Evaluation of Climate-Based Controllers for Landscape Irrigation.

Evaluation of Climate-Based Controllers for Landscape Irrigation

Urzagaste, Paul; Kopp, Kelly

Department of Plants, Soils & Climate, Utah State University, 4820 Old Main Hill, Logan, UT 84322

Water conservation is an important resource issue today. Daily, 96.9 million m³ of water are consumed in the United States, of which approximately 24.7 million m³ (25.5 %) is used for watering lawns, plants, and gardens (Vickers, 2001). In Utah, water is a limited resource; it's the second most arid state and is prone to droughts. In addition, Utah is one of the fastest and most highly urbanized states. Therefore, residential and commercial landscape watering is a large potential source of water for achieving the goals of urban water conservation. Climate-based irrigation controllers, also known as “smart controllers”, have been developed as one technological approach to achieving landscape water conservation.  These controllers measure the depletion of available plant soil moisture in order to operate an irrigation system. The main objectives of this study were to evaluate the applicability of “smart controllers” in a field setting and to determine whether different climate-based irrigation controller technologies achieve different levels of landscape water conservation without negatively impacting landscape quality. The experiment took place at USU's Greenville Research Farm, in an area of 930m², divided in 20 small plots of 28m² each. The plots were composed of an area of turfgrass (21m²) and another of ornamental plants (7m²). Four treatments were evaluated, with 5 replications each and arranged in a randomized complete block design. Each treatment represented a different controller and two of the treatments used on-site climate sensors [HTR][WTM] while one received a paging signal with climate data [RNB].  In addition, control plots [CTRL] were programmed using the recommendations of USU Cooperative Extension. Measurements of water applied and soil moisture were collected.  Stomatal conductance of the perennials Euonymus alatus and Paeonia lactiflora, and water potential and surface temperature of the turfgrass Poa pratensis L. were also collected.  Plant quality was measured for both the turfgrass and the perennial plants. Preliminary results showed statistically significant differences in water application for the different treatments.  The WTM, RNB, and HTR treatments applied 49, 59, and 60%, respectively, of the recommended water application rates of the CTRL treatment. Soil moisture results from CTRL treatment were significantly higher than the rest of the treatments. Consequently, turfgrass surface temperature measurements for the CTRL treatment were significantly lower than the rest of the treatments. No significant differences were found in water potential or stomatal conductance among the treatments. On turgrass, CTRL treatment shows significantly higher quality ratings than the rest of the treatments on specific days. No significant quality differences were observed in the perennial plants evaluated.

Key Words: Smart controllers, climate-based controllers, landscape, water conservation, turfgrass, perennials.