Creeping bentgrass (Agrostis palustris Huds.) green characteristics mainly depend on the sand green construction method. This study was conducted to investigate the effects of sand rootzone depth and green age on water infiltration rate (WIR) and other green responses. In 1994, different depths of sand rootzone (15cm, 30cm, 45cm, and 60cm) were set on a gravel sub-layer with colgate pipe for drainage within a lysimeter (2m×2m×0.9m) at Chiba Prefectural Agriculture Research Center. On these fields, creeping bentgrass was sodded and mowed 3 times a week at a cutting height of 5 mm under non disease control. In the first year after sodding, it was indicated that WIR decreased as rootzone depth decreased: 15cm (156mm/hr) <30cm (310mm/hr) <45cm (642mm/hr) ≤60 cm (694 mm/hr) . In addition, WIR in each rootzone depth decreased with green age. Consequently, each WIR after 7 years (2001) was reduced by 7% (15 cm), 14% (30 cm), 30% (45 cm), and 59% (60 cm) to those initial rates respectively. As for other green responses, it was observed that thatch accumulation generally increased in reverse order to sand depth. Surface hardness of each of the plots was similar except for the 15 cm plot which had low values. Moss (Bryum argenteum Hedw.) developed especially in the 15 cm and 60 cm plots, and less in the 30 cm plot. Summer turfgrass quality was higher in the 30 cm plot, but lower in the 15 cm plot evaluated in the 6th or 7th year after construction. According to these results, a depth of 30 cm to 45 cm is desirable for sand-based rootzone in creeping bentgrass putting greens.

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This study was conducted to investigate the seasonal changes of turf condition among seven creeping bentgrass (Agrostis palustris Huds.) cultivars, ‘Crenshaw’, ‘Dominant’, ‘1-93’, ‘PennA2’, ‘Penncross’, ‘Southshore’ and ‘SR1119’ in northern-part of Kyushu. Turf condition for all cultivars were higher in spring or autumn than in summer, but Crenshaw and 1-93 in particular recovered quickly after summer damage. Summer turf condition could be expected from spring turf condition and leaf anthocyanin development in last winter. Practical evaluation of turf quality should be carried out for Crenshaw, L-93 and PennA2, which maintained better turf condition compared with Penncross in this study.

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