A study was conducted in New Mexico from 2005 to 2007 to investigate the effects of two potable water‐saving strategies, irrigating with saline water and using subsurface systems, on changes in rootzone salinity and quality of nine warm‐season turfgrasses. Plots were irrigated using either sprinklers or subsurface drip with water of 1 of 3 salinity levels (0.6, 2.0, and 3.5 dS m−1). Plots were rated monthly for quality during the growing seasons and bi‐annually for spring and fall color. Soil samples were collected bi‐annually (June and November) and analyzed for electrical conductivity (EC), Na, and sodium adsorption ratio (SAR) at depths of 0 to 20 and 50 to 60 cm. Electrical conductivity and Na values in 0 to 20 cm peaked in June of 2005 and 2006 and dropped to lower levels after the summer rainy season. With the exception of moderately saline irrigated plots in 2005, summer EC did not differ between drip and sprinkler irrigated plots for any of the three water qualities. Electrical conductivity, Na, and SAR at a rootzone depth of 0 to 20 cm were highest in June 2006 reaching 4.7 dS m−1, 1024 mg L−1, and 16.1, respectively. For most of the grasses tested, EC, Na, or SAR values showed no significant relationship with turf quality. Drip irrigation resulted in earlier green‐up than sprinkler irrigation but had no effect on summer quality or fall color retention. Most of the warm season grasses included in this study maintained an acceptable quality level when drip‐irrigated with saline water.

ABSTRACTe limitations of the conventional visual rating system used to assess turfgrass quality include its subjective nature and the need for properly trained observers who can discern di erences among treatments or turfgrass varieties. e objective of our study was to investigate if digital image analysis (DIA) and spectral re ectance [normalized di erence vegetative index (NDVI)] can be used to evaluate turfgrass varieties. Trials were established at New Mexico State University and visual quality ratings, digital images, and NDVI were collected monthly on three warm-season and three cool-season variety trials and on one cool-season and one warm-season mixed species trial. Correlations among quality, NDVI, dark green color index (DGCI) and percent green cover (PCov) were computed. Multiple regression was used to determine if combining NDVI and DIA improved the association between visual turfgrass quality and other variables. uality was most strongly associated with NDVI (R 2 ranging from 0.37 to 0.65) for most datasets. Additionally, multiple linear regressions identi ed NDVI as the variable a ecting a higher change in R 2 when entered to the model than either DGCI or PCov. Visual quality had a weaker association with sampling date than did NDVI or DGCI, which indicates that NDVI may track quality changes more reliably over time. However, a stronger association between variety and visual quality than between variety and NDVI or DGCI indicates that a visual assessment detects varietal di erences better. erefore, it is questionable whether visual assessments can be replaced by NDVI or DIA to characterize the aesthetic appeal of turfgrasses accurately.

A 3‐yr study was conducted in New Mexico to investigate the effects of saline water on changes in quality, cover, and root zone salinity of seven cool‐season turfgrasses. Plots were irrigated using either sprinklers or subsurface drip with water of 0.6, 2.0, or 3.5 dS m−1. From March to November plots were rated monthly for quality, and green cover was determined using digital image analysis. Soil samples were collected at depths of 0 to 10, 10 to 20, and 50 to 60 cm in June and November and analyzed for electrical conductivity (EC), Na, and sodium adsorption ratio (SAR). Changes in soil EC, Na content, and SAR reflected seasonal changes in irrigation and natural precipitation and EC and Na values were highest (6.1 dS m−1 and 943 mg L−1, respectively) in June of 2006 on drip irrigated plots at depths of 0 to 10 cm. Electrical conductivity was higher in drip irrigated than sprinkler irrigated plots on four of the six sampling dates. Irrigation type and water quality did not affect EC and Na at soil depths of 50 to 60 cm. For four of the seven grasses tested, EC, Na, or SAR values showed a significant but weak relationship (0.18 < r2 < 0.27) with turf quality, indicating that more than one stressor affected visual ratings. With the exception of tall fescue [Festuca arundinacea (Schreb.)], cool‐season grasses could not be maintained at acceptable quality levels in the arid transitional climate when irrigated with saline water from either a sprinkler or a subsurface drip system.

Core Ideas We describe the use of a plant growth regulator and a soil surfactant for water conservation. We investigated whether the beneficial effects of a surfactant and a plant growth regulator on drought stressed bermudagrass were enhanced when applied in combination versus individually. We investigated if both products affect soil moisture under reduced irrigation. Soil surfactants and plant growth regulators (PGR) have shown potential to lower irrigation requirements and increase turfgrass quality under drought conditions. A study was conducted from 2014 to 2016 to investigate the soil surfactant Revolution, (modified methyl capped block copolymer [Aquatrols, Paulsboro, NJ]), or the plant growth regulator ‘PrimoMaxx’ (A.I. trinexapac‐ethyl [4‐(cyclopropylhydroxymethylene)‐3,5‐dioxocyclohexanecarboxylic acid]) (Syngenta, Basel, Switzerland), or a combination of both on percent green coverage, turfgrass color, quality, soil volumetric water content (VWC) and uniformity on Princess 77 bermudagrass (Cynodon dactylon L.) grown on a loamy sand (mixed, thermic Typic Torripsamments) and irrigated at either 80%, 65%, or 50% of reference evapotranspiration for short grass (ETOS). With the exception of plots irrigated at 50% ETos in 2015, bermudagrass receiving trinexapac‐ethyl (TE) either in combination with Revolution or alone exhibited darker green color when compared to untreated controls at all irrigation levels throughout the research period. At 50% ETos, plots treated with any of the three chemical treatments had greater quality (with 1 = worst, 9 = best) than control plots from July to September, with quality ratings of 6 or greater from June to August. Whereas VWC was not consistently enhanced by all treatment combinations, applications of Revolution, TE, and the combination of both resulted in increased VWC uniformity and greater irrigation use efficiency. Our results suggest that by using a surfactant, a PGR, or both, bermudagrass quality can be maintained with 15 to 30% less irrigation water than the optimal rate (80% ETos) without a reduction in color or quality.

Smart irrigation controllers have demonstrated potential for turfgrass water conservation in humid and temperate environments but have not been comprehensively tested in arid environments. The objective of this study was to determine the accuracy of a wireless capacitance sensor over a wide soil moisture range and to ascertain if smart irrigation controllers resulted in water savings without reducing quality of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] and bermudagrass (Cynodon dactylon L.). A two-yr study was conducted to compare turfgrass quality, root morphology, and water use of plots irrigated with a constant run time to plots for which irrigation was scheduled using soil moisture sensors (SMS), evapotranspiration (ET) [Climate Logic (CL)] controllers, or 80% of historic ET (ET80) for tall fescue and 60% (ET60) for bermudagrass. Sensors accurately tracked soil moisture up to salinity levels of 4 dS m −1. Turf performance and root morphology were not affected by irrigation treatments for either grass. Compared to tall fescue plots irrigated with constant run time, plots irrigated using ET80 and CL required 38% less water, and SMS plots used 44% less than tall fescue. Scheduling bermudagrass irrigation by ET60, CL, and SMS resulted in a 29, 42, and 39% reduction in water applied compared to constant run time. The majority of water savings was in spring and fall. Water requirement for bermudagrass during the summer did not differ between the scheduling treatments. Our study confirms that smart irrigation controllers can be used as an effective measure to conserve water in an arid environment.