Examining ways to conserve irrigation water on turf grass

In an effort to meet the ambitious goals set out by mandates from the CSU, CSU, Northridge (CSUN) has pursued various options for water conservation. A large portion of the University?s water consumption occurs outdoors, thus, turf removal has been a primary strategy for meeting our water reduction goals. However, turf removal is not always possible, as turf is necessary for many of our programmatic activities (sports, rehabilitation, outdoor learning, etc.). Thus, the goal of this project is to examine effective and cost efficient ways to reduce water required for irrigation, while still maintaining healthy soil that sequesters atmospheric carbon. One minimally explored and innovative approach to water conservation involves the application of hydrogel. In this process, a water absorbent polymer is injected into soil using turbulent compressed air to penetrate soil at a specified depth, creating pore spaces in the root zone. It then delivers the polymer to turf and tree roots in the form of a hydrated gel. One study found that hydraulic injection of hydrogel on turfgrass reduced water irrigation needs by more than 50 percent, with a 20 percent reduction seen in just the first 3 weeks. However, hydrogel injections are somewhat costly, roughly 30 cents per square foot, and the biodegradable polymers are expected to last only 5 years. In addition, little is known about how the water retention capacity changes as the polymer degrades. Moreover, how the composition of injected turfgrass soil compares to that of conventional methods of reducing water use and improving soil health, for example, through the application of compost, has not been examined systematically.