Summer decline of annual bluegrass (Poa annua L.) putting greens is a major concern of golf course superintendents. Low soil water infiltration rates and high concentrations of salts in the root zone are contributing factors. This study was conducted to determine the effects of summer cultivation treatments on field infiltration rates of water, soil salinity, oxygen diffusion rates (ODR), bulk density, total and air-filled porosity, and root weight density. This research was conducted during two summer seasons (1996 and 1997) on a practice putting green located at Industry Hills Golf Courses, City of Industry, Calif. The green was constructed to US Golf Association (USGA) specifications in 1978. Cultivation treatments consisted of: 1–3) water injection cultivation (WIC) applied with a Toro HydroJect every 21 d (raised position), and every 14 or 21 d (lowered position); 4) solid tine cultivation (STC) applied every 14 d; and 5) no cultivation (check). Results showed WIC and STC significantly increased field infiltration rates of water and lowered overall soil electrical conductivity of the extract (ECe) at depths of 2.5 to 7.5 cm and 7.5 to 15.0 cm in the root zone. The effects of WIC, raised position, did not differ significantly from those of STC, but infiltration rates of water were greater on all rating dates. Cultivation treatments had no significant effects on overall soil ODR, bulk density, and porosity or on overall root weight density. nance of proper soil physical characteristics often includes soil cultivation during the spring, fall, or both, with wide-diameter tines, drills, or both, followed by topdressing. This may be the most important step for reducing summer decline of annual bluegrass putting greens and is a part of a long term program for increasing soil water infiltration rates and soil aeration porosity. However, the focus of this research was on soil cultivation during the summer, when growing conditions were not optimal for annual bluegrass. Because of increases in traffic and environmental stress during the summer, less disruptive and stressful techniques of soil cultivation are practiced. These techniques include spiking and coring with relatively narrow-diameter solid tines, or a recently developed technique involving high-pressure water injection cultivation (WIC) with a Toro HydroJect (The Toro Co., Minneapolis) or similar equipment. The WIC technique uses short bursts of high velocity streams of water to cultivate the soil while minimizing surface disruption. Murphy and Rieke (1994) evaluated the response of ‘Penncross’ creeping bentgrass (Agrostis palustrisHuds.) growing on a modified loamy sand to both WIC and hollow tine cultivation (HTC). Cultivation treatments were applied three and two times in 1988 and 1989, respectively, on an experimental putting green compacted periodically with rollers (50 kPa). They found that WIC was equal or superior to HTC in reducing soil bulk density and increasing porosity and saturated hydraulic conductivity in the 0-to 76-mm depth zone. Murphy and Rieke also noted, based on soil penetration resistance data, that WIC provided a significant loosening of the soil to the 100-mm soil depth while the HTC influence was limited to the 60-mm depth. The WIC was not as disruptive as HTC (ie, it loosened the soil less) in the surface 30 mm. The HTC also reduced the root system considerably more than did WIC, especially at the depths of 0 to 50 mm. Murphy and Rieke concluded that WIC offers the potential for routine cultivation of turfgrass during periods of high site usage and environmental stresses without reducing visual quality. How well a summer cultivation program will improve soil characteristics and root weight density of an in-use …