The effects of several soil amendments, following a single filling of core aerification holes, on growth and transpiration of ‘Tifdwarf’bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt Davy] were examined during drought stress. Soil amendments had variable effects on turf quality. In general, turf grown in ZeoPro®-and Profile®-amended sand had the highest quality. Data indicated that the evaluated soil amendments have the potential to influence soil water content, ultimately influencing transpirational response to drought stress. Amended sand contained 1% to 16% more transpirable water compared with non-amended sand. Turfgrass grown in Axis®-and Isolite®-amended sand required 0.4 to 1.4 days longer to reach the endpoint (transpiration rate of drought stressed plants< 12% of well-watered plants) during a period of rapid water depletion. Data from this study suggest that the total volume these amendments occupied in the root zone, following a single filling of core aerification holes in sand, may positively influence soil moisture status, resulting in an increase in drought avoidance.

Modern golf greens are constructed using root-zone media consisting primarily of medium to coarse sand (0.25–1.00 mm). The highly permeable sands resist compaction and have adequate aeration, infiltration, and percolation, but poor nutrient and water retention. During construction and maintenance, golf green soils are often amended to improve resiliency and nutrient and water retention (Beard, 1973). Decomposed peat is the organic material most commonly used in rootzone modification. Although organic amendments increase water and nutrient retention, they decompose with time. Thus, an amendment is needed that will increase water-and nutrient-holding capacity while remaining stable over time. In general, plant transpiration responds to water deficits on the basis of the fraction of total extractable water in the root zone (Ritchie, 1980; Sinclair and Ludlow, 1986; Weisz et al., 1994). The point at which transpiration begins to decline relative to the fraction of transpirable soil water (FTSW) reflects the point at which stomata begin to close and photosynthesis begins to decline. The purpose of this research was to examine the effects of several soil amendments currently marketed for golf green use on transpiration of ‘Tifdwarf’bermudagrass during drought stress and their influence on drought stress avoidance.