Jerzy Kozyra, Rafał Pudełko
Zakład Agrometeorologii i Zastosowań Informatyki
Instytut Uprawy Nawożenia i Gleboznawstwa – Państwowy Instytut Badawczy
Ul. Czartoryskich 8,
24-100 Puławy
Testing of remote sensing methods using aerial and ground based methods
INTRODUCTION
The use of spectral radiation measurements in agricultural research is on the increase. The source of
spectral data is usually data from sensors installed in artificial Earth satellites or aerial photographs.
Sensors registering radiation in various spectral ranges in ground measurement devices have recently
become available. This means new possibilities of potential future agricultural applications owing to
reduced costs of data acquisition and a lesser dependence of investigations on the weather conditions.
MATERIALS AND METHODS
In the article measurement systems used at the Institute of Soil Science and Plant Cultivation National Research Institute (IUNG-PIB) in two research projects financed by the Ministry of
Education and Science are presented. The research was carried out in the fields of agricultural
experiment stations of the IUNG-PIB in Osiny near Puławy (eastern Poland) and in Baborówko near
Poznań (west north-western Poland).
The objective of the AGROCYCLUS (2P06R 078) project is a description of the yearly cycle of crop
vegetation indices. Spectral characteristics of the crops selected for research are obtained from ground
measurements of secondary radiation conducted directly above the plant canopy with the LI-1800
spectroradiometer manufactured by the LICOR company and a digital camera used for registering near
red radiation (manufactured by the Tetracom). The objective of the LOTON (2P06R 04127) project is
a verification of applicability of remote methods to evaluation of the nitrogen nutrition status. In the
project spectral photographs are taken from an aeroplane as well as from a PIXY remotely controlled
flying model. In addition the data are complemented by ground measurements conducted from a
tractor with a set of spectral sensors integrated with a SKYE data logger.
RESULTS
Spectral measurements conducted with the LICOR spectroradiometer yield spectral characteristics
with 4 nm resolution ranging from 350 to 1100 nm. However, the method does not register variability
present within the area under investigation. This poses a problem especially in early vegetation phases
when an intensive interference of secondary radiation reflected from the soil occurs. Complementary
photographs taken with an ADC camera make it possible to estimate the factual reflection area of the
plants and to differentiate their condition (example in fig.1).
Fig.1. Comparison of results obtained with LICOR spectroradiometer (full spectral characteristics) and
the Tetracam (evaluation of the variability in the crop stand structure measured by the LICOR
spectroradiometer). A) Albedo of Spring wheat at different phenological stages (at 29.04.2005 and
14.06.2005) B) SAVI index of spring wheat at 29.04.2005 and 14.06.2005
The integration of ground measurements with a positioning system makes it possible to obtain maps of
vegetation indices of the quality comparable to that of the maps based on aerial photographs (fig.2).
Fig.2. Comparison of an NDVI map obtained from ground measurements (SKYE) with a greennessindex map produced by classification of the aerial photograph.
DISCUSION AND CONCLUSION
In the article preliminary results obtained in the first realisation stage of the projects are presented. The
evaluation of remote techniques applicability carried out seems to corroborate high usefulness of
ground techniques (Adamchuk 2004). They are cheaper than remote aerial sensing and give more
freedom in measurement date planning (Brisco 1997). Integration of ground sensing with positioning
techniques allows to register spatial differentiation in the production field during real time
measurements. A replacement of aerial remote sensing with ground remote sensing conducted during
regular field operations should lead to a reduction of data acquisition costs. It will also have the
advantage of lesser dependence on the weather as well as on expensive professional aerial-material
processing.
REFERENCES
1. Adamchuk V.I., Hummel J.W., Morgan M.T., Upadhyaya S.K. 2004: On-the-go soil sensors
for precision agriculture. Computers and Electronics in Agriculture, 44 (1), 71-91.
2. Brisco D.J., de Gruijter J.J., 1997: Precision agriculture and the role of remote sensing: a
review. Canadian Jurnal of Remote Sensing, 24, 315-327.