Minimum water requirements for creeping, colonial, and velvet bentgrasses under fairway conditions

Knowledge of water use requirements of various grass species is important for identifying grasses that persist with reduced water inputs and also for developing efficient irrigation management practices. This study was designed to examine minimum water requirements for maintaining acceptable quality fairways established to creeping (Agrostis stolonifera L.), colonial (A. capillaris L.) and velvet (A. canina L.) bentgrasses. Field experiments were conducted from July to November in 2002 and 2003. Plots were irrigated at four levels of irrigation on the basis of the percentage of actual evapotranspiration determined with minilysimeters (ETa): 100, 80, 60, and 40% ETa replacement. Turf performance was evaluated by measuring visual turf quality (TQ), canopy spectral parameters, canopy photosynthetic rates (Pn), and soil moisture status. Results generally demonstrated that irrigating at 100% ETa was not necessary to maintain acceptable TQ and physiological processes and that the minimum water requirements depended on species and time of year. Colonial bentgrass required irrigating at 80 to 100% ETa, while creeping and velvet bentgrasses required 60 to 80% ETa to maintain acceptable turf performance in the summer of 2002. During the summer treatment period in 2003, however, irrigating at 60% ETa was sufficient for all three species. Irrigating at 40% ETa in the fall treatment period in both 2002 and 2003 was sufficient to maintain acceptable TQ, canopy Pn, and comparable canopy growth parameters to plots receiving 100% ETa. The results from this study demonstrate the potential for significant water and monetary savings by utilizing deficit irrigation practices on bentgrass species used for golf course fairways.