Effectively Maintaining Turfgrass on a Water Allocation in a Mediterranean-Type Climate.

Southern Australia, like many other regions of the world, is experiencing a significant decrease in surface- and ground-water resources due to changing climate. Turfgrass managers are under pressure to restrict water use, and at the same time maintain high-quality surfaces. Water allocation is a key water planning method for irrigating turfgrass areas within public open spaces using groundwater in southern Australia. The amount of water is established by State Governments (e.g., 7500 kL ha^-1 per year in Perth, Western Australia), however its distribution during the year is at the discretion of the turfgrass manager. The objective of our three year field-based project was to investigate approaches to best manage current and possible future water allocations to turfgrass in a Mediterranean-type climate. Experimental plots (10 m²) were established on a free-draining sand from 20 year old turfgrass [Pennisetum clandestinum (Holst. Ex Chiov)] using a randomized block design. Treatments included three water allocations (5000, 6250 or 7500 kL ha^-1 year^-1), by three irrigation schedules, by three soil wetting agent application rates (nil, recommended, double recommended), by three replicates. The three irrigation schedules were calculated using historical weather data, and were further refined using either an onsite weather station or soil moisture probe. We found turfgrass quality was adequate with the current water allocation (7500 kL ha^-1 year^-1), and to a lesser extent with a water allocation of 6250 kL ha^-1 year^-1 (without traffic/wear). Applying a wetting agent improved turfgrass growth and quality (color), but not when the water allocation was lowered to 5000 kL ha^-1 year^-1. Distributing the water allocated based on historical monthly net evaporation rates was the simplest approach. Turfgrass can be maintained in a Mediterranean climate using a water allocation that is carefully distributed during the year and coupled with a wetting agent.