Using An Irrigation System to Combat Drought

#fundamentals #scheduling May 16, 2024
Using An Irrigation System to Combat Drought

Your irrigation system can be your best way of combating drought without overusing water.  Droughts have become a major issue to the green & water industries. With inconsistent or reduced rainfall, some water systems have resorted to placing watering restrictions on their customers. How will you cope with the situation, continue to irrigate your landscape adequately, and protect your investment? How can we irrigate in a sensible manner without being damaging to the environment?
  
   Fluctuations in regional weather patterns have played a part in the overall disruption, but the rising water demands of urban populations have played an even larger part. Mismanagement of irrigation systems has had a detrimental effect on reservoir levels in some parts of the country. While proper irrigation can be a massive benefit to the environment, the proliferation of residential lawn sprinkler systems has led to much waste. This provides an opportunity for us to educate contractors and homeowners how to responsibly use their systems. Sometimes a drought can be a good thing, in that many people are forced into a realization that less water can adequately maintain their landscape.

   Most contractors are sure to have seen it, sprinkler systems set to run heavily every day, with rivers of wasted water running down the street. In fact, watering too frequently can be the root of an unhealthy landscape. Whereas some ornamentals or crop species prefer "wet feet" or a root system that's kept closer to saturation, most species including turfgrass prefer a regular wet/dry cycle. Soil that's kept saturated can prevent adequate oxygen from making it to the roots. Constantly providing water to a shallow root system doesn't provide motivation for the plants to develop more extensive roots. There are always some clients that we know we'll get mid-season callbacks from. We perform a Spring Start Up in March or April, reset the timer and advise the homeowner against watering every day. We leave, they reset the timer for every day, and then around the middle of July I'll get the call, "Mike, I thought you adjusted my system? I've got all these brown patches developing around my yard, I don't think I'm getting good coverage." If you would dig up a shovel depth of dirt, you would see that their root depth would be around 1" - 1.5." You should see root depth on healthy turf grasses around  5" - 6." Their system is adjusted fine, but the plants don't have enough roots to draw water from when the temps hit the 90's and above.

   We can prepare our landscapes for droughts by training our plants to grow deeper root systems. The goal of our sprinkler system should be to soak the ground to a depth just below the existing root depth. Roots will not grow into dry soil searching for water, but they will grow into wet soil providing all their other needs are being met, oxygen, light, nutrients, etc. A grass or plant that has a deeper, more extensive root system will have a larger well to draw from, so to speak, as water becomes scarcer in the soil.

Here are some things that you can do to prepare for a drought.

* Spring Start Up. A yearly tune up and re-evaluation of your irrigation system is a great start. A competent adjustment will keep the water where it needs to be and not on the driveway or street. Performing this check early in the season will give you advance warning of any problems that may need to be resolved while it's not an emergency issue.

* Switch to a warm season grass if possible. Turf grasses that go dormant during the winter require less water overall, and are much more drought and heat tolerant. In my experience, Bermuda, Zoysia, Centipede, and the other varieties are just tougher than Fescue. Some varieties also require much less nitrogen and pre-emergents, which is a bonus to the environment. Of course, your turfgrass selection can be largely dependent on your location or agricultural zone.

* Practice Xeriscaping. This is a new landscaping method that carefully selects shrubs and ornamentals native to the area being used, and also have a low water requirement. Some xeriscapes require very little additional watering, and lend themselves well to low volume drip irrigation. Drip and microspray systems can be easily configured to irrigate precisely where it's needed at slow application rates, preventing evaporation and runoff.

What can we do to minimize the damage once the drought has started? Here are a few strategies to cope with elevated temperatures, reduced rainfall, and watering restrictions that may only allow watering twice a week.

Mulch them if you love them! A proper 2 - 3" layer of mulch will hold down the evaporation from the soil. Don't overdo it, though, too much mulch can strangle and suffocate a plant. We routinely see mulch depths of 10 - 12"!

Breaking wind? No, we're not about to descend into middle school humor! I'm talking about actually protecting your landscape from excessive wind. Air blowing constantly across turf or other plants can greatly increase the amount of water transpired. Use hedges or rows of trees strategically to break the flow of wind. On some properties, this could improve net efficiency by 20 - 40 %.

* Hold back on the fertilizer. (If you can't continue to water, that is.) We wouldn't recommend abstaining from all fertilization, but a reduction is definitely wise. Nutrients will promote new growth, which requires more water.

Mow taller and less frequently. This follows our logic in the fertilizer area, more cutting promotes more new growth., which again requires more water.

* Stay after the weeds. Uninvited species will compete with your turf and ornamentals for the available resources in the soil. Many turf species, when kept healthy, can naturally keep weed growth to a minimum. Once that grass becomes weak and unhealthy, it's a different game. Weeds will take over and require more chemicals or effort to eradicate later.

*Observe run-off or other inefficiency. There is a problem with clay dominant soils. As these soil types lose available water and move closer to the permanent wilting point, the particles become denser and develop an even slower infiltration rate. A hard crust may even form on top of the ground. When one observes excess water puddling up or running off of irrigated areas, it's time to consider a different strategy, the cycle and soak method.

Cycle and soak. Multiple cycles executed with an hour or so between is a great strategy if you've been confined to only two days of watering. This method is also excellent for dealing with soils of a heavy clay content or radical slopes. Consider this example: We have a property that has a top layer of 1" of silty loam topsoil that probably came with the sod. Underneath is primarily hard pan clay, compacted from the home building process. There are 3 zones of rotors that water the turf for 40 minutes per zone, with one start time of 5am. We've calculated the watering requirements and really need 40 minutes of watering, but after each zone runs, we see large amounts of water cascading down the driveway and forming a small stream down the street to the drain. What we should do is reduce each zone's run time to 20 minutes, and switch to two start times. We'll keep the original start time of 5am and add another for 3am. This gives us the 40 minutes of run time that we need, in two 20 minute sessions. The hour and 40 minutes between each zone's cycles provides plenty of time for the first application of water to soak in and be ready to accept the later application without runoff.

   So, after reading our advice, are you still dreading a drought? Proper preparation can ease our anxieties and help our landscapes survive!  Take the time today to evaluate your property and irrigation strategy, it may be time for a change! If you have other strategies, let us know in the comments.

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