Creeping bentgrass response to inorganic soil amendments and mechanically induced subsurface drainage and aeration

Creeping bentgrass (Agrostis stolonifera var. palustris Huds. Farw.) golf g reens often decline under the hot, humid summer conditions of the southeast ern USA. Factors associated with this decline may be poor soil aeration, ex cessive soil wetness, high temperatures, and turfgrass diseases. A field st udy evaluated a mechanical forced air system for its ability to modify the soil water content and oxygen (O-2) status of newly constructed sand-based rootzones, and its effects on turfgrass quality (TQ) and seasonal bentgrass rooting. Three drainage situations were studied: gravity drainage (control treatment) and gravity drainage supplemented by two mechanically induced d rainage treatments, water evacuation (WE) or WE followed by air-injection ( AI). In addition, the effects of peat moss and several inorganic soil amend ments on bentgrass establishment and growth were studied. Compared with gra vity drainage, WE significantly decreased water contents (0.01-0.05 m(3)m(- 3)) averaged across the 0- to 27-cm depth, with the greatest change occurri ng near the bottom of the rooting media. Seasonal fluctuations in soil O-2 and CO2 concentrations were observed, but O-2 remained high, 0.19 m(3)m(-3) , and CO2 was low, <0.01 m(3)m(-3), regardless of drainage treatment. Drain age treatments had no effect on TQ or root mass density (RMD). However, bot h TQ and RMD increased from 1998 to 1999, possibly becaue of greater turfgr ass density. Amendments had significant effects on establishment and TQ in the following order: peat moss > Ecolite = Profile > Greenschoice greater t han or equal to unamended sand. This response was probably due to improved water and nutrient retention of the amended rootzones. Although the forced air-vacuum technology provided little benefit in these newly constructed gr eens, it may be useful on mature putting greens that suffer from poor soil aeration or drainage.