TY - CHAP A1 - Rosso, Pablo A1 - Wallor, Evelyn A1 - Seserman, Diana-Maria A1 - Wehrhan, Marc A1 - Richter, Lars ED - Leibniz-Zentrum für Agrarlandschaftsforschung (ZALF), T1 - Measuring nitrogen in crops at different scales and levels: a comparison of sensors BT - Book of Abstracts T2 - Landscape 2021 Diversity for sustainable and resilient agriculture, Online conference, 20.-22.09.2021 N2 - Crop sensing technology is in continuous development. Proximal and remote sensors measuring different physical properties of plant tissue, as surrogates for nutritional and health status are being developed in response to the ever-increasing need of quick and reliable crop monitoring for precision agriculture. A recently developed fluorescent-based device, Multiplex, is of particular interest for high spatial resolution modeling and managing systems, given its capacity of measuring fluorescence properties of chlorophyll and other pigments at both leaf and canopy levels, and both in discrete (“one-shot”) and continuous (“on-the-go”) measuring modes. The goal of this research was to assess the ability of Multiplex to measure nitrogen (N) content of different crops and compare it with the performance of other well-established sensors. Several fields with spring and winter barley and corn at three locations in Brandenburg representing different levels of N fertilization were chosen for the measurements. Leaf N content (% weight) from plant samples was compared to measurements of: Fluorescence (Multiplex Research sensor), light transmittance (SPAD sensor), and reflectance (ASD Field Spectrometer). Additionally, direct canopy fluorescence (Multiplex Research sensor) was compared to canopy reflectance (ASD Field Spectrometer), light transmittance of leaf composites (SPAD sensor) and remote reflectance from multispectral sensors on remotely piloted aircrafts (RPA) or drones. Out of the 25 variables Multiplex produces at each reading, the Chlorophyll Index, the Flavonoid Index and the Nitrogen Balance Index showed the closest relationships to N. All these variables contain infrared and red fluorescence components suggesting that these have a key role in chlorophyll and N determination. In general, however, SPAD showed higher accuracy than fluorescence as a predictor of N content in leaves. Despite of this, Multiplex seems particularly convenient for fast on-field assessment of crop canopy status. At the canopy level, drone-based sensors can be as accurate as Multiplex to assess the N status of the crops under study. In the case of Multiplex, however, since the device reads are taken below the canopy and parallel to the ground, measurements are not affected by canopy density and soil background, which can be an inconvenience for vertical reflectance measurements as provided by drones and spectrometers. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-7724 SP - 100 ER -