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Temporal Variability of an Active NDVI Sensor in Corn
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, First Conference on Proximal Sensing Supporting Precision Agriculture, Sep 2015, Volume 2015, p.1 - 5
Abstract
The crop of corn shows a large requirement for N, being highly responsive to nitrogen fertilizers. Among the equipment used to estimate the need for N in each point of the crop are the reflectance sensors. Active sensors theoretically have the ability to work in any time of day without interference of solar radiation or atmospheric variations, since they have their power source. This study investigated the behavior of an active sensor GreenSeeker 505 when subjected to different timetables of various solar radiation and cloud cover conditions in corn canopies. The sensor was positioned parallel to the ground, at 80 cm to the canopy of the crop, ensuring the same reading position throughout the day. Measurements were made from 7:00 AM to 7:00 PM, with a 15 minute interval between samples. The NDVI values in the V6 and R1 stages, measured by the Greenseeker sensor throughout the day were negatively influenced by the variation of irradiation. The NDVI was highest at the beginning and at the end of the day. Changes in cloud cover did not cause significant changes in NDVI.