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Roof-Reliant Landscaping™ Step 14C: Other Factors to Consider
• Factor in the seasonal demand. Throughout New Mexico, the period of heaviest supplemental irrigation is typically late June through early July. Using July as the benchmark for maximum supplemental irrigation needed (100%), all other months need less irrigation. For example, in Las Cruces during the month of April, irrigation controllers should be set to deliver only 41% of the total water that is needed for the hot month of July. See Appendix 5 for a chart of monthly waterbudget settings for eight New Mexico locations.
Figure 6-1:
• Most drip emitters measure water delivered in gallons per hour. To convert irrigation run times to total gallons delivered, multiply the total number of hours times the flow rate of the emitter. For example, a 4-gallon-per-hour emitter that runs for 30 minutes three times a week will deliver 6 gallons of water per week (4 gallons/ hour x 0.5 hours x 3 = 6 gallons).
• Location of drip emitters is important. Watering plants too closely to the middle of their rootareas does not encourage roots to expand outward. Another common mistake is locating drip irrigation emitters too close to the trunk of a tree or the stem of a plant. Emitters should be placed at the “dripline” (the edge of the leaf canopy) of shrubs and trees. As plants grow larger, the drip emitters should be moved outward toward the dripline.
• Irrigation system efficiency. No irrigation system is 100 percent efficient. Drip irrigation systems, which are recommended for all roof-reliant landscapes, are the most efficient irrigation systems. But even drip systems lose water to leaks, improperly placed drip emitters and other factors. According to irrigation industry statistics, drip irrigation systems have an efficiency rating of 85 to 90 percent. (This means that 85-90 percent of the water entering the distribution system actually makes it to plant roots. The remaining 10-15 percent is lost to leakage or does not make it to plant roots.)
• Soil types impact run times. Sandy soils quickly direct water down and away from the root zones of plants, while soils with high clay content tend to saturate quickly, sometimes choking the roots of plants. In sandy soils, shorter and more frequent run times can be more effective. Conversely, longer time periods between run times is a good watering strategy for clay-based soils. (See Figure 6-1 above for an illustration of how soil types affect the dispersal of water into the soil.)
• Regularly inspect plants. Plants that are receiving too much water often display symptoms similar to plants that are getting too little water, such as yellowing leaves. Therefore, determining the cause of plant stress early on can help reduce your water use.
01/06/2016 | (0) Comments
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