- - AGRICULTURE CORE CURRICULUM - - (CLF6000) Advanced Core Cluster: ORNAMENTAL HORTICULTURE (CLF6450) Unit Title: IRRIGATION AND DRAINAGE ____________________________________________________________________________ (CLF6451) Topic: IRRIGATING ORNAMENTAL Time Year(s) PLANTINGS 1 hour 3 / 4 ____________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the student will be able to: Learning Outcome #: (H-1) - Define the terms irrigation and drainage. Special Materials and Equipment: Drawing vellum with 1/4" grid, drawing supplies, tape measures, architect's scales and a rod and level; flow gauge. References: Hartmann, H. T., Flocker, W. J., & Kofranek, A. M. (1981). PLANT SCIENCE: GROWTH, DEVELOPMENT, AND UTILIZATION OF CULTIVATED PLANTS. Englewood Cliffs, NJ: Prentice-Hall. [1988 2nd edition now available] Editors of Sunset Books and Sunset Magazine. (1989). WATERWISE GARDENING. Menlo Park, CA: Lane Publishing Co. Editors of Sunset Books and Sunset Magazine. (1988). WESTERN GARDEN BOOK. Menlo Park, CA: Lane Publishing Co. Evaluation: Unit Exam ===================================================================== INSTRUCTORS' NOTE This and the four following lessons deal with irrigation of plants once they are established in the landscape. For information on the irrigation of plants in the field and nursery for production purposes, please refer to (CLF6605) Watering Nursery Stock and (CFL6608) Irrigation Systems. Highly recommended to augment this unit are (CLF 7409) Soil Moisture Behavior and (CLF7410) Soil Water. ===================================================================== TOPIC PRESENTATION: IRRIGATING ORNAMENTAL PLANTINGS A. Irrigating Ornamentals in the Landscape 1. Irrigation systems are essential in a modern landscape. a. In the 1990s, landscape plantings are an integral part of nearly all residential, commercial, and public construction. b. The value of ornamental plantings is widely accepted, and substantial investment is made in beautifying the environment with plants. c. The most immediate need of these plants is water. d. Well-designed, properly installed, and well-maintained irrigation systems are critical if investment in the landscape is to be protected. 2. Many innovations have been developed for irrigating the landscape. a. The days of hand watering are over. In the USA, labor is too expensive to use for watering plants by hand and moving sprinklers around. b. In most locations, built-in irrigation systems are a virtual necessity in the landscape. c. Most of these, now, are controlled automatically, eliminating the need for people to turn valves on and off. Automatic systems also improve control over water use. d. Landscape conditions vary tremendously and demand different approaches to irrigation. There is a complex variety of equipment and technology to give us control over how water is delivered. e. To simplify, most irrigation systems can be classified as either "sprinkler" irrigation or "drip" irrigation. 1) Sprinkler systems are used mainly for turf and ground covers. Pop-up spray heads, streamers, bubblers, mist nozzles, and shrub heads are all types of equipment found in sprinkler systems. 2) Drip systems are used mainly for irrigating trees, shrubs, and container plantings, but can be adapted for a variety of applications. Drip equipment includes mini-sprinklers, soaker-tubing, and drip emitters. 3. Irrigation practices which conserve water are more important than ever. a. In most communities, landscape irrigation consumes more water than any other use. b. There are threats in many locations to the water supply. 1) Burgeoning populations need more water. 2) Erratic rainfall patterns affect some supplies, as do dwindling aquifers in other areas. 3) There is increased industrial demand for water in many locations. 4) Water quality problems due to agricultural and industrial pollutants are becoming more apparent. c. Municipalities and water districts are becoming less tolerant of wasteful irrigation practices. d. Fortunately, irrigation systems can be designed to be more water-efficient than ever before. 4. Water from landscape irrigation must drain efficiently. a. Getting water on the landscape is only "part of the story." Water must also have a way to leave the landscape. b. Water not taken up by plants must be able to drain away, or the health of plants as well as the integrity of buildings will be threatened. c. Providing for drainage in a landscape is just as important as providing for irrigation; they go hand-in-hand. B. Defining Irrigation and Drainage 1. Irrigation is applying water to the soil by some means other than natural precipitation. 2. Drainage is the removal of excess gravitational water from the soil by natural or artificial means. C. There are a number of factors to consider when planning and designing an irrigation system. 1. System installation must be scheduled carefully. a. Drainage and irrigation both involve a lot of underground work, and are more easily installed before plants, hardscape elements, and other surface features are put in place. b. At the same time, accurate placement of sprinkler heads and other parts of the system requires that certain grading and construction features be complete before irrigation work begins. 