Water Conservation Potential of Subsurface Drip-Irrigation on Warm-Season Grasses.

States in the southwestern region of the US face water shortages, and conservation strategies have become vital to maintain and sustain turfgrass areas. Previous studies documented that quality and coverage of warm-season grasses grown on subsurface drip-irrigation (SDI) outperformed those watered from a pop-up sprinkler system when irrigation was applied at 50% replacement of evapotranspiration for short grass (ETos). However, information is lacking on the impact on turf quality of irrigation applied below 50% ETos. A study was conducted at New Mexico State University to evaluate the effects of 25, 40 and 55% of ETos on quality of Princess 77 bermudagrass (Cynodon dactylon L.) and Sea Spray seashore paspalum (Paspalum vaginatum O. Swartz). The soil at the site consisted of a sandy loam, a sandy, skeletal, mixed, thermic Typic Torriorthent, an entisol typical for arid regions. Plots were mowed twice per week at a height of 2 cm, and clippings were collected. Irrigation treatments were initiated on 1 June 2015 and lasted until November. Grasses irrigated at 55% ETos from a sprinkler system were used as the control treatment. Data were collected monthly for visual quality rankings from 1 (dead) to 9 (best), and percent green coverage was estimated by means of digital image analysis. Overall, all irrigation treatments resulted in acceptable turfgrass quality (visual rating of 6 or higher) during July and August. In September, the lowest quality (5.8) was observed on plots irrigated at 25% ETos, and highest quality (8.3) on plots irrigated at 55% ETos. Visual quality of sprinkler-irrigated grasses was significantly lower on average, reaching 6.2 in September. Our study indicates that subsurface drip-irrigation shows greater water conservation potential when used with warm-season grasses than sprinkler irrigation does.