Development of a novel mechatronic system for mechanical weed ...

Introduction
Sowing and planting also have an indirect impact on weed control and they
could cause problems later on, if suitable attention is not given to them. Sowing
needs to be done in a time when conditions are optimal for crop and suboptimal
for weeds (when that is feasible), to provide rapid germination and overgrowing
of weeds as fast as possible. For many crops, such as legumes and cereals, a
5% to 15% increase in the sowing rate can significantly improve their
competitiveness (Welsh et al. 2002). In row crops, adequately chosen
standardised single inter-row space for most or all of the crops on one farm can
provide considerable benefits. The loss of yield due to standardised row
spacing is more than compensated by the decrease in field operation because
the adjustment of the tools and equipment for different row spacing take a
considerable time. Sometimes, the time necessary for adjustment can take as
long as the fieldwork. Hence, the tolerance for setting up inter-row weeding
equipment in relation to the sowing equipment should be less than 1 cm, which
allows tillage in the same or opposite direction as the crop was drilled.
Crop production techniques, including irrigation and harvesting variation, can
have secondary effects that can improve or worsen weed management.
Different irrigation approaches have a considerable impact on the weed
population. Precise drip and trickle systems or buried drip tapes can result in
much lower weed germination compared to alternatives, such as over head
sprinklers.
If weeds are not eliminated during the harvesting operation, it is very important
to kill them as soon as possible after harvest, to minimise further production of
seeds. One possible solution is use of modified harvesting machines with
additional equipment able to collect the weed seeds after they had been
separated from grain and chaff (Patterson and Bufton 1986). The same
procedure can be done with a static off site seed cleaning unit, to separate crop
from weed seeds, if the harvester separates just the chaff from the seeds. This
technique can drastically decrease the weed population.
14
1.4.2 Direct weed control
Direct weed control encompasses all methods in which direct interaction
between the used tool and weeds are present. Direct methods could be roughly