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

Introduction
Optimal organic systems need to include the following levels in descending
order (Merfield 2000):
� crop rotation;
� soil structure, nutrient ratio and pH value;
� crop choice;
� cultivation;
� sowing, planting and related techniques;
� crop production techniques;;
� physical (mechanical or thermal) weed control and
� hand weeding (if necessary).
There are actually two main methods of weed control: indirect weed control,
which is concentrated to improve competitive advantages of the crop over the
weeds using cultural or management techniques, and direct weed control,
where the weeds are suppressed or eliminated by physical interaction.
1.4.1 Indirect weed control
Crop rotation is an essential foundation of organic production, because the
introduction of different crop ecosystems on the same field prevents the
domination of one ecosystem. According to the different crop habits, timing of
production and cultivation requirements, the growing of different crops in
succession ensures, that no weed species can become dominant (Lockhart et
al., 1990). Oppositely, the continuous production of similar crops on the same
place will often significantly increase the population of problem weeds.
An important perspective in organic weed management is to ensure well
balanced nutrient ratio and pH value, although it is not the most important
factor. If soil nutrient ratio and pH value are suboptimal, they can become the
overriding cause of a weed problem and decrease the impact of other weeding
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