Tuesday, November 14, 2006
171-4
Water Budgets and Crop Coefficients for Two Contrasting South Florida Urban Landscapes.
Dara Park and John Cisar. University Of Florida, 3205 College Ave, Fort Lauderdale, FL 33314
Water used for residential landscapes must be reduced in order to protect and conserve water. Native and/or drought tolerant plants are being promoted for their presumed lower water consumptive characteristics in comparison to traditional lawns, even though little data from closely monitored, scientifically sound comparisons are available. This study investigated (water use rates (WUR) of two contrasting residential landscapes, a monoculture St. Augustinegrass (Stenotaphrum secundatum Waltz Kuntze cv. ‘Floratam’) turfgrass lawn (TG), and an alternative presumed resource conservative ornamental mixed-species landscape (MS), as well as compared WUR to a predictive evapotranspiration model (McCloud method). Rainfall, irrigation, percolation and WUR were monitored over a four-year period. Irrigation and percolate were greatest during the year 1 establishment phase. Water use rates from the TG was similar over the four years, ranging from 822 to 948 mm/yr. In contrast, water use rates increased from 728 mm in year 1 to 1,136 mm in year 4 from the MS landscape. In response to the increasing evaporative demand of an expanding canopy, irrigation increased for the MS landscape in the third and fourth years. Percolate from the TG landscape was significantly greater than from the MS landscape in year 2 (804 and 555 mm yr-1 respectively, p<0.05), and in year 4 (655 and 514 mm yr-1 respectively, p< 0.05). Average wet season crop coefficient (Kc) values for the MS and TG landscapes were not different (0.29 and 0.30, respectively), however average dry season Kc from the MS (0.67) was significantly greater than the TG (0.51, p<0.01). Although the MS landscape initially required less irrigation then the TG landscape, over time the maturing MS landscape used more water than the TG landscape.