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3-2 The fertilizing status and the spectral radiance facter 
The seasonal change of the spectral radiance facter were measured for 
three test field (Fig.3-1). The test field A had a base fertilization only. 
The test field B had a base fertilization and an additional fertilization 
of a nitrogenous fertilizer in the deep point of a reduction layer so as not. 
Test field C had a base fertilization and an additional fertilization of a 
nitrogenous fertilizer on the surface of the field on June 16th. 
Abattery operated hand spectroradiometer was used for the measurement of 
the spectral radiance facter. The radiometer,which had a viewing angle (14) 
with a viewing angle control aperture, was set above the rice canopy 1.5m 
vertically a-d the observation area was 18.5cm on the canopy. 
The measurement of the spectral radiance facter was done with the white 
standard, which was coated with Kodak White Reflectance Coating, for calibration. 
The white stsndard boad and the object were measured alternatively for three 
times so as to elliminate the effect of the the change in the irradiance 
of the lighy source(sun). Fig. 3-2 shows the that the spectral radiance 
facter from a flowering season to a ripping one on each fertilized field 
and on each wavelength, because the ground coverage and the Leaf Area 
Index increased, and the leaf and the ear turn into yellow , when the rice 
gets ripe. Especially the increasing slop is very steep on red band as the 
rice ear shows a remarkable yellowing phenomenon and as the relative area 
of the rice ear increases on the rice canopy. 
Fig.3-4 shows the comparision of the radiance facter on each three different 
fertilized field, where the ratio between the radiance facters in the 
non fertilized field(A) and in the fertilized(B) are used: 
log p BorC (1) —- log pA (9) 
In the visible range,the radiance factors of the two fields which were 
fertilized had a low value after fertilization and showed a difference with 
the non-fertilized fields,bud soon the difference had disapeared and could 
not identified. This phenonenon depends on the change of the leaf color 
because it was very resembles to the change of the leaf reflectivity Re(Fig.3-2) 
measured in the laboratory. 
While, in Infrared band, the deeply fertilized field (B) 
distinguished from the other two fields since the addition of fertilization 
to the flowering season. This phenomenon depends on the structure of 
the stumps (i.e. the density or the distribution of leaves) not on the 
reflectance of the components of the stumps, because that difference of the 
fertilizing condition was obscure in the reflectivity of leaves and ears 
(shown Fig.3-2, 3-3). 
Fig. 5 shows the bi-band ratio of the radiance factor 8 Gr)/ s(x), 
B(g)/ B(r). Although the B(g)/ B(r) shows the small difference 
among three fields, but ßB(ir)/ B(r) shows the great difference between 
the non-fertilized field (Field A) and the fertilized fields(Field B & G). 
These results shows that the technique of the remote-sensing 
have the capability of monitoring the fertilizing condition of the rice 
fields. And the bi-band ratio of IR and R is very effective and the data 
from taken the middle of July to the begining of August (bloOming) in 
most significant.