two different 
The first one, 
ww 
99 m 
plant species 
" which alrea- 
be attained 
, sugar beets, 
touchstone for 
at field with 
have one of 
r wheat, bar- 
the rotation 
2 S 2 
2 F 2 
1 N 2 
11 m 
nter wheat 
e three inde 
parameters are 
) and nitrogen 
and fungizid 
) and nitrogen 
These parame- 
ifferences in 
on in order to 
al changes in 
her so that we 
tivation (cf. 
r the collec- 
It is divided 
into 7 small pieces (cf. fig.3). The pieces at both 
sides are reserved for reflection measurements (R), 
the adjacent ones serve for taking out plants for the 
laboratory analysis (TP) and the central piece will 
be harvested at the end of the growing season to 
determine the produced yield (H). 
21 m *• 
Figure 3 : Functional structure of a plot 
3.2 Organizational concept 
All measurements will be accomplished as simultaneous 
as possible. During the reflection measurements some 
plants will be taken out and transported to the 
laboratory for analysis of the agronomic parameters. 
The meteorologic data will be taken in parallel with 
spectral information, while the geometric shape of 
the plant targets is fixed by means of stereo pic 
tures just before the measurement cycle starts. The 
situation in the atmosphere is completely recorded on 
videotape by means of a CCD video camera for each 
cycle too. 
In each plot spectral data will be collected for 
three different targets with dimensions of 2.8*0.5 m^ 
approximately. With help of some positioning aides 
for the radiometer it is tried to reproduce the 
position of the targets for all measurements during 
the growing season. This concept assures comparable 
reflection data for each campaign, as the changes for 
one target during the growing season may give an idea 
about the development of selected plants. 
3.3 Measuring program 
The collected data may be divided into four classes : 
- 1. Agronomic parameters 
These parameters are necessary to describe the 
development stage of plants, their health and bio 
logic situation 
- 2. Structure parameters 
This means especially the geometric structure of 
the measured targets including the surface topo 
graphy of the whole target and the geometric shape 
of single plants 
- 3. Meteorologic data 
The meteorologic data describes the microclimatic 
situation in the cultivated fields and their envi 
ronment. This gives an impression in which amount 
energy like radiation, humidity or temperature is 
available for the plants. Additionally, it is im 
portant to know something about influences like 
wind, which may affect the reflection measurement. 
- 4. Radiometric data 
The field measurement of the radiation reflected 
from plant targets provides the most important 
information for the remote sensing application and, 
after correction of the raw data, should correlate 
with the produced yield. 
It is envisaged to adapt the measuring campaign to 
the course of the plant growth. In general the mea 
surements should be taken once in two weeks, while 
for times with rapid changes in the plants the fre 
quence will be higher. For the whole growing season 
at least 10 cycles should be collected, assuming that 
enough days with dry weather conditions are availab 
le. 
3.4 Measuring technique 
According to the above grouping, the measurements 
will be taken as follows : 
- 1. Agronomic data 
All collected agronomic information is listed in 
table 1. We have to distinguish between simple evalu 
ated data like weights, length values or numbers, 
subjective intrinsic values like stage of growth or 
influence of disease, and data which needs special 
equipment, as for some physiologic and morphologic 
values. 
The pigment content, for example is determined with 
help of spectroscopy, the internal structure of 
leaves will be derived from small thin slices of cell 
material, while potassium, sodium, nitrogen, and 
sugar content are measured chemically. 
All these values will be evaluated for different 
parts of the plants. Wheat plants, for example, are 
divided into six different fractions. Each fraction 
contains a leaf and a part of the stem, whereas the 
first fraction contains the ear. The division is 
1. Physiology 
- dry matter 
- pigment content 
- cell-wall constituents 
- crude protein content 
2. Morphology 
- stage of growth 
- stand height 
- plant geometry 
- number of leaves 
- leaf area index 
- leaf area density 
- ground cover 
- weight of beet leaves 
- internal structure of leaves 
- plant diseases 
3. Beet body 
- weight 
- dry matter 
- potassium, sodium, nitrogen,sugar content 
Table 1 : Agronomic parameters