Soil moisture responses in traditional and drought adapted landscapes in the Intermountain West

Water conservation in the Intermountain West will be an important issue in the future as population and demand for limited water resources increases. In Utah, outdoor water use accounts for up to 60% of total per capita water use with 67% of that outdoor water being used to irrigate non native plant species to maintain a uniform green appearance. The objective of this study was to measure intra landscape changes in soil water potential during a 21.5 day dry down from DOY 215 to 236.5 in the summer of 2005 and 2006. Four, 2 x 2 replicated traditional and drought tolerant landscapes were instrumented with inexpensive resistance blocks at four points and three depths (15, 45, and 90 cm) at the Utah Botanical Center, Kaysville, Utah. Each mixed vegetation landscape consisted of a drainage lysimeter planted with annual and perennial shrubs, bunch grasses, turf grasses, and a 1.5 m coniferous tree. Mean soil water potential varied significantly between landscape treatments (p 0.05).and was most negative at 15 cm at the end of the dry down under Kentucky bluegrass (Poa pratensis. L) (-428 ± 50 kPa). In contrast, Buffalograss (Buchloe dactyloides) was significantly more negative at 45 cm and 90 cm (-291 ± 50 kPa and -197 ± 50 kPa), respectively, compared to Kentucky bluegrass, suggesting greater soil water extraction by deeper roots. Mean soil water potentials were less negative under the shrub and conifer treatments compared to turfgrasses at the end of the dry down on DOY 236.5, suggesting lower plant water use and/or hydraulic redistribution