinkler head types precipitation rates the RainMachine algorithm take in consideration when automatically calculates the number of cycles and soak times are:

Note: Automatic Cycle and Soak program feature is already available with the new firmware update v.4.0.844 releases on Dec 20, 2016 for our RainMachine Mini-8 devices.

Conclusion

Custom Cycle and Soak - using this mode you can specify the number of cycles and the amount of soak time. This mode always divides the watering time for a zone by the numbers of cycles specified and RainMachine will always wait the specified soak time between the cycles. This mode is used for users that have their own cycle & soak needs.

Automatic Cycle and Soak - using this mode RainMachine will automatically calculate the number of cycles and soak times needed using EPA WaterSense algorithm. The number of cycles and soak time depend on zone soil, sprinkler head and slope properties and can vary from zone to zone. In EPA WaterSense terminology this is called the *maximum run time* and define how many seconds a zone can be watered before runoff occur. The soak time between cycles is the maximum of this value for the zones in a cycle. As a consequence some zones can get more cycles than others and soak time will only be added between cycles if required.

 
Resources

• Water Smart Landscapes, by EPA WaterSense (Adobe PDF)
• Cycle and Soak Method, by Texas A&M AgriLife Research and Extension Center at Dallas (Adobe PDF)
• Cycle and Soak Watering, by Southern Nevada Water Authority (SNWA)
• Cycle and soak watering method, by Colorado Spring Utilities (YouTube video)