Sand Size Affects Topdressing Removed By Mowing on Putting Green Turf.

Coarse particles in topdressing sand do not readily incorporate into the canopy and thatch of putting green turf and interfere with mowing and play. A field trial was conducted to determine the effects of sand size on the quantity and particle size distribution of topdressing removed by mowing on turf maintained at 2.8 mm. Treatments included topdressing with medium-coarse, medium, or medium-fine sand and a non-topdressed control arranged in a RCBD with four replications. All sands were applied every two weeks during the summer from 2011 to 2013. Mower clippings were collected the day after topdressing with a walk behind mower. Clipping samples were combusted at 600°C for 4 h. Sand was separated from ash using a 106 μm sieve and weighed, after which the particle size distribution was determined. As expected, topdressing with medium-coarse sand resulted in more particles remaining on the turf surface compared to the medium and medium-fine sands. Up to 13% of the medium-coarse sand applied was removed by a single mowing; whereas, no more than 8% and 6% of the medium and medium-fine sands, respectively, were removed with mowing. Across all topdressing sands, 85% or more of the particles removed by mowing were coarse (0.5–1 mm) or medium (0.25–0.5 mm) sand. Furthermore, nearly half of the particles removed from the medium-coarse sand treatments were coarse sized while 91% and 81% of sand removed by mowing was medium sized for the medium and medium-fine sand treatments. Only a small fraction (< 6%) of sand removed from the medium-coarse and medium sand plots was fine sand (0.15–0.25 mm), while 14% of the particles removed from medium-fine sand plots were fine sand. Thus, topdressing putting greens with medium or medium-fine sands will improve incorporation compared to medium-coarse sand.