direction there is a ground moraine plateau with local diapirs of
sand at domes. Here loamy underlaid sands are encountered that
are partly slack or ground water influenced and have a different
top sand layer thickness (fig. 3). The usable water capacity of the
soil up to lm under field is at most 160 mm, because of the
strongly changing thickness of sand the soil moisture regime as a
whole is a decisive yield factor. The considerable heterogenity of
the soil features in the test area is expected to give a
remarkable time-spatial differentiation in yield formation of the
agricultural crops.
On two days during the experiment airborne radiometer missions
with six lines per flight were conducted. During the period of the
measuring dates there was dry weather, the moisture of the upper
soil layers measured at a total of 32 ground control points
decreased of 2 - 5 % (fig. 3). At noon the temperature of the
upper soil which on the first date was still at 25°C on the
average had increased to about 30°C on the second date. The
vegetation too faced shortage of water, the plant moisture
decreased of 4 18%, the temperature of the leaf surfaces
increased from 17°C to 23°C on the average. In part however these
changes can also be deduced by the process of beginning
senescence .
In the measurement profile the Havel channel was first stressed
significantly with brightness temperatures of 180 K. Important
vegetation areas were a small forest, a field of sugar beets as
well as rows of trees along the road and field path. Corn and
grassland for the given microwave band is opaque, so a differen
tiation of soil moisture over these fields was not expected. The
microwave signal, however, shows a different increase of the
brightness temperature during the time of both dates indicating
the decrease of moisture on major parts of the test sites
investigated (fig3). Areal extrapolation made from the flight
lines showed only some areas near the channel with a exceptional
behaviour .
The decrease of the brightnes temperature indicating an increase
of moisture for plot 570 (sugar beets) can be explained by the
stepping plant growth considering the sugar beet plant structure
