Agriculture Reference
In-Depth Information
7.3.1.3
Implications for Soil Tilth Sensing
The important prospect is that a tine sensor instead of a sieving method can deliver
signals about soil tilth online and on-the-go. Thus it is possible to react on the
respective site-specifi c situation in real-time. The object of control would be either
the soil
break-up
by the secondary cultivation or the
seed-rate
, assuming that a
higher seed-rate might be needed with a coarser seedbed and
vice versa
. However,
the concept of adjusting the seed-rate to the respective soil break-up is like repairing
a symptom and leaving its cause unaltered. The better approach for most crops
probably is to avoid local defi ciencies in the relative emergence as much as possible.
Hence, controlling the soil break-up on the basis of the tilth sensed is the more logi-
cal procedure.
Where should the sensing-tine take the signals during the cultivation procedures?
It would be possible to take the signals after primary cultivation by placing the
sensing-tine
ahead
of the secondary cultivation implement. With suitable imple-
ments, this would allow to set up a control system for the secondary cultivation on
the basis of the soil break-up by the primary tool. However, in order to get the
desired seedbed, it still would be necessary to know the fi nal soil break-up by the
secondary implement in advance. This knowledge - on a soil specifi c basis - is
hardly available. A simpler and more logical control system ensues if the sensing
tine is placed
behind
the secondary cultivation implement. Thus the effect of the
respective primary- and secondary implement is included in the fi nal control.
However, this position of the sensing-tine would need very fast control results in
order to prevent too late adjustments since the sensing occurs afterwards. A com-
promise between these positions ahead or behind would be to place the sensing tine
within the secondary cultivation tools,
e.g.
within the last row of tines.
The emergence of the seeds depends largely on the water transferred to them
from the soil, therefore on the clod break-up as well as on the water content in the
soil. But knowing the water content at the time of secondary cultivation and sowing
alone is not suffi cient. The short-term water supply in the fi rst days
after
sowing is
the most important criterion for emergence. Because this is so, there is still a huge
lack of certainty when the question of the soil break-up needed for high emergence
comes up. With much rain in the fi rst days after sowing a coarse seedbed suffi ces
and might be even benefi cial, and with dry days after sowing it is
vice versa
.
But the short-term weather forecasts still are not reliable in most parts of the
world. The expectations for reliable rain-forecasts, which were raised since the
introduction of
weather satellites
and of new meteorological techniques, have not
been met. The situation is that the existing uncertainties about short-term weather
prospects bring about one of the biggest problems with many precision farming
operations in rainfed areas. This applies especially to secondary cultivation and
sowing operations. The objectives with the use of a soil tilth tine sensor could be
defi ned much more precisely, if the rainfall in the next few days were known,
because then the soil break-up needed could be defi ned more accurately.
Mapping the results of a tine-sensor would be possible. However, this would be
reasonable only if additional soil properties, which were sensed too, were
