Agriculture Reference
In-Depth Information
located again at seeding time. An auto-steering function is set for seed placement
precisely between the rows of the previous crop.
In case the field in not flat, it can be necessary to use a control system that is not
solely based on the position of the tractor, because on side-hills or contours the
implement can drift sidewards. To prevent inaccuracies resulting from this, the posi-
tioning control system has to auto-steer the implement as well. This is state of the art.
The same seeding machine and the same track direction should be used year after
year. Because this ensures that small inaccuracies in the lateral opener spacings occur
subsequently in all crops and tracks in the same pattern and hence hardly affect the
result. It is obvious that the best results with this method are obtained if the straw is
harvested as well as the grain.
Inter-row sowing is used successfully in Australia for wheat, canola (rape) and
lentils in no-till rotations with row spacings of 22 cm or more (McCallum
2007
).
A special advantage of this method is the lower incidence of the take-all fungal
disease (
Gaeumannomyces graminis
) in cereal rotations. This probably can be
explained by some
spatial separation
of the seedlings from infections on roots of
the previous crop. And due to less straw being next to the emerged seedlings than
with other no-till sowing methods, the efficacy of soil applied herbicides near the
seedlings might be improved. This holds for the use of row-cleaners as well.
Yet inter-row sowing and row cleaning differ in their response to
long stubbles
.
Inter-row sowing between long stubbles is no problem as long as the vertical clear-
ance of the machinery allows for this. In contrast to this, row cleaners operate better
in residues that are not attached to the soil any more. With long, bulky residues the
best solution for work without interference can be using both inter-row sowing and
row-cleaning (Fig.
8.11
, right).
8.4.2
Seeding into Cover Crops
In humid areas, cover crops can provide for the preservation of soil fertility and for
the suppression of weeds between the growing periods of main crops. Yet no-till
sowing into fields with cover crops presents special problems. At seeding time, the
cover crop might be still growing and might have a dense canopy. Therefore, inter-
row sowing is not possible. And cover crops also complicate the use of row-cleaners,
because the
standing, dense residues
easily get caught in the moving parts of the
machines and thus cause clogging.
Torbert et al. (
2007
) developed an attachment to the front of row-cleaners of
seeder units that pushes the standing, killed residues of cover crops in a forward and
sideward direction. In this way they prevented clogging.
The use of
roller-crimpers
for coping with the clogging problem for no-till
sowing into cover crops originated in Brazil, Argentina and Paraguay (Derpsch
1998
; Kornecki et al.
2009
). This method for sowing into cover crops relies on the
concept that the position of the residue plants - that still are anchored to the soil -
should be in the
direction of travel
of the seeding implements. No hair-pinning of
residues on parts of the seeding implements can occur if the position of the stems
