   Water Conservation in the Landscape - September 11, 2002 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Since we are experiencing a drought with no relief in sight, I thought it was appropriate to focus on water conservation in the landscape. As Yavapai County's population continues to increase, I think we can all agree that landscape water conservation is the right thing to do. We need not sacrifice aesthetics to create an attractive, yet water wise garden. Rather, we should look around us and strive to recreate the beauty of our natural surroundings in our residential and commercial landscapes. It is easiest to create a drought-adapted landscape (xeriscape) from scratch. Native plants can be conserved and protected on the building site during construction by installing temporary fences that preclude access by contractors, delivery people, and others involved in construction. Although more difficult, existing landscapes can also be converted or modified to conserve water. For instance, large areas of turf can be removed or reduced, water greedy trees such as cottonwoods can be replaced with drought-tolerant species, and native grasses, cactus, succulents, and perennials can replace green leafy shrubs. Soil amendment helps conserve irrigation water and facilitates the capture of precipitation (remember what rain is?). The addition of organic matter creates larger pore spaces that allow water to more freely infiltrate into clay soils while increasing the water holding capacity of sandy and loamy soils. Any way you cut it, adding organic matter to the soil of a planted bed is a winning proposition. On the other hand, you need not spend time and money adding large quantities of organic matter to tree and shrub planting holes. Research has proven that woody plants have better survival and growth when planted directly into loosened native soil. Mulching the soil surface also conserves water in the landscape. Mulching materials come in a variety of forms: organic (shredded bark, leaves, etc.), inorganic (rock or gravel), and synthetic (not black plastic) that can be used with or without other mulch materials. Mulch works in two ways. First, by reducing the velocity or rain (or irrigation) droplets which allows them to soak in more freely, and second, by reducing evaporation from the soil surface. For more on mulching, read the December 30, 1998 Backyard Gardener column which is available on the BYG web site (ag.arizona.edu/yavapai/anr/hort/byg/). Turf is appropriate in landscapes if used wisely. The evaporative effects of a small lawn can cool the environment and reduce indoor energy costs. In areas that simply require a ground cover, there are many grass species that use little water while maintaining soil cover and mitigating erosion. These grasses can be mowed or left unmowed for a meadow-like effect. Think of these water-conserving lawns as living mulch. Select appropriate plants that are adapted to our climate and soils. Look carefully at your site. If you live in an upland pinyon/juniper forest you should avoid planting riparian species such as alder, cottonwood, or sycamore. Upland sites favor xeriscape species. After selecting appropriate plants, you must water them until established. However, once they take, cut back the water. Once established, they may live well on infrequent irrigation during times of drought. I have several areas in my landscape that I water three times per year if at all. For ideas about water conserving plant species, come visit the Cooperative Extension Master Gardener booth at Verde River Days, September 28 at Dead Horse Ranch State Park. Drip irrigation systems are helpful when establishing a drought tolerant landscape, but after the plants are established, they can become harmful to the maturing landscape. For instance, the single drip emitter that was used to establish a tree will not be adequate to water that tree after it matures. Furthermore, the roots will tend to proliferate in that wet spot and not grow into unoccupied soil beyond the wet zone. Improper use of drip systems can also apply too much water for an established plant causing it to grow more rapidly than is desirable. These fast growing plants are often pruned back in ways that are not healthy for the plant. Consider nature's pruning methods: growth in favorable times and stagnation or dieback when conditions are unfavorable. I think drip systems should only be used to establish xeriscapes and either modified or abandoned after establishment. That's my story and I'm sticking to it. See you at Verde River Days. The University of Arizona Cooperative Extension has publications and information on plant selection and irrigation. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/. |