Production of Thuja (T. standishii x T. plicata) Using an Automated Micro-Irrigation System and Routine Leaching Fraction Testing in a Container Nursery1

Abstract A web-based, container irrigation scheduling program (CIRRIG) based on routine Leaching Fraction (LF=drainage/applied) testing and real-time weather monitoring was evaluated for its effect on plant growth and water use of Thuja (T. standishii x T. plicata) ‘Green Giant' in #15 [43 cm (17 inch)] containers in a commercial nursery in Florida. Independently-controlled irrigation zones each containing 830 plants were irrigated automatically with CIRRIG or with the nursery's traditional irrigation practice of a fixed daily rate. After 6 months, CIRRIG reduced the total volume of water applied by 51% [490 vs. 990 L/plant (129 vs. 262 gal/plant) but reduced growth in plant height and width by 15% and 10%, respectively. Routine LF testing indicated that the target LF of 25% was likely too low for the coarse pine bark substrate and spray-stake irrigation system. In light of stricter consumptive use permitting of water by governmental agencies, technologies such as CIRRIG may allow nurseries to produce mor...