• How to Manage Drought in Arizona Landscapes

    February 15, 2017 | Blog | bobbie
  • One of the prevalent themes that ran through 2016 and preceding years is drought and how Arizona is prepared to handle the upcoming years with reduced water reserves. It doesn’t take a rocket scientist to know that Arizona and the rest of the southwest is in a long-term drought. All you need to do is take a drive around the state to see the shocking results, like the declining lake levels and dying forests. Considering Arizona has lost over half of its water resources in the last 16 years with no expected relief in sight, the likelihood of future water restrictions is high. The first item usually hit with restrictions is outdoor/landscape watering as seen in previous years in California. Properly preparing a water management plan now can save communities and homeowners a ton of aggravation as well provide long-term economic savings.

    How Water Moves through Plants & Soils

    Having a basic understanding of how water moves through plants and soils is a good start to establishing a water management plan. Often, irrigation clocks are set and forgotten, without truly understanding how much water the landscape needs. There are a lot of factors to consider when watering landscapes efficiently. Irrigation technology has allowed us to efficiently irrigate by directing water to the plant and tree roots with tubing placed around the root ball where they will be most able to use the water. The right amount of water is important for the chemical reactions needed for plants to perform photosynthesis and keep the plant rigid, keeping the plants from wilting. Except for turf, overhead watering is not recommended for most plants and trees as much of it is lost through evaporation and isn’t efficiently absorbed through the plant’s leaves.

    Water movement through the soil is called infiltration. When the application rate of the irrigation system is greater than the infiltration rate of the soil, runoff will occur, potentially wasting large amounts of water. On the other hand, water that is applied to a
    highly porous soil such as sand, then water can be lost below the root zone and wasted. Understanding the soil you are irrigating is important, because adjustments can be made to compensate for the conditions of the soil.

    Water Deeply and Infrequently

    “Water deeply and infrequently” is a phrase quoted often by Master Gardeners and other green professionals in the horticultural industry. It simply means that it is important to water deep enough to infiltrate the root system and efficiently meet the water requirements of the plant. Knowing the soil conditions and the plant species are important to properly irrigate the plant. Per the Master Gardener Handbook, there are some general recommendations that can be helpful in knowing how deep to water.
    • Leafy vegetables and annual bedding plants: 6 inches to 1 foot.
    • Small shrubs, cool-season turf grass, corn, tomatoes: 1 to 2 feet.
    • Large shrubs, trees, warm-season turf grass: 1.5 to 5 feet.

    Watering plants to the penetrate the root zone and a little beyond encourages the plant to root more deeply and will help retain moisture. Conversely, shallow watering and too often encourages excessive soil evaporation among other unfavorable conditions including salt buildup, a ripe environment for some diseases and fungus.

    Know the ET Rate & Outside Water Resources

    Much of the water that is applied to plants is lost through evapotranspiration, also known as ET. ET rates can be determined by environmental factors including temperature, relative humidity, sun, and wind. These all effect the amount of water a plant can store and use. ET rates change daily and can be determined by checking informational resources like http://cals.arizona.edu/azmet/phxturf.html. This site is also helpful in providing lawn and landscape watering guides that can assist in creating a water management plan. http://www.arizonawaterawareness.com/, is another site that can be helpful in putting a water management plan and get tips to conserve water.

    Monitor and Maintain the Irrigation System

    Keeping a diligent eye on your irrigation system and repairing it as needed is one of the most important things you can do to ensure efficient landscape irrigation. Having a well-functioning irrigation system will help guarantee that plants are receiving the water they need. Conducting a “catch can test” is a great way to determine whether the system is watering uniformly and to see where adjustments need to made. To learn how to do this visit http://aces.nmsu.edu/pubs/_h/H510.pdf. This publication provides clear instructions and diagrams on how to do a catch can irrigation audit.

    Regularly checking and cleaning irrigation parts is a great way to find problems and keep the irrigation system running efficiently. Quickly diagnosing, and repairing minor irrigation problems can provide huge savings in preventing major irrigation problems down the road. Being consistent about plugging emitters with goof plugs where plants are missing is also another great way to ensure water savings.

    One tip important to remember is irrigation components that need to be replaced should be replaced with the same brand as the component being replaced. Each manufacturer, designs their systems’ components to work together. Replacing an irrigation component of one brand with another brand may compromise the efficiency of the entire system and is not recommended.

    Observation

    Finally, nothing beats regular observation of turf, plants and trees. Look for signs of water stress, such as wilting, burning around leaf edges, leaf drop, and less intense leaf/blade color (change from deep green to gray-green or blue-green). When signs of water deficit are noticed, then evaluate the site conditions including soil, irrigation, plant and site conditions that may be causing the water deficit. The first thing many people do when a water deficit is noticed is to increase the water. This isn’t always the best remedy; there are many conditions that could lead to water deficits in plants. Site conditions should be evaluated before determining what remedy should be applied to solve the water deficit. Some remedies could be as simple as adding mulch to decrease evaporation, aerating soil compaction, repairing an irrigation system malfunction, adjusting the irrigation schedule, or just choosing a better plant suited to adapt to the existing environmental conditions.

    Over-watered plants can also exhibit many of the same symptoms as plants with a water deficit. Checking the soil moisture content is key to determining whether a plant is being over-watered. Is the soil very wet, does the soil smell like “rotten eggs”? If these conditions exist it may be possible there is too much water, is creating “wet feet” for the roots. Roots need oxygen and need to breathe. If roots suffocate they can no longer absorb nutrients or water. They will often look discolored and can be slimy to the touch. When this happens, it is important to reduce the moisture content by reducing the water input, allow the soil to dry between irrigation run times, and if possible improve surface drainage so the roots have oxygen and space to breathe.

    Having a plan in place, should identify most of the water loss in any landscape condition. Once the problems have been identified it becomes much more simple to apply the right solution. With the plethora of resources and water education, it is so much simpler than it has been in the past to have an efficient, well-performing water management plan. Understanding environmental conditions, the water needs of the plants, trees and turf, implementing proper maintenance and irrigation practices are important tools and considerations in developing a water management plan. Being prepared for the water restrictions now and implementing water saving procedures over the next few years will be less traumatic and much easier to adapt too then being forced to comply to them at one time. Putting “water” in the bank now will help provide Arizona with the water needed for the future.

    Bobbie Potts is the Marketing and Business Development Manager for Desert Classic Landscaping. She is certified as an Arizona Contractor Landscape Professional, as a Master Gardener, as Sustainable Landscape Management professional and is an ISA Certified Arborist WE#11574A. For HOA, commercial and multi-housing landscape maintenance and tree care quotes please contact her directly at 480-249-3100 or by email at bpotts@desertclassiclandscaping.com. For more information about this and other landscape and horticultural articles please visit www.desertclassiclandscaping.com.