Crop Status Monitoring using Multispectral and Thermal Imaging Systems for Accessible Aerial Platforms

Agricultural aircraft and unmanned aerial vehicles (UAVs) are easily scheduled and accessible remote sensing platforms. Canopy temperature data for crop stress analysis were obtained with an Electrophysics PV-320T thermal imaging camera mounted in agricultural aircraft. Weather data and soil water potential were monitored and thermal images were analyzed for canopy temperature trends accounting for rainfall, irrigation, aircraft altitude, and weather. Canopy temperature responses tracked crop wetting and drying cycles fairly well, but temperature represented at the camera was influenced by the altitude of acquisition. A field application was conducted to determine changes in peanut response to four tillage regimes with the assistance of both a handheld CropScan multispectral radiometer and Fluke Ti30 thermal imager. Ground truth data included digital images for classification of surface cover and canopy closure, soil water content (0-20cm), bulk density (0-8, 8-15, 15-23 cm), and peanut yield. Preliminary analysis indicated that thermal infrared data were more sensitive to changes in the canopy response to soil conditions compared to vegetation indices derived using visible and near-infrared reflectance. Using a NASA ImageAire UAV, thermal infrared (TIR) data were sensitive to a 15% change in canopy temperature.