Daily water use (DWU) was used in two irrigation studies over two seasons to schedule irrigation. Plant DWU was determined from the difference in substrate volumetric water content over a 24 h period as measured using soil moisture sensors. Each year, irrigation was applied daily to container-grown shrubs in four treatments: 1) control application of 19 mm.ha-1.d-1, 2) irrigation applied to replace 100% DWU (100DWU) each day, 3) applications alternating 100% DWU with 75% DWU in a 2-day cycle (100-75), and 4) a 3-day application cycle replacing 100% DWU the first day and 75% DWU on the second and third days (100-75-75). The objectives between the two studies were to 1) determine whether irrigating with DWU can save water compared to a control (time-based application) rate without affecting growth of ornamental shrubs and 2) classify each taxon into irrigation functional groups (IFG). Most taxa in DWU treatments received less water than the control, yet only growth index of one taxa was negatively affected by deficit irrigation applications. Additionally, an objective of the second study was to quantify runoff volume and nutrient content from production areas irrigated under the same irrigation treatments. Effluent volumes and NO3- -N and PO43--P loads from DWU treatments were reduced compared to the control. Consequently, irrigating based on DWU also reduced NO3- -N and PO43--P losses and improved %P and %K foliar concentrations compared to the control.
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