Plant Factors for Irrigating Mixed Turfgrass and Shrub Landscapes in a Humid Environment

Abstract

<jats:p>Landscape water conservation methods and techniques contribute to managing water resources. Use of reference evapotranspiration (ET<jats:sub>o</jats:sub>) data and landscape coefficients is one method that needs further development. Local ET<jats:sub>o</jats:sub> data and actual plant water use were used to calculate plant factors (PFs) for three model landscapes composed of mixtures of turfgrass and shrubs. Model landscapes using a sandy loam soil included st. augustinegrass (<jats:italic>Stenotaphrum secundatum</jats:italic>), privet (<jats:italic>Ligustrum japonicum</jats:italic>), dwarf burford holly (<jats:italic>Ilex cornuta</jats:italic> ‘Burfordii Nana’), and dwarf yaupon holly (<jats:italic>Ilex vomitoria</jats:italic> ‘Nana’) at three ratios of turfgrass to shrub vegetative cover: 80:20, 50:50, and 20:80. Soil was placed into inground lysimeters in a complete randomized block design with soil moisture sensors and a drainage system. Lysimeters were irrigated with a sprinkler system, and water was applied at a rate of 100% replacement of ET<jats:sub>o</jats:sub> minus precipitation. Lysimeter soil leachate was collected from the drainage system and quantified. After 2 years, the PF of 20:80 and 50:50 turfgrass/shrub combination were greater than the PF of the 80:20 combination. Plant factors for the 80:20, 50:50, and 20:80 turfgrass:shrub combinations were 0.68, 0.97, and 1.01, respectively. There were no seasonal differences in PFs. Total growing season leachate depth over 2 years was 63.4, 30.7, and 12.6 mm for 80:20, 50:50, and 20:80, respectively. Further work on PFs should include other plant combinations, and evaluation in other climatic zones.</jats:p>