Effects of within‐event aerator‐pass frequency and tine size on sand incorporation and organic matter accumulation in cool‐season putting greens of the Pacific Northwest

Abstract Aeration, when combined with sand topdressing, introduces sand into putting green root zones. More intensive aeration during a single event is becoming increasingly common to reduce the number of aeration events during a year. The goal of this study was to compare different aerator‐pass frequencies with 0.375‐ or 0.625‐inch (diameter) solid tines during a single aeration event. Experiments were conducted on cool‐season putting greens at Chambers Bay Golf Course and Tacoma Country and Golf Club during three aeration events in 2023 and 2024. Six aeration treatments included solid‐tine aeration with 0.375‐ or 0.625‐inch tines for one (1×), two (2×), or three (3×) passes using an aerator set to a 3‐inch depth on 2‐inch centers. An uncultivated control was included for comparison. All sand additions and removals were weighed to determine the amount of sand incorporated into each plot. Total organic matter was determined for depths of 1 and 3 inches before and after aeration. Sand incorporation generally increased with aeration tine size and with the number of aerator passes and was similar between 2× and 3× frequencies with 0.375‐inch tine aeration and 1× 0.625‐inch tine aeration. Total organic matter from a depth of 1 inch ranged from ∼6% to 9% at each golf course in Spring 2023 and increased through Spring 2024 only for untreated plots. Superintendents can use multiple passes with smaller tines to achieve as much sand incorporation and organic matter mitigation as traditional, “aggressive” aeration does with a single pass from larger tines.