Black Sand Topdressing to Enhance Establishment of Late Fall Seeded Bentgrass Greens.

In the Pacific Northwest, USA, seeding of newly constructed golf greens often occurs later than the optimum planting date.  To determine the effectiveness of black topdressing sand to accelerate creeping bentgrass (Agrostis stolonifera L.) late season germination and establishment, a field study was conducted on a newly constructed sand-based golf green at Pullman, WA during the fall of 2007 and 2009.  Creeping bentgrass cv. ‘T-1’ was seeded at 98 kg ha^-1 on 28 Sept. 2007 and 2009.  On 5 Oct. 2007 and 2 Oct. 2009, BLACK SAND® (Grass Roots Agronomics, Inc., Emmett, ID), a black, dyed sand, or tan sand (Atlas Sand and Rock, Lewiston, ID) topdressing treatment was applied at 9,800 or 19,600 kg ha^-1 using a drop spreader.  An additional treatment was a ‘Reemay’ (Dupont, Wilmington, DE) white, spunbonded polyester (50 g m^-2) cover.  The experimental design was a randomized complete block with four replications.  Each experimental unit was 9.3 m².  Hourly soil temperature at 1.3 cm was recorded with a Hobo U12 datalogger (Onset®, Bourne, MA).  At 35 d after treatment, three random digital pictures were taken of each experimental unit and seedlings were counted in 161 cm² subsamples.  Seedling counts were highest in the black sand treatment (approximately 2.5 or 3.5 times > the conventionally seeded check in 2007 or 2009, respectively), other treatment were intermediate.  All treatments had their maximum daily temperature at 1400 h.  During mid day, the 19,600 kg ha^-1 black sand treatment was 1.4^oC > the Reemay cover and 0.9^oC > tan sand, but at night soil temperature was 1.2^oC higher under the Reemay cover.  Black topdressing sand at 19,600 kg ha^-1 greatly enhanced late fall establishment of creeping bentgrass greens.