Deficit Irrigation Strategies for Warm-Season Turfgrass Lawns.

Urban water resources continue to be in increasing demand, and conserving water used for irrigation while maintaining turf health is an area of growing importance.  Ten irrigation treatments were applied to 120 plots (3 x 3 m) planted with three turfgrasses commonly used in FL home lawns:  ‘Argentine’ bahiagrass, ‘Floratam’ St. Augustinegrass, and ‘Empire’ zoysiagrass.    The treatments, after establishment, were composed of both scheduled and unscheduled regimes, with or without a rain sensor.  Scheduled regimes included irrigation on a 2 d wk^-1, 2 d wk^-1 with a rain sensor, 1 d wk^-1 with RS, and an ET-based schedule.   Visual stress cues were used to trigger four of the treatments (20% to 100% of canopy wilted).  The remaining two treatments had non-irrigated and irrigated only when turf death was eminent.  Turf visual quality based on the NTEP rating scale (5.5, acceptable) and canopy firing (%) were observed weekly.  Plots irrigated based on visual cues were allowed to dry, following an irrigation event (25 mm), until the prescribed cues were perceived, at which time two irrigation events were applied (12 mm, each); this sequence was repeated between June and October 2012.

The standard 2 d wk^-1 irrigation with or without a RS applied the most water, but irrigating according to visual cues saved up to 37% over the 2 d wk^-1 schedule while maintaining acceptable turf quality.  Following first drying event in July, bahiagrass was not more than 20% fired, with no firing present by the end of the season. St. Augustinegrass plots were up to 40% fired in July, but recovered to < 20% fired under all irrigated treatments.  Zoysiagrass was up to 70% fired in July, and a 2 wk recovery period was allowed before subsequent drought stress to prevent death of the turf.  After subsequent drying cycles, zoysiagrass was <25% fired by the end of the season under any irrigated treatments.  Overall, zoysiagrass was the most sensitive to firing during the first growing season after sod establishment.