2. An accurate scale drawing of the area to be irrigated should be laid out so a plan can be developed. a. 1" = 4' is a standard scale to use for most residential and small commercial sites. b. Measurements should include significant changes in elevation, in addition to the location of buildings, walkways, decks, patios, driveways, plants, and utility lines. c. Hose bibs or other access to water should be marked. __________________________________________________________ ACTIVITY: 1. Have students map out the area surrounding the classroom or an adjacent area of the school yard which might benefit from landscaping. 2. Useful equipment includes tape measures, architect's scales and a rod and level for determining angles and elevation differences. 3. Have students work in teams of three or four, taking turns at measuring and recording tasks. Each student should turn in their own map based on the group's measurements. __________________________________________________________ 3. Permits may be required for certain irrigation installations. a. The municipality or county should be consulted. b. This is a good time to check on code requirements regarding such things as backflow-prevention devices, types of pipe which can be used, and burial depth for pressurized water lines. 4. Information on available irrigation equipment should be gathered. a. Catalogs from various manufacturers supply technical data which allow calculations such as sprinkler head spacing and flow requirements to run the system. b. Using one manufacturer's equipment on a site, rather than using a mixture of equipment, makes installation and system maintenance a simpler task. 5. Existing and proposed conditions of the site should be analyzed. a. Location and size of existing and proposed hose bibs should be determined. b. The water source should be checked. 1) The available pressure (in pounds per square inch) and flow (in gallons per minute) should be determined. 2) Find out if there are any problems with water quality, such as rust or silt or a high level of salts in the water supply. __________________________________________________________ ACTIVITY: 1. With a flow gauge, have students determine the water pressure available at the hose bib nearest to the classroom or agriculture compound. Use a flow meter to check flow as well. 2. Check the pressure with the flow shut off (static pressure). Check the pressure with the flow running (dynamic pressure) at five gallons per minute, then for two gallons per minute. Compare the results. Determine how much flow there is (in gallons per minute) when the pressure shows about 30 psi (a common operating pressure for sprinklers). __________________________________________________________ c. Test soil texture and assess permeability. The rate at which water can infiltrate the soil is important in designing and running a sprinkler system. d. Note location and water demands of existing plants. Assess water demands of proposed vegetation. Will the garden be lush and jungle-like, or a water-conserving xeriscape? e. Analyze slopes and aspect. 1) The steepness of a grade will affect water infiltration and runoff. Steep slopes cannot be sprinkler-irrigated for long without causing runoff. (This is a good application of drip irrigation.) 2) How grades face in relation to the sun will affect the rates of evaporation and transpiration. Slopes facing north and east require less irrigation. f. Determine summer and winter shade patterns because these affect demand for water. g. Determine prevailing wind directions because wind can throw off irrigation patterns and create dry spots. This must be compensated for. h. Try to anticipate how growth in the landscape might interfere with irrigation lines or sprinkler spray patterns. Look ahead and design around these problems. i. Pay attention to traffic patterns. For example, don't place sprinkler heads where they are likely to trip someone or get broken by an automobile. 6. Plan and design for water conservation. A few examples: a. Plan to use drip irrigation wherever appropriate. b. Use low-gallonage sprinkler heads to minimize runoff. c. Remember to set heads high enough to reach above layers of water-conserving mulch. 7. Try to anticipate any possible future needs. For example, if an adjacent area might be landscaped at a future date, design into your plan easy access to the water supply near that site. Some forethought in the present can save a lot of work in the future. D. Different parts of the landscape will require different types of irrigation. 1. Turf: Lawn areas are the biggest users of water in the landscape. They require even, full coverage by sprinklers. 2. Shrubs: They require water in their root zone only, and can be irrigated with drip irrigation, bubblers, or low-trajectory sprinklers. Obviously, sprinklers have limited throw around leafy shrubs, so this application for sprinklers is limited. 3. Trees: The deep root systems of trees require slow, deep irrigation. Drip, or bubblers with well-formed basins are appropriate here. 4. Planter Boxes and Containers: Bubblers and drip lines serve these areas best. 5. Ground Covers: Coverage required depends on the species used. Either sprinklers or drip can be used successfully. 6. Sloped areas respond well to drip irrigation; erosion and runoff are reduced. 1/6/91 MH/clh #%&C