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Light-and-frequent sand topdressing is one of the most important practices for putting greens because it smooths the surface and dilutes organic matter. However, some facilities are hesitant to commit to frequent sand topdressing because sand particles that remain on the putting surface following an application can damage mowing equipment. Coarse sand – i.e., particles greater than 0.5 mm in size – can be particularly difficult to work into a dense turf canopy. Therefore, researchers at Rutgers University have set out to determine the effects of using fine-textured topdressing sands on putting greens. More specifically, researchers seek to determine how core aeration and eliminating coarse particles from topdressing sands affects the performance of ‘Shark’ creeping bentgrass and the physical properties of a sand-based rootzone.
During a two-year experiment, combinations of three topdressing sands (medium-coarse, medium-fine or fine-medium), two topdressing application rates (50 or 100 pounds per thousand square feet) and two aeration treatments (core aeration or no core aeration) were compared against two non-topdressed control plots (Tables 1 & 2). Core aeration of designated plots occurred in May and October to remove 9.82 percent of the mat layer annually. Researchers backfilled the aeration holes with the coarsest of the three topdressing sands – i.e., the medium-course sand – because it is widely used for light-and-frequent topdressing and falls within the USGA Recommendations for a Method of Putting Green Construction. Conversely, the medium-fine and fine-medium sands contained few to no coarse particles, making them less likely to damage mowing equipment.
Results have been positive and support the use of medium-fine sands in light-and-frequent topdressing programs in conjunction with core aeration. The following points outline some of the key takeaways thus far.
- Core aeration and backfilling with medium-coarse sand reduced surface wetness and organic matter concentration.
- Core aeration decreased fine-sand particle concentration in plots topdressed regularly with the finer sands that did not fall within USGA Recommendations.
- Light-and-frequent sand topdressing increased the depth of the mat layer. Putting green turf quality improved, organic matter concentrations in the thatch layer decreased, and surface wetness decreased when using medium-coarse and medium-fine sands – i.e., sand that meets USGA Recommendations with coarse particles removed.
- Medium-fine sands increased the number of fine sand particles in the thatch layer, but this did not impact surface wetness compared to standard medium-coarse sands due to the removal of fine-particles with core aeration.
- Light-and-frequent applications of fine-medium sands did not produce drier surfaces due to the increase in fine and very fine particle concentrations.
Core aeration was the most effective cultural practice to manage organic matter accumulation in this research experiment. However, light-and-frequent sand topdressing is an effective practice to smooth the putting surface, dilute organic matter and improve turf health. Furthermore, removing coarse particles from sands that fall within USGA Recommendations can minimize damage to mowing equipment without reducing turf health or increasing surface wetness.
Additional Information:
Topdressing Sand Size and Coring Effects on Putting Green Turf (video)
Effects of Finer-Textured Topdressing Sand on Creeping Bentgrass Putting Green Turf
