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42 POTATO GROWER | FEBRUARY 2020 Diggin' In Bird's-eye view to keep an eye on potato health Eye in the Sky Diggin' In PRECISION AGRICULTURE | By Arash Rashed, Sanaz Shafian & Xi Liang Precision agriculture is a trending buzzword, reflecting the integration of advanced technologies into our agricultural practices, with the aim to optimize the decision-making process and ultimately maximize farming efficiency and profitability. One of these ever-improving technologies, known as remote sensing, has now become a powerful element of any well- monitored precision farming practice. Remote sensing can detect irregularities and deficiencies, which may impact crop yield and farming profitability if they remain undetected. Nutrient and water deficiencies; poor drainage; and weed, insect and pathogen pressures are examples of environmental factors that result in irregularities in crop production. Although frequently criticized for its lack of "detection specificity," high-throughput hyperspectral imaging (remote sensing) is now enabling us not only to detect stresses but to, in many cases, distinguish the stressor. Hyperspectral sensors can detect the presence and intensity of electromagnetic energy at different wavelengths, maximizing our discrimination power for specific pest conditions. Indeed, the majority of this electromagnetic range is not visible to our eyes. While identifying spectral information associated with individual stressors sounds like a straightforward process, there are complexities that necessitate thorough and time-intensive investigations. Information obtained through visible, multispectral, thermal and hyperspectral sensors allows us to monitor soil and crop health status and to detect variabilities. To function, these instruments mostly rely on energy from the sun, which can be absorbed (converted to heat) or reflected (detectable by electromagnetic sensors) depending on the measured surface. Sunlight intensity, however, varies throughout the day, rendering resulted measurements highly variable. In addition, crop response to any stress factor is dynamic, influenced by environmental conditions, the nature of stress, plant species (even variety), and developmental stage. Thus, thorough studies under both controlled and field conditions are required for identifying spectral signatures that are specific and can be used to distinguish the stressor. University of Idaho researchers have initiated efforts to improve the use of technologies in precision farming. Efforts are focused on using multi- and hyperspectral sensors via various platforms, including handheld devices, farm equipment, aircraft, drone and satellite images to detect abnormalities in potato crop development prior to harvest and in tubers post-harvest. Various sensors and platforms are also available to producers. The required image resolution based on the application, frequency of measurements and associated costs are a few examples of factors that should be considered for selecting a sensor or mounting platform. Here, we introduce some of these available technologies and some of their advantages and disadvantages: HANDHELD SENSORS Handheld sensors are easy to use for data collection. For instance, normalized difference vegetation index (NDVI) NDVI map generated from an image captured using a drone-mounted sensor on a farm scale. Yellow, orange and red pixelations are indicative of stressed areas. NDVI map generated from a satellite image on an area scale