Drip Irrigation

Drip irrigation should be the method of choice for flower and vegetable beds. Underground or under-mulch drip irrigation is the most efficient water conserving method. Less water is required, and less chance for long-term irrigation saline build-up. Drip irrigation can also be used above ground. Drip irrigation systems with individual emitters do not water the entire area uniformly but just the root zones of the selected plants.

Drip systems can be purchased in kits either locally or from catalogs, or the components purchased separately to custom-fit your particular beds. However, not all drip systems are alike. One company's ½" hose connector may not snugly fit another's. Parts from different companies may not be interchangeable. Purchase all components from the same company and of the same type of irrigation system.

Drip irrigation can be hooked up to water outlets or hoses and uses soft plastic tubing that allows for emitter lines and nozzles to be placed to specifically moisten the root zone around individual plants. Emitters with varying water outputs can be attached, applying exact amounts to specific plants within the bed. Drip lines with pore holes can be used for water seepage or with laterals and emitters.

It is easy to attach a timer to the hose or drip line and to change the layout once conditions or designs change and your landscape matures. As trees, shrubs and herbaceous perennials mature, their root zones expand outward, as well as downward. Adjust the drip system for the outwardly expanded root zone.

Benefits of Drip Irrigation

For the Panhandle's climate, a drip irrigation system offers many benefits.

• One of the main advantages of drip systems is the ability to easily regulate the exact amount of water to a zone, or plant by changing the emitter and/or flow rate.
• Precious irrigation water is not lost through wind or sun evaporation, or from runoff.
• Evenly moist conditions are easier to maintain, and are better for the soil life and the plants growth, yield and health.
• Drip irrigation does not splash water on foliage, thus reducing salt burn, and disease problems such as powdery mildew, leaf spot, and fungus. The lack of splashing reduces the broadcasting of fungus and mold spores and prevents leaves from becoming muddied.
• Reduces runoff on sloped areas by controlling the flow-rate of water to proper absorption level. Vegetation planted for erosion control takes hold faster.
• Pressure compensating emitters allow for even irrigation in uneven terrain.
• Drip irrigation slowly soaks into the soil, maintaining better soil structure. Puddling water can cause clay particles to stick together and compact the soil. Soil crusting is prevented by drip irrigation.
• Helps to minimize weeds by watering near the root zone of the plant, not the entire bed. The larger areas of soil in between the plants are dryer, preventing weed seed germination.

Drip Drawbacks

No system is without maintenance; observation is still necessary.

• One drawback in buried systems: it is easy to cut through the soft plastic tube with a spade or hoe if not careful, and rodents may nibble on them.
• Drip holes and emitters get clogged and may not be noticeable until it's too late and the plants wilt.
• Cleaning filters and flushing out the lines is required twice a year. To flush the drip system, remove the drain cap at the end and run the water through. Double or triple the irrigation time at least twice a year to flush out salts and other mineral buildups.

Some people object to drip irrigation. For them, it is relaxing to just stand outside in the evening or morning to water by hand, enjoying the outdoors. For those gardeners who enjoy the relaxing activity of hand watering with a hose, consider boosting the garden at the same time by feeding it. A bi-monthly spraying with horticultural molasses, compost tea, aerobically activated compost tea, liquid humate, seaweed or fish emulsion, either separately or in combination, are good organic products to use. These are good foliar mixes that add to the health and vigor of the soil and plant.

Automatic Sprinkler Systems

Above ground automatic or manually controlled sprinkler systems are a great convenience to the gardener and lowers the gardener’s maintenance work and time. A well-designed irrigation management system can use water efficiently. A well managed irrigation system consists of a properly designed and installed system with routine observation and maintenance and a schedule that defines how long to water, when to water based on the weather and the landscape conditions.

Irrigation Audit

To determine the efficiency of an irrigation system, perform an irrigation audit. This can be as simple as a site inspection for effectiveness, noting wet or dry areas after irrigation. Are all the heads working properly, without obstruction? Are their any leaks in the lines? It’s important to note whether plants have matured and obstructed sprinklers during the growing season, as well as at the start of the season.

Identify microclimates and determine if these areas are receiving adequate water, or too much, and adjust sprinkler heads and irrigation periods for each zone. Are mixed beds (that is, low, medium and high water-use beds) tied into the same zone? Do some of the sprinkler heads need to be capped off?

Check sprinkler pressure, ensuring a spray with droplets rather than a fine mist to lessen evaporation. Install a pressure regulator, if necessary.

Determine whether any part needs repair or replacement: such as aligning and straitening sprinkler heads, replacing leaking valves and sprinkler seals and nozzles. Is a leak in one of the lines evident?

Irrigation Schedule

A watering schedule that meets, not exceeds, the water needs of the plants is extremely important for efficient use of water. It is import to know the output of the sprinklers as it runs through its cycle. Place numerous catch cans or tuna cans to measure not only the output during a 15 minute cycle, but the uniformity of distribution within the zone. Coupled with the evapotranspiration data for low (Buffalograss), medium (Bermudagrass) and high water (Bluegrass and Fescue) turf grasses and plant groups, adjust the time of the cycles for these corresponding zones.

For high water use turf (Bluegrass and Fescue) areas in clay soil that are sloped, you may need to employ an irrigation plan of cycle-and-soak. Clay soils have low infiltration rates. To provide adequate water to these areas and at the same time avoiding runoff, the cycle-and-soak method of watering 8 – 15 minute cycles. Maximum infiltration for clay loam is .13 to .25 inches per hour. (Coarse sandy soil is .72 – 1.25 inches per hour, medium loam soil is .25 - .75 inches per hour). Provide adequate time between cycles for water to filter down.

Watering schedules are made to be broken, or changed. For efficient use of water, the watering schedules need to be adjusted for weather conditions, in particular, because of rainfall and during windy weather. And again, adjust the watering schedule as the gardening year progresses through spring, into the hot summer, the cooling fall, and cold winter. For efficient use of water and better health of the plant, water according to the plants’ needs. Rain sensors are available to override automatic sprinkler systems.

To request a free copy of an Irrigation Audit Manual, and other publications offered by the City of Albuquerque, NM, go to www.cabq.gov/waterconservation/form.html.

Other Watering Systems

Choose sprinklers that produce droplets, rather than mists to lessen evaporation.

Choose an above ground sprinkler that waters close to the ground, rather than high up in the air. There will be less time for the water to evaporate before it reaches the soil.

Know how long it takes to water an inch of water. Use the catch can or tuna cans method. Place 5 – 9 clean tuna cans in various locations among your sprinklers. Water for 30 minutes and measure the water level in the cans. No watering system waters evenly. Even a slight breeze can affect the distribution of water. For best results, perform the catch can method with winds under 5 mph.

Install timers on manual hose watering systems to avoid over/under watering.

Criteria for formulating watering schedules using the manual hose and sprinkler systems are similar to the automatic systems:

• Determine the right amount of water for plant beds according to weather conditions.
• Determine the proper frequency of irrigation based on the water storage capacity of the soil.
• Place sprinklers for even distribution with minimal air exposure and at a pressure to minimize evaporation.

According to the features of your manual irrigation system and the characteristics of your landscape, determine maximum runtimes, while avoiding runoff.

Angie Hanna