|By Daniel Cunningham
Horticulturalist, Texas A&M AgriLife’s Water University Program
There’s no doubt that healthy landscapes offer a variety of advantages for the home. They not only add aesthetic value, but can also provide erosion protection, temperature control and usable outdoor space for relaxing, entertaining or growing food. Oftentimes, however, Texas landscapes are overwatered, over-fertilized or over-applied with pesticides, which can be detrimental to your landscape and to local creeks, rivers and lakes throughout our state.
The Environmental Protection Agency estimates that in drier climates (like most of Texas), a household’s outdoor water use can exceed the amount of water used for all other residential purposes. In some households, during summer, as much as 30 percent to 60 percent of a total water budget could be spent on landscape irrigation alone.
Unfortunately, in some parts of the state, water conservation has become a little bit of a divisive term. With record rainfall patterns dominating the state last fall, some may not see the need for conservation. But you may have also noticed that there are a lot of folks moving to Texas lately! In fact, the latest U.S. Census report had Texas leading in population growth last year, with both some of fastest growing cities and the largest cities in the country. With limited groundwater and surface water resources, we simply have to figure out how to do more with less water to allow for growth and prosperity in the Lone Star State.
Incorporating the best management practices and selecting the right plant material for your specific needs will drastically reduce water required for your lawn, landscape or vegetable garden and allow you to do your part to protect our state’s water resources.
Design Resilience. A healthy, water-efficient landscape begins with a well-planned design. Pay close attention to plant spacing, light availability and potential long-term maintenance requirements. Remember, a large lawn requires more maintenance and increased supplemental irrigation as compared to areas planted with regionally adapted plant material. By incorporating practical native and adapted planting areas, maintenance requirements and water requirements will be greatly reduced. Any style or theme you wish to achieve with your design can be accomplished by using water-efficient native and adapted plants.
Consider designing your landscape with equal parts turfgrass, planted beds and hardscape to increase water efficiency. A good rule of thumb is the “landscape rule of thirds”: one-third drought-tolerant turfgrass, one-third native and adapted planting beds, and one-third pervious hardscape.
Soil Preparation. Healthy soils are the foundation of a water-efficient landscape. They help to cycle nutrients, reduce runoff and have the potential to absorb any excess nutrients or pollutants. To improve your soil’s ability to infiltrate (or absorb) water and maintain soil-available nutrients, amend your soil as needed.
Water Efficiency. Compost is a nutrient-rich soil conditioner consisting of broken-down organic material. Incorporate up to 3 inches of compost into beds or pre-sodded turfgrass areas to improve drainage and increase your soil’s water-holding capacity and nutrient availability. Consider topdressing (and rake in) up to 1/4 inch of screened compost in poor-draining areas of your lawn. This technique also works well after aeration in existing high-traffic turf situations to reduce compaction and help infiltration of water. You might also consider spreading compost around newly planted trees, shrubs and perennials before you apply mulch to enhance your soil’s structure. Whether your soil is sandier or higher in clays, compost can improve your soil’s hydrology.
Irrigation Management. It is important to remember that irrigation systems are designed specifically to supplement the lack of rainfall. To transition toward a more sustainable lawn and landscape, use your system to irrigate less often but more deeply, as opposed to more often and in shorter intervals.
Properly designed water-efficient landscapes need about one inch of water per week (when rainfall is scarce). Watering in excess can actually damage the landscape by encouraging shallow root systems, which are less resilient during periods of drought. Deeper and infrequent watering will encourage deeper roots. Deep roots have access to water lower in the soil profile, where moisture is also available for an extended period of time.
If your landscape has ample soil moisture due to recent rainfall, irrigation is not necessary. Over-irrigation actually leads to increased pest issues and reduced ornamental quality of your landscape. A soil-moisture probe is an inexpensive tool that can be used to gauge soil moisture at a depth of 6–8 inches. Let the reading from this tool inform your watering decisions. Here are some more water conservation tips:
- Water your lawn and landscape after 6:00 p.m. and before 10:00 a.m. to slow evaporation rates during the active growing season, usually March–October.
- Use drip irrigation, the most efficient irrigation delivery system. It slowly applies water to the root zone, reducing evaporation. Proper design and management are key for drip irrigation to work effectively and (when used properly) to eliminate runoff.
- Install rain sensors to prevent the irrigation system from running during a rain event.
Watering Tips. If you have an automated irrigation system with a controller, or even if you rely on a hose-end sprinkler with a timer, it is important to familiarize yourself with the technology to better understand exactly how much water you are putting on your landscape at a given time. There is an easy way to give yourself a better estimate of water efficiency and prevent both under- and over-watering your plant material. A catch-can test is used to determine how long to run an irrigation system or hose-end sprinkler and how well the water is distributed over thelandscape. For example, the root zone (where water- and nutrient-absorbing roots grow) is typically 6–8 inches deep. Usually about 1 inch of water will fill this root zone, but in many cases, irrigation systems apply water faster than the ground can absorb it. Each type of sprinkler (hose-end, spray, rotors, multi-stream rotor, drip) applies water at different rates; therefore, a catch-can test is essential to determine the run time and the efficiency of the system. The following steps will allow you to learn what you need to irrigate efficiently.
- Place five to nine catch cans (tuna- or cat-food cans work great) in each irrigation zone or station.
- To determine how much water is applied to each area, run each zone with spray nozzles for five minutes; run 10–15 minutes for zones with rotors. Measure the amount of water in each catch can at the end of the specified time.
- To determine run time (the time each station should run), use this example: if there is 1/4 inch of water in each catch can after running for 5 minutes, to apply 1 inch of water, set the run time for 20 minutes (this is just an example; your measurements could vary greatly). To avoid water running off the landscape into the street, you also may need to run stations several short times instead of one long time. With this example, set the controller to run two times for 10 minutes each.
- If the water levels in the catch cans are equal or nearly equal, your irrigation system is distributing water evenly. If the levels in the can vary greatly, repairs need to be made.
- Test each zone because water application and distribution can vary by zone.
If your irrigation system is not working properly, no matter how much you water, the landscape suffers and water is wasted. Check for pipe and valve leaks (indicated by greener, faster growing grass), breaks where water is visible, clogged heads, sprinkler heads not working, misaligned heads, misting (versus spraying) due to too much pressure, water spraying onto hard surfaces and runoff into the street.
Drought Proofing. Evaporation exceeds precipitation in most parts of Texas, with long-term moisture patterns like El Niño contributing to periods of moderate to severe drought across the state. A rapidly growing population as well as limited surface water and groundwater resources contribute to the need for increased water efficiency in both urban and rural areas. The ever-increasing number of local watering guidelines — even during “normal” rainfall patterns — makes it essential to develop landscapes that are resilient to drought. But when you do, your landscape and your community will thrive for seasons to come!