The Relationship Among Ball Roll Distance, Clipping Yield, and N Fertility.

Reduced putting green speed is often observed concurrently with elevated clipping production caused by intensive N fertilization. While it is generally accepted that green speed is reduced at high clipping yields and/or N fertility levels, data to verify these relations are not readily available. Field studies were conducted in 2008 to investigate correlations among ball roll distance, clipping yield, and N rate for 108 ‘Penn A-1/A-4’ creeping bentgrass (Agrostis stolonifera L.) plots (91.4 x 243.8 cm), located on either sand- or soil-based putting greens. Plots were maintained at a 3.2-mm mowing height (clippings not returned) and fertilized with N (as NH₄NO₃) from 15 to 45 kg ha­^-1 mo^-1. Clipping yield dry mass (kg ha^-1 d^-1) was collected on Jul 8, Jul 19, and Aug 13. Ball roll distance was measured six times per plot on Jul 3, Jul 17, and Aug 7, using a Pelzmeter (Pelz Golf, Spicewood, TX). Significant correlations among ball roll distance, clipping yield, and N rate were detected among the 324 data pairs. Ball roll distance was negatively correlated with both clipping yield (ρ = −0.3754; p < 0.0001) and N rate (ρ = −0.3066; p < 0.0001) while clipping yield was positively correlated with N rate (ρ = 0.27; p < 0.0001). These results confirm that putting green speed is reduced by excessive clipping production, associated with high N fertility.