TEMPORAL VARIABILITY IN ACTIVE REFLECTANCE SENSOR-MEASURED NDVI IN SOYBEAN AND WHEAT CROPS

Optimization of N management is one of the great challenges to be overcome in grain production, as it is directly related to productivity and can also cause environmental damage. Precision agriculture aims to solve this problem by applying nitrogen fertilizer at varying rates. Reflectance sensors ar...

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Bibliographic Details
Published inEngenharia agrícola Vol. 37; no. 4; pp. 771 - 781
Main Authors Beneduzzi, Humberto M., Souza, Eduardo G., Bazzi, Claudio L., Schenatto, Kelyn
Format Journal Article
LanguageEnglish
Published Sociedade Brasileira de Engenharia Agrícola 01.08.2017
Subjects
NDVI
precision agriculture
remote sensing
vegetation index
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Summary:Optimization of N management is one of the great challenges to be overcome in grain production, as it is directly related to productivity and can also cause environmental damage. Precision agriculture aims to solve this problem by applying nitrogen fertilizer at varying rates. Reflectance sensors are instruments capable of estimating N needs in various crops, including grain crops. However, it is not clear how these sensors perform under varying solar radiation and cloud cover, due to a lack of research on their temporal variability. Thus, this study examined the temporal variability of the NDVI (normalized difference vegetation index), as measured by an active reflectance sensor, in both soybean and wheat crops. The NDVI data were collected using a GreenSeeker sensor every 15 minutes over 12 or 14 consecutive hours. Incident solar radiation was recorded using an Instrutherm MES-100 pyranometer. In all experiments in soybean and wheat, NDVI was negatively influenced by irradiation, showing higher values at the beginning and end of the day. Changes in cloud cover also affected NDVI values during the experiments.
ISSN:0100-6916
0100-6916
DOI:10.1590/1809-4430-eng.agric.v37n4p771-781/2017