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Advisor(s)
Abstract(s)
The sustainable intensification of forage production in Mediterranean climates requires
technological solutions that optimize the use of agricultural inputs. This study aimed to
evaluate the performance of proximal optical sensors in recommending and monitoring
variable rate nitrogen fertilization in winter forage crops cultivated under Mediterranean
conditions. A handheld multispectral active sensor (HMA), a multispectral camera on
an unmanned aircraft vehicle (UAV), and one passive on-the-go sensor (OTG) were used
to generate real-time nitrogen (N) application prescriptions. The sensors were assessed
for their correlation with agronomic parameters such as plant fresh matter (PFM), plant
dry matter (PDM), plant N content (PNC), crude protein (CP) in%, crude protein yield
(CPyield) per unit of area, and N uptake (NUp). The real-time N fertilization stood out by
promoting a 15.23% reduction in the total N fertilizer applied compared to a usual farmerfixed dose of 150 kg ha−1
, saving 22.90 kg ha−1 without compromising crop productivity.
Additionally, NDVI_OTG showed moderate simple linear correlation with PFM (R2 = 0.52),
confirming its effectiveness in prescription based on vegetative vigor. UAV_II (NDVI after
fertilization) showed even stronger correlations with CP (R2 = 0.58), CPyield (R2 = 0.53),
and NUp (R2 = 0.53), highlighting its sensitivity to physiological responses induced by N
fertilization. Although the HMA sensor operates via point readings, it also proved effective,
with significant correlations to NUp (R2 = 0.55) and CPyield (R2 = 0.53). It is concluded
that integrating sensors enables both precise input prescription and efficient monitoring of
plant physiological responses, fostering cost-effectiveness, sustainability, and improved
agronomic efficiency.
Description
Keywords
real-time fertilization automation data analysis monitoring remote sensing geographic information systems sustainability
Pedagogical Context
Citation
Silva, L.; Brunelli, C.; Moreira, R.; Barbosa, S.; Fernandes, M.; Miguel, A.; Maçãs, B.; Valero, C.; Patanita, M.; Lidon, F.C.; et al. Response of Nearby Sensors to Variable Doses of Nitrogen Fertilization in Winter Fodder Crops Under Mediterranean Climate. Sensors 2025, 25, 5811. https://doi.org/ 10.3390/s25185811
