AgIIS, Agricultural Irrigation Imaging System

AgIIS (Agricultural Irrigation Imaging System, pronounced Ag Eyes), a ground-based remote sensing system, served as a research tool that generated data for research on remotely sensed canopy level water and nitrogen status indices. A rail was mounted on a 100-m long linear move irrigation machine, and a cart with a remote sensing unit ran back and forth on the rail. As the cart traveled along the rail and the linear move traveled through the field, the sensing unit collected one square meter area reflectance measurements every meter along the rail. Because the system was automated, the remotely sensed data was acquired with low labor cost compared to traditional handheld radiometers, and provided high temporal and spatial resolution. The system monitored a 0.5-ha research area with 16 research plots. The rail, made of steel tubing, was constructed of three parallel tubes in a triangular frame. The rail had almost no vertical deflection due to cart weight, and slip joints between sections were elastic enough to absorb the deformation of the linear move when loaded with water. The sensor package included four reflectance bands filtered to narrow wavelength intervals (10 nm) in the red (670 nm), green (555 nm), red-edge (720 nm), and near infrared (NIR) (790 nm) portions of the spectrum, and an infrared thermometer. The crop spectral signals were post-processed in order to construct georeferenced field maps of vegetation, nutrient, and water status indices. Analysis of the data showed that the rail and cart provided a platform for collection of consistent and reliable remote sensing data, and it served as a valuable tool for refinement of water and nitrogen status indices. The AgIIS design effectively and reliably collected remote sensing data from a constant elevation, at near nadir orientation, and at 1-m intervals.