Soak and Cycle Lawn Irrigation — Do You Soak and Cycle?

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Knowing how to water your lawn during the stressful summer conditions is difficult for just about everyone. What if I told you I had the magic bullet for knowing how to water so that you have a healthy lawn while maximizing the water resource efficiently? Does that sound intriguing? Well it is, but I will be honest and up front. It will require some effort on your part to make it work. But once you’ve figured it out it’s easy as pie.

The soak and cycle method takes the guesswork out of lawn watering, ending the debate over light, frequent or deep watering. The soak and cycle method closest mimics natural rainfall by soaking the soil and then allowing the soil to slightly dry. This combination develops a soil condition that encourages strong roots for a more drought tolerant and disease free lawn.

What is soak and cycle?
The soak and cycle method works best for in-ground sprinkler systems, but for hose draggers like me it has merit. The theory behind the method is to soak the soil to a depth of 6 to 8 inches, which is where grass roots should grow to develop a nice lawn. The cycle phase refers to the fact that water will not be applied faster than the soil can uptake. So first we soak, allowing that water to move into the soil, and then soak again and maybe even again, applying up to the 1 inch or so needed per week to remain green in summer.

How much water can local soils absorb?
Our local heavy, compacted clay soils have a very slow infiltration rate. In fact, many soils cannot absorb more than two-tenths of an inch of water in one hour. How much the soil can absorb depends on type, slope and other factors. A flat area can take up more per hour while a slope will start to run off after two-tenths is applied, with the rest of the water being wasted. Simply stated, if you add water faster than the soil can absorb it it is wasted!

How much water does your system apply?
Okay, here is the tricky part; do you know how much water your sprinkler heads apply? If you don’t know how much you are applying then how do you know how long to run the sprinkler system? Or, do you just water and keep the grass green and alive, which is probably wasting water and increasing disease and root problems.

To determine the flow rate of your sprinkler heads set several rain gauges or straight sided cans in the pattern and measure the amount applied in 30 minutes or an hour. This rate of application combined with the infiltration rate will determine how long to run the system in each zone.

Soak
The soak part then applies that amount of water to that zone. For example, if you determine your lawn can take up about two or three-tenths of an inch of water before running off, then apply that rate of water to the area and turn off the system on that zone. You are now ready to cycle

Cycle
Cycle then means to water another zone and allow that water that was just applied to soak into the soil. Then you go back to the first zone and soak it again. This may require several soaking and rest periods to apply the needed 1 inch of water per week to keep the lawn spring green while being more efficient with the water use. So this means that on a given day the same area may have the system run three or four times on the same spot or zone.

How often do you water?
Using soak and cycle, the area, or zone, is not watered again until the soils dry and the grass starts to wilt. In the hot Kansas City summer the lawn loses about one-third of an inch of water each day. So based on the cycle method, once the soil is soaked it will probably take about three to four days to dry down to the point of needing to be watered again. This means that your system still may run every couple of days, but not the entire area, just the ones that are ready for the next soak and cycle pattern.

Soak and cycle ends light frequent applications
Traditionally people have run their systems over the entire lawn every couple of days, or three or four times a week, and they probably have no idea of how much water is applied. This method concentrates all the water in the upper few inches of the soil, developing a shallow root system and disease prone plant. With Soak and Cycle, each zone is probably soaked about every three to five days, depending on the area’s factors such as sun and shade, slope, soil type and several other factors.
Sound difficult? It’s not.

I know this is a lot to absorb, no pun intended but it only requires you to do three simple steps.

1. Determine the flow rate of your sprinkler heads. In fact, you should already know that.
2. Re-program your time clock to soak and cycle the zones. Remember, the same zone will be watered several times on the same day. The system still might run just about every day but on different areas.
3. Monitor the lawn for a few weeks and make adjustments based on the various conditions.

Soak and cycle is a new concept for lawn watering but once it is figured out it takes the guesswork out of the equation, as you know how much water is being applied, the rate in which the soil can absorb, and it allows for healthy roots. Give it a try, and stop those light, frequent applications that helped created the horrid conditions that lead to last year’s collapse in the heat of summer.

Have questions? The Garden Hotline is staffed by trained EMG volunteers and Extension staff who will assist you with questions.

Phone: (913) 715-7050

Email: garden.help@jocogov.org