Comparative Water Use of Turfgrass and Ornamental Trees in an Arid Environment

D. A. Devitt
D. S. Neuman
D. C. Bowman
R. L. Morris


    Monthly evapotranspiration (ETa) of Argentine mesquite (Prosopis alba Grisebach), desert willow (Chilopsis linearis (Cav.) Sweet var. linearis) and southern live oak (Quercus virginiana Mill., nursery seedling selection) were compared with tall fescue (Festuca arundinacea Schreb.) and common bermudagrass (Cynodon dactylon (L.) Pers.) overseeded with perennial ryegrass (Lolium perene L.) over a two-year period at a field site in Las Vegas, NV.  Immature trees (56.8 L container nursery stock) and tall fescue were grown in 190 L plastic lysimeters in which weekly hydrologic balances were maintained.  Evapotranspiration of bermudagrass/ryegrass was estimated from crop coefficients (Kc) and potential evapotranspiration (ETo) predictions.  ETa of the trees and tall fescue (L/lysimeter) was shown to increase as the leaching fraction (LF = drainage/irrigation) increased.   The ETa data were compared on an area basis by dividing tree ETa by measured basal canopy areas and turfgrass ETa by the land area on which the grass was grown.   Highest tree to grass water use ratios were observed when trees (+0.25 LF) were compared to the low fertility bermudagrass/ryegrass and the lowest water use ratios were observed when comparisons were made with tall fescue under the highest irrigation treatment (+0.25 LF).  During the active growing season, tree to grass (bermudagrass/ryegrass low fertility) water use ratios in the range of 2.0 to 4.0 were observed with values dropping to approximately 1.0 during winter months.  Based on ETa-basal canopy area-canopy volume relationships, extrapolation of the data to mature size trees suggested even larger tree to grass water use ratios. 

Article published in the Journal of Turfgrass Management, Vol. 1(2) 47-63pp. 1995
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