By Kate Nolan
Green Right Now
Using less water at home is a snap indoors if you have the cash. Just install modern low-flow toilets, a state-of-the-art washing machine and dishwasher and a conserving water heater.
Outdoors, where 50 to 75 percent of residential water is consumed, the solution is trickier. Most people over-water their yards, but watering less may not be enough.
Within the backyard ecosystem, water needs can differ dramatically, based on individual plants, soil type, topography, fertilization, wind, temperature, and time of day or season. Keeping it all straight can be a prescription for madness for amateur landscapers.
One solution comes from landscaping engineers: the “weather station irrigation controller,” also called the smart controller. (Read how smart controllers work at the website of Phoenix-based SRP, the nation’s third-largest public power utility.)
Available from a number of manufacturers, the digital devices set their own watering schedules based on real-time weather data and information keyed in by the gardener. The systems may use moisture sensors or air temperature sensors to adjust the amount of watering. The watering cycle is calibrated to types of plants, soil, topography, etc., and different controllers can deliver just enough water to a variety of garden zones. Theoretically, over-watering is impossible, and manufacturers’ tests show decreased water use.
The idea is so appealing that municipal and state water conservation programs all over the country recommend smart controllers.
California started a rebate program to encourage their use, and planned to mandate it this year. But questions arose. It appears we may not be smart enough for the new controllers. While further study is done, the state has postponed its mandate.
“We thought it would be the low-flush toilet of irrigation,” said Scott Sommerfeld, a water conservation representative and certified irrigation designer at the East Bay Municipal Utility District, one of the largest water districts in California.
Instead, a 2009 statewide study of sites that switched to smart controllers shows that for 42 percent of the sites water use rose, although the majority showed modest decreases. The average savings was just 6 percent of the previous total water use at the 2,294 sites studied in northern and southern California.
Manufacturers would quibble with that. Aqua Serve, for instance, posts case studies in which all participants achieved at least 20 percent water savings with the proper use of its intelligent water controllers.
But the California study did raise questions about whether smart controllers are being used effectively and whether homeowners or cities should rely on them totally.
Smart Controllers, Smart But Not Brilliant
It concluded smart controllers were a valuable tool, but “not a ‘magic bullet’ for achieving perfect irrigation control and water savings.” The devices were seen to be only moderately effective.
Sommerfeld, who worked on the study, believes savings would increase if users were trained on the controllers. He blames the disappointing results on the controllers’ wide variety of settings and people not understanding the data they were keying in. His water district has since decreased the rebate amount, in favor of stressing savings on water bills as a motivator to reduce water use. But Sommerfeld maintains hope for the controllers, once training programs are in place.
Bay Area landscape architect Craig Hutchinson thinks mandating smart controllers will never be feasible because they require too much training to be used effectively.
“They can work, but they need a great deal of programming knowledge, constant overseeing and faith of turning over your job, if you’re a professional, or your garden, if an owner, to a computer,” said Hutchinson, an irrigation expert who is active in professional landscaping groups, and consults for water districts.
He said landscapers have a conflict of interest in programming controllers, since they get paid for keeping gardens green, rather than for keeping water use down.
11 Ways to Curb Water Use Without Compromising Curb Appeal
What most experts agree is that smart controllers would work better if their users adopted additional low-water strategies. Here are some approaches to gardening with less water in most areas of the U.S.
It means orienting your garden toward drought conditions. The basic principles include: use native soil and native plants that survive on natural rainfall, hydrozoning, efficient irrigation and mulching. (See our recent story on Xeriscape gardens.)
Group plants according to their water needs to avoid overwatering. Got a hollow where water collects? Put thirsty varieties there. Worried about that western exposure? Stick with sun-loving, drought-tolerant plants known for their resilience in challenging conditions.
Convert lawns to other uses, either by introducing drought-resistant plants or sheet mulching, in which old growth is covered by layers of newspaper, straw or other organic material and covered with an ornamental surface such as pebbles, to eliminate watering. In most places in the Southwest, typical lawn-variety grasses such as Bermuda and St. Augustine are not in keeping with water conservation. They gulp water, compared with native shrubs and flowers. Shrubs and trees can be planted through the mulch and watered with a drip system.
A top layer of pine needles, straw, shredded hardwood wood or bark over the soil can preserve moisture and prevent weeds, which can be water hogs. Read more than you ever thought there was to know about mulch at the U.S. Natural Resources Conservation Service website, brought to you by the USDA.
Most watering systems include a controller, valves and some type of water emitter. A drip system waters the roots instead of the whole plant, and uses 30-50 percent less water than sprinklers, which lose gallons to evaporation. Drip emitters consist of a series of somewhat delicate little tubes that require regular maintenance. Inline drip systems protect the emitters by placing them inside a sturdier tube that has holes in it where water is needed.
The right plant:
Reading plant tags makes it easy to identify plants that require less watering. Plants that need more water should be placed at the base of slopes to be irrigated by natural drainage.
Compost and other nutrients help soil hold water and reduce soil erosion. Apply three inches of compost to the surface and mix it in 12 inches deep.
Organic fertilization with seaweed, fish emulsion or molasses can make plants strong and better able to withstand heat and dryness. But use it sparingly because it needs water to work.
Good root growth:
Plants with better root systems suck up water more efficiently. Mycorrhizal fungi is sold commercially to build roots. It attaches to roots and increases nutrient uptake and root growth.
Multiple barrels may be needed. Used in conjunction with native plants, rain harvesting can stretch water available for irrigation. Supplement the rain by collecting air conditioner condensation.
Lawns make little conservation sense in the desert, but in rainier areas, they can make sense. New York City has a good set of guidelines that suggest watering deeply but infrequently to encourage deeper rooting and fewer weeds.
Also, set lawn mower blades a notch higher. Longer grass means less evaporation and encourages deeper rooting. Remove no more that 1/3 the height of the grass, which should be about three inches tall. Using soak-irrigation lines instead of sprinklers can lower water use by 60 percent.
Weekly watering will do. If it rains, wait another week to water. Plant drought-resistant grass such as tall fescues, instead of thirsty bluegrasses. And limit the amount of area devoted to grass.
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