Soil gas, temperature, matric potential, and creeping bentgrass growth response to subsurface air movement on a sand-based golf green

Creeping bentgrass (Agrostis palustris Huds.) is used on putting greens for its fine-leaf texture, consistent speed, smooth ball roll, and year-round color. In recent years bentgrass use has extended into the warmer climates of the southern United States. Being a C-3 plant, bentgrass is not well adapted to extended hot and humid environmental conditions. Subsurface air movement systems are now commercially available that can transport air through the root zone to alter soil conditions and potentially improve bentgrass survival. This research investigated the effects of subsurface air movement on the composition of soil gases, matric potential, temperature, and growth response of a sand-based creeping bentgrass golf green. Treatments included: air movement direction (evacuate, inject, and no air) and duration of air movement (0400-0600 HR, 1000-1800 HR, and 24 hours). Treatment combinations were imposed for 13 days. Subsurface air movement reduced CO2 at the 9-cm depth to values <0.0033 mol(.)mol(-1) when evacuating or injecting air, depending upon duration. Soil matric potentials at a 9-cm depth were decreased by a maximum of 96% when evacuating air for 24-hour duration compared to no-air plots. Soil temperatures at 9 cm were decreased approximate to1 to 1.5 degreesC when injecting air from 1000 to 1800 HR and 24-hour treatments and increased approximate to0.75 degreesC when evacuating air from 1000 to 1800 HR. Subsurface air movement did not improve creeping bentgrass turf quality or rooting. Although not effective in improving the growth response of creeping bentgrass, subsurface air movement may be a useful tool to improve soil gas composition, reduce excess soil moisture, and potentially reduce soil temperature(s) of heat-stressed creeping bentgrass golf greens.