With urbanization, significant tracts of natural ecosystem and agricultural land are being replaced with turfgrass [Alig et al., 2004; U.S. Geological Survey (USGS), 1999]. In the United States, turfgrasses are estimated to cover 16 to 20 million hectares of urbanized land, or up to 18% of the land area in some regions [Morris, 2003; U.S. Department of Agriculture (USDA), 2004, 2006]; this represents an area three times larger than any irrigated crop (Milesi et al., 2005). Furthermore, urbanization in the United States and elsewhere is projected to continue to increase rapidly (Alig et al., 2004), indicating a continued expansion of land area covered with turfgrasses.
The rapid increase of turfgrass in the landscape may have significant implications for water quality and quantity. A number of studies have linked urbanization with declining water quality in surface and groundwater reservoirs because of increased concentrations of nutrients and pesticides, some of which are used in lawns (Hamilton et al., 2004; King and Balogh, 2001; Petrovic and Easton, 2005; USGS, 2001). Irrigation of turfgrass is typical in many urban areas, which increases demand for water resources. Water scarcity is most critical in arid or semiarid regions experiencing rapid urban growth (Reisner, 1993).
Water quality in urban areas may be affected by runoff or leaching of fertilizer nutrients and pesticides from lawns, but runoff from impervious surfaces is the greatest concern. Runoff from lawns or impervious surfaces may happen during intense rainstorms, when turfgrass is over irrigated, or when irrigation systems are improperly adjusted (Brezonik and Stadelmann, 2002; Morton et al., 1988; Petrovic, 1990). The extent of excessively irrigated turfgrass is not known, but apparently over irrigation has altered the hydrologic system of the Las Vegas Valley such that historically ephemeral washes have become perennial streams in urbanized areas (Mizell and French, 1995). This indicates a critical need to change the behavior of urbanites to reduce their irrigation inputs and thus, conserve water and improve water quality.
The greatest opportunity for conserving water and minimizing runoff and leaching in urban areas may be in residential lawns. From 50% to as much as 80% of all land area covered with turfgrass in the United States is composed of residential lawns (Grounds Maintenance, 1996; USDA, 2004, 2006), and up to 75% of residential water use may be for “outdoor” purposes (Vickers, 2001). The use of automatic irrigation systems by homeowners, which increasingly are installed during construction of new single-family homes in urbanizing watersheds in some regions, may be both problematic and advantageous to water conservation efforts. On a per-area basis, in-ground irrigation systems may use twice the amount of water as manual irrigation if the systems are improperly adjusted (Vickers, 2001). However, these systems also may present opportunities for more accurate irrigation (e.g., match the minimal or actual water needs of the turfgrass) if residents are given proper education.
Inaccurate perceptions about water requirements for turfgrass or embellished expectations about lawn appearance (e.g., maintaining perfectly green lawns even during drought) may result in over-irrigation. However, data are lacking to quantify the prevalence of such perceptions, including how they affect lawn-watering practices. Presumably, the perceptions and practices of homeowners about lawn watering may be influenced by a number of factors including demographics, local climate, water costs, water shortages, and whether homeowners have an in-ground irrigation system or not. Consequently, a first step toward improving water quality and conservation in urban watersheds is to carefully evaluate fundamental perceptions and practices of homeowners in watering their lawns.
Our objective was to determine how owning an in-ground irrigation sprinkler system affected the perceptions, knowledge, and behaviors of residential homeowners about the irrigation of their lawns during summer months. To that end, survey responses were compared between those with and without in-ground irrigation sprinkler systems in three separate urban areas of Kansas, each with distinct combinations of climate, demographics, and water issues.
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