IRRIGATION PRACTICES |
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Even though watering restrictions are not yet commonplace throughout Alabama, homeowners should still take measures not to over water. Over watering does more than deplete the water supply; it also makes plants prone to pests and adds to stormwater runoff, which pollutes our water systems. By choosing and operating a watering system correctly, you can reduce water bills, insect and disease problems, and maintenance requirements. To maintain a healthy lawn can require as much as two inches of water per week during peak growing season. The more you water your lawn, the faster it grows and the more it needs to be mowed. Established trees and shrubs may require less than half as much water as an established turf.When severe drought leads to water restrictions, water authorities will typically restrict irrigation to certain days and times. But realize that even if it is your assigned day to irrigate, that does not mean you must irrigate. Pre-scheduled watering can waste time, money, and resources. Don’t let the calendar tell you when to water. Look not only at your plants for early signs of wilting, but also evaluate soil moisture on a daily basis.
Wilting: the drooping of plant parts, especially leaves (leaf blades folded in half, blue-gray color, and footprints remain on the lawn), sometimes because of a lack of water. However, plant wilting can also be a sign of over watering. WATERING TIPS
Overhead Irrigation or Drip?
- Reduce the need for watering by choosing water-efficient and drought-tolerant plants, including those native to your site, and plant them in the right place. If you group plants according to their water (and light) needs (called a hydrozone), you can simplify watering methods and systems. For example, turf areas and shrub areas should always be separated into different hydrozones.
- If you have an automatic sprinkler system, install a rain shutoff device or soil moisture sensor that will override the system when it rains or when the soil reaches a preset moisture level. Your county's Extension office, the Natural Resources Conservation Service (NRCS), or a certified irrigation professional can provide technical assistance.
- Water in the early morning (4-7 a.m.). This is the most efficient time because temperature and wind speeds are at their lowest, which reduces evaporation and, more importantly, drift. Also, grasses are less susceptible to fungal problems if water is applied at the time that dew normally forms.
- Avoid watering between 10 a.m. and 4 p.m. Temperature and wind speeds are at their highest during this time so water waste is more likely.
- Follow this simple watering schedule for grass: apply ½" to ¾" of water when grass shows signs of distress (bluish-gray color/folded leaf blades). Do not water again until symptoms reappear.
- If rain is predicted within the next 24 hours, delay watering.
- Use a rain gauge to measure rainfall depth.
- Experiment with gradual reductions in your watering times and frequencies to see if plants can tolerate less water.
- Be aware that little or no supplemental water is required in cooler months (November to March).
- Make sure your sprinkler system is operating properly and applying uniform coverage. Sprinkler calibration is one of the most effective ways to conserve water in an irrigation system.
- Check your system periodically for broken heads or leaks.
You are probably familiar with automated pop-up sprinklers that are part of a residential irrigation system. For lawns, those kinds of sprinklers may be the best watering method. However, for other landscape plantings, consider drip irrigation as a water-conserving alternative.Drip irrigation systems can be designed to deliver water directly to the rootzone through low-flow-rate emitters. Other micro-irrigation devices such as bubblers, micro-sprays, and misters can be used effectively if properly designed and operated. Precipitation rates for these devices are much higher than low-rate drip emitters and can apply water at high or higher rates than pop-up lawn sprinklers so it is important that they are used properly in order to avoid over-watering and subsequent runoff.
Precipitation rate: The rate, in inches per hour, that an irrigation system applies water. The precipitation rate should not exceed the infiltration rate (capacity) of the soil. Precipitation rate is a critical design component used by an irrigation professional, along with plant water requirement, to set irrigation system run times and cycles. Soil Moisture
If the soil in your yard appears dry that does not mean the root zone is dry. A soil-coring tool, like the one shown, pulls up a soil sample that allows you to see and feel the moisture in a plant’s root zone. A soil core also reveals whether you are watering so much that water is wasted below the root zone. Using a soil corer can help you judge when to water. Look for coring tools at most irrigation and some garden supply stores.INSERT PIC OF TOOL FROM FLORIDA MANUAL
Nutrient leaching can occur under certain conditions. If the system runs for excessively long time periods, the soil will become saturated. Once the soil is saturated, sandy soils found in coastal areas are more prone to leaching. However, clay soils found in other areas of the state are more prone to runoff when the precipitation rate exceeds the soil intake (infiltration) rate.
Leaching: the downward movement of water (and any particles dissolved in it, such as nutrients or pollutants) through soil. Water-wise Advice
Get practical advice on state-of-the-art irrigation systems from several sources: The Irrigation Association provides information on irrigation system selection, maintenance and appropriate watering practices, as well as links to professional organizations, manufacturers, designers, installers, and educational materials.CALIBRATING IRRIGATION SYSTEMS
Follow These Steps To Estimate How Much Water Your Irrigation System Is Applying:
- With wind conditions calm (you cannot feel a perceptible breeze on your face) turn on sprinklers for 15 minutes, recording the time of this operational test.
- Set several similar, flat-bottomed, straight-sided containers (all must be of equal size) in equidistant or equally spaced places within one watering zone. Tuna cans work well for this.
- Add the collected water from all containers into one container (must be the same size). Measure the depth of the water in the container to the nearest 1/8".
- Divide the measurement, in inches, by the number of containers used to determine the average depth of water applied in that zone in 15 minutes. Multiply this depth by 4 to get an approximate precipitation rate in inches per hour.
In the future, do not run the system any longer than needed and apply no more than ½” of water. Adjust run time as necessary based on soil type to avoid runoff or leaching.
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