Evaluating the Effects of Removing Coarse and Medium Sand from Topdressing on Velvet Bentgrass Turf.

Reducing the quantity of coarse particles in topdressing sand may decrease interference with mowing and play on putting greens. However, sand <0.25-mm has the potential to negatively change the physical properties of the developing mat layer. This field trial was conducted to assess the effects of eliminating coarse and medium particles from topdressing sand on the performance of turf maintained as a putting green. Four sand sizes (medium-coarse, medium-fine, fine-medium, and fine) were applied every two weeks at 0.3 L m^-2 to ‘Greenwich' velvet bentgrass (Agrostis canina L.) turf maintained at 2.8-mm on a Nixon sandy loam (fine-loamy, mixed, semiactive, mesic Typic Hapludults) in North Brunswick, NJ. A non-topdressed control was also included. Plots were evaluated for turfgrass quality, sand incorporation, sand pick-up in mower clippings, resistance to surface penetration, and volumetric water content (VWC) of the surface 0- to 38-mm. All topdressed plots had better turf quality than the control, although turf quality never differed among sand sizes. All sands increased resistance to surface penetration compared with the control. Medium-fine sand reduced surface penetration depth compared with medium-coarse sand on 30% of measurement dates. Medium-fine, fine-medium, and fine sands required only 1 day to incorporate into the turf canopy to an acceptable level; whereas, medium-coarse sand required at least 4 days. Topdressing with medium-fine, fine-medium, and fine sands reduced the quantity of sand removed with mowing the day after topdressing by >60% compared to topdressing with coarse-medium sand. All sands reduced VWC compared with the control on 76% of measurement dates. Among topdressing treatments, fine sand increased VWC compared with the other sands on 34% of measurement dates.