HIGH-PRESSURE WATER INJECTION AND CORE CULTIVATION OF A COMPACTED PUTTING GREEN

Traditional core cultivation practices are typically performed in spring and/or fall to alleviate problems associated with soil compaction on golf course putting greens. Equipment was commercially developed that provides short-time pulse injection of highly pressurized water that could relieve soil compaction stress while limiting playing surface disturbance. This study evaluated the response of 'Penncrosscreeping bentgrass (Agrostis palustris Huds.) growing on a modified loamy sand (originally a fine-loamy, mixed, mesic, Typic Hapludalf) to hollow tine cultivation (HTC) and high pressure water injection cultivation (WIC). Cultivation treatments were applied three and two times in 1988 and 1989, respectively, on an experimental putting green receiving periodic compaction from rollers (50 kPa). Water injection was equal or superior to hollow tine cultivation in reducing soil bulk density, and increasing porosity and saturated hydraulic conductivity in the 0- to 76-mm depth zone. Hollow tine cultivation reduced soil strength by 1.33 MPa at the 30-mm depth compared with no cultivation, but only water injection cultivation provided a significant reduction in soil strength of the 70- to 100-mm depth zone. Both methods increased bentgrass shoot growth rate after treatment compared with no cultivation. Hollow tine cultivation reduced surface (0 to 100 mm) root weight density by 26%, as well as root numbers observed along minirhizotrons, compared with the check and WIC plots. Root and crown damage and root removal during HTC was the likely cause for this response. Water injection cultivation offers the potential for routine cultivation during periods of high site usage and environmental stresses with either no effect or an improvement in visual quality.