“We are excited to demonstrate the RZWS and measure its effectiveness for providing root zone aeration and deep placement of water, which are critical for tree survival, and at the same time conserving landscape water.”
As a leader in agricultural and environmental sciences, the University of California at Davis is among the most widely published and cited research institutions in the world. The university strives to promote agricultural, environmental, and social sustainability through research, teaching, and public engagement. In line with that goal, the UC Davis California Center for Urban Horticulture (CCUH; ccuh.ucdavis.edu) — along with dozens of companies, agencies, and private donors — launched SmartLandscape at UC Davis, a comprehensive horticultural innovation center focused on monitoring water use and reducing urban landscape waste. SmartLandscape puts irrigation design to the test by combining low-water-use plants with the latest technology. As a hub for research, SmartLandscape connects industry professionals with researchers and students to provide policymakers with critical insights on water conservation.
Planting trees in urban settings comes with a unique set of challenges. Newly planted trees are susceptible to low survival rates usually due to poor root system establishment. For young trees to thrive, they must receive adequate irrigation and a steady exchange of oxygen across all levels of the root zone. Traditional methods of tree irrigation include overhead bubblers and tree rings, but these methods can lead to shallow root systems, especially in drought conditions. Water loss due to evaporation and runoff is also a concern. Deep-root watering — where water, oxygen, and nutrients are delivered directly to the root system — has emerged as an effective method for irrigating trees.
To demonstrate the effectiveness of deep-root watering, SmartLandscape student team members planted three small trees. They equipped each tree with two 18" (46 cm) Hunter Root Zone Watering Systems (RZWS). The RZWS is engineered with patented StrataRoot™ technology, a series of internal baffles that direct water, oxygen, and nutrients directly to the root zone and provide rigidity to the irrigation cylinder for added durability. The design encourages roots to grow deep and remain safely below ground, allowing trees to become strong and fully established. Pre-assembled for easy installation, the RZWS also includes an enclosed design and grate to protect essential irrigation hardware from vandalism. As recommended by the state of California’s Model Water Efficient Landscape Ordinance, the RZWS is an ideal solution when irrigating trees separately from the surrounding landscape.
Over the next few months of the experiment, the young trees at SmartLandscape were watered every other day for five minutes. The RZWS provided a steady irrigation flow and exchange of air for the roots that ultimately led to healthier and stronger trees. This approach proved to be an effective method for maximizing water-use efficiency while promoting strong, deep root growth. Future plans include installing a Hunter Soil-Clik® sensor to measure soil moisture and water movement around and below the tree root system and measuring applied water with the HC Flow Meter.