Velvet bentgrass putting green quality, water retention, and infiltration as affected by topdressing sand size and rate

Velvet bentgrass (Agrostis canina L.) putting greens require intensive sand topdressing programs for thatch management; however, their high shoot density combined with the low mowing heights make it challenging to maintain smooth, sand-free putting surface when topdressing is applied at high rates. A field trial was initiated to determine the effects of sand size and topdressing rate on a 'Greenwich' velvet bentgrass putting green. Treatments were arranged in a 2 x 2 factorial and included a non-topdressed control arranged in a randomized complete block design. The two factors were topdressing sand (medium-coarse sand and medium-fine sand) and topdressing rate (0.15 and 0.3 L m(-2)). Topdressing improved turf quality compared to the non-topdressed control. Additionally, velvet bentgrass had better quality when topdressed at the rate of 0.3 L m(-2) compared to 0.15 L m(-2). Increasing topdressing rate from 0.15 to 0.3 L m(-2) notably increased the quantity of unincorporated medium-coarse sand remaining on the putting surface, whereas it often did not increase or only slightly increased the quantity of unincorporated sand with medium-fine sand. Independent of sand size and rate, topdressing treatments maintained the top 0-to-3.8-cm soil profile relatively dry and increased infiltration rate measured with mini disk infiltrometers. The lack of negative effects of medium-fine sand on measured parameters and the minimum disruption to putting surface may encourage superintendents to apply greater quantities of topdressing for improving the performance of velvet bentgrass putting greens.

Automated summary

Sand size and topdressing rate have significant impacts on the quality of velvet bentgrass putting greens, with a rate of 0.3 L m(-2) improving turf quality. Increasing the rate led to a higher quantity of unincorporated medium-coarse sand, while medium-fine sand was less affected. Topdressing treatments helped maintain soil dryness and increased infiltration rates.