Use of Infrared Thermography to Measure Water Use in Turf.

Remote sensing technologies are becoming an essential tool for precision management of turfgrass. Thermal, or infrared, camera systems are also being developed to measure turf water status. As these systems become more accessible, models need to be created to provide clear management recommendations. The goal of this study is to create an algorithm to estimate real-time water use in a creeping bentgrass putting green with thermal imagery.

The study was conducted on a creeping bentgrass (Agrostis stolonifera Hud.) putting green in Lincoln, NE. The green was monitored by a Turf-Vu Hawkeye FLIR (forward-looking infrared) camera system. Thermal and visual images were recorded every ten minutes. Soil moisture, temperature, and EC were measured with Campbell Scientific CS655 probe at 5 cm depth. Atmospheric weather conditions were recorded every five minutes from an on-site weather station. Irrigation treatments were replicated three times and included 0%, 50%, and 100% water replacement or an experimental stress index threshold. Individual plots measured 1.3m x 2.1m. Water replacement levels were determined daily by weighing a 25 cm diameter lyismeter, with the matching USGA profile, embedded in the center of each plot. Crop coefficients were calculated by dividing the actual water use rate by the FAO 56 Penman-Monteith estimate from the on-site weather station.

Canopy temperatures were found to be within 1°C of air temperature during between 1300 and 1600h until drought was visible. Drought symptoms coincided with an increase in surface temperature by 1 to 7°C depending on solar intensity. Calculated crop coefficient varied greatly depending on soil moisture status and irrigation frequency. Continued analysis will be conducted to model the small differences observed between canopy temperature and air temperature with soil moisture status. This research will lead to more precise water use estimation.