Using Low-Altitude Thermal Sensing for Precision Management of Crop Stress.

Thermal imagery from satellites have recently been used to provide spatial estimates of crop evapotranspiration (ET) at moderate spatial resolutions (100-meter scale). Recent surveys provided by low-altitude aircraft and unmanned aerial vehicle (UAV) systems, however, have provided ET products at even finer spatial resolutions (sub-meter scale). Currently, such systems are limited for wide-range operations because it is unclear the extent to which these sensors are accurately capturing conditions on the ground. Therefore, the overall goal of this project was to assess the capability of aircraft and UAV thermal imagery for the purposes of providing spatial estimates of ET. Within a 40-ha irrigated cotton field in Central Texas, two eddy covariance (EC) towers were first installed on silt loam and silty clay soils. Low-altitude surveys from both aircraft and UAV-based systems were then flown over the field followed by ground-truth measurements such as Leaf Area Index (LAI) and plant height. Our preliminary results indicate that low-altitude thermal imagery can be useful in production agriculture where such information can help identify crop stress, particularly areas with large spatial extents.