East Texas Ag News: Water absorbs in lawns with soak and cycle method

Irrigation system on lawn at the Arboretum (Source: WECT)
Irrigation system on lawn at the Arboretum (Source: WECT)(wect)
Published: Jul. 17, 2020 at 4:37 PM CDT
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ANGELINA COUNTY, Texas (KLTV) -Last week I talked about the wonders of drip irrigation, mulch, and watering deeply with less frequency. This works best for shrubs and flower beds. But the lawn doesn’t get watered with drip irrigation.

So let’s talk about a relatively new irrigation strategy when you use the sprinkler on your lawns: the soak and cycle method.

You’ve seen it happen countless times; some well-meaning sprinkler system has excess water running out of the landscape, and down the street into the storm drain. It’s a waste of our best water and an unneeded expense to the homeowner.

What’s happening is that water isn’t being absorbed into the soil as fast as it is applied.

Our soils in Angelina County are typically a good loam over clay. In the south end, we have that grey clay, locally known as “post-oaky” clay. On the north end, red clay is the norm. I swear I have both types on my farm in Clawson, just north of Lufkin.

But it is that heavy, compacted clay soil that has a very slow infiltration rate. How much the soil can absorb depends on the type, slope, and other factors. A flat area can take up more per hour while a slope will start to run off after a quarter of an inch is applied, with the rest of the water being wasted.

One of our local Master Gardeners, Vickie Boren, first told me about the wonders of the soak and cycle method after she attended a state training to become an irrigation specialist. Put simply, the soak and cycle method breaks up your typical sprinkler cycle into at least 2 different, concurrent sessions to fully allow water to reach deep into the soil.

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 lightly soak, allowing that water to move into the soil, and then lightly soak again, and maybe even once more, applying up to the 1 inch or so needed per week.

Far too often, people 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.

The first step is determining how much water your sprinklers apply? You have to know how much you are applying so you will know how long to run the sprinkler system.

To determine the flow rate of your sprinkler heads, set several rain gauges or straight sided cans in your lawn 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.

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 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 healthy while being efficient with water use. So this means that on a given day the same area may have irrigation run three or four times on the same zone to allow water to reach deep into the soil.

Sound difficult? It’s not. Let’s review the steps.

First, determine the flow rate of your sprinkler heads. How many inches of water do they put out per hour?

Second, carefully observe your lawn to see how long before it quits absorbing water. 15 minutes? 30 minutes?

Third, re-program your time clock to soak and cycle the zones. Remember, the same zone will be watered several times on the same day with just enough water to be absorbed.

Lastly, monitor the lawn for a few weeks and make adjustments based on the various conditions.

Soak and cycle may still be 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 your lawn will be better for it.

Give it a try, and stop those light, frequent applications that help create awful conditions that lead to disease and even death of great lawns.

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