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

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Introduction limited and environmentally friendly cleaning agents need to be used in organic farming. Because of that, input of such toxic substances, so called xenobiotics, to aquatic ecosystems can be neglected. Also, organic farms usually have low external N-fertiliser input, because synthetic N-fertilisers are restricted and import of fodder and manure is limited. The use of raw phosphates instead of highly soluble phosphates which are not allowed directly influences the lower total P-fertiliser input. According to the limitations, it is obvious that risks in N- and P-leaching on organic farms are generally smaller. Considering risk assessment and outputs generated by organic farming, significant positive influence on water protection can be realised (Paulsen et al. 2002). In organic farming, weeds are the most significant production problem (Stopes and Millington 1991; Beveridge and Naylor 1999; Walz 1999; Zinati 2002) and sometimes total crop losses from weeds can occur. One research of the relative frequency of weeds in the period of three years after conversion to organic farming showed that the total number of weed seeds in the soil had increased more than three times from 4,050 m -2 to 17,320 m -2 (Albrecht 2005). Similar research in areas with different levels of fertility showed an increase in viable weed seed numbers ranging from 54-495% at the end of one crop rotation (Turner 2005). Hence, it is obvious that weed control in organic farming could be designated as the most serious task which needs to be solved by means of automation. This fact is confirmed by most research works and by farmers directly involved in production (Yarham and Turner 1992). While in 1985 the EU had 100,310 ha of organic farmland, that number increased up to 1,462,349 ha in 1995, 5,904,481 in 2003 and 6,115,465 in 2005 (EUROSTAT 2007). As high as the numbers may be, the increasing trends in organic farmland area and pesticide use have levelled off over the past five years. The average annual growth rate of certified and policy-supported organic and in-conversion land in the period from 1988-98 was 34%, while from 1993- 98 the annual rate had lowered to an average of 28%. However, in the period 2002-03 organic farmland grew by only 5.4% and estimates of growth for 2003- 04 are only about 3.0% (Lampkin 2003). In the same time pesticide consumption has also stopped growing. 8
1.3 Weed management Introduction Weeds are the natural result of defying nature’s preferences for high species diversity and covered ground. Theoretically, any plant growing in the wrong place at wrong time can be considered as a weed (Parish 1990). The total absence of weeds can be attained only with introduction of herbicides, but the complete removal of weeds may also cause problems. In that case insects have no alternative but to attack the crop itself and there is no suitable cover for predators of crop pests (Altieri and Letourneau 1982). Generally weeds can be divided into two broad categories – annuals and perennials. Annuals germinate from seed each year, grow quickly, mature in one growing season, flower, set seeds and die in less than 12 months. Perennial weeds live more than one year and recover or regrow from dormant stolons, rhizomes or tubers as well as from seed. A soil seedbank present on the field contains a so called “memory of the land”. It has a great influence on the future plant population and reflects the history of soil management and cultivation, not just in the previous season but over many years (Buhler et al. 1997). In the surface soil layer, down to plough depth, weed seedbanks may vary in density from zero to more than one million seeds per square meter. It is confirmed that any cultivation operation will stimulate another flush of weeds to germinate, if huge reserves of weed seeds are present in the soil. Sometimes when the field is “clean” with low level of weeds, where there has been no or limited seeding in the previous season, vertical mixing or inversion of the soil should be avoided as this will bring up un-germinated seeds. Many weed species could be present in the seedbank but usually some species are predominant, comprising 70 to 90% of the total number of seeds. The biggest impact on the seedbank comes from the plants producing seeds within the field, although there are different mechanisms of seeds introduction. Weed seeds remain dormant in the soil until conditions are favourable for germination. Some annual weeds have extremely long living seeds which can survive more 9
Page 1 and 2: Institut für Landtechnik der Rhein
Page 3 and 4: Development of a novel mechatronic
Page 5 and 6: Kurzfassung Entwicklung eines neuar
Page 7 and 8: Acknowledgements Acknowledgements M
Page 9 and 10: Table of contents Table of contents
Page 11 and 12: Glossary of abbreviations and symbo
Page 13 and 14: Symbol Unit Description Mmmax Nm Ma
Page 15 and 16: Symbol Unit Description Glossary of
Page 17: ωold ωout rad s -2 Latest rotatio
Page 20 and 21: Introduction The most frequently us
Page 22 and 23: Introduction application that had p
Page 24 and 25: Introduction be to go from a system
Page 28 and 29: Introduction than 40 years before g
Page 30 and 31: Introduction techniques. It is know
Page 32 and 33: Introduction Sowing and planting al
Page 34 and 35: Introduction Inter-row weeding syst
Page 36 and 37: Introduction 18 Figure 1.3 Inter-ro
Page 38 and 39: State of the art 20 Figure 2.1 a) F
Page 40 and 41: State of the art cylinder rotates a
Page 42 and 43: State of the art 1998). This device
Page 44 and 45: State of the art 26 2.2 Detection o
Page 46 and 47: State of the art The fluorescence s
Page 48 and 49: Definition of the problem and resea
Page 51 and 52: 4 Materials and methods 4.1 Detecti
Page 53 and 54: Materials and methods Figure 4.1 a)
Page 55 and 56: Materials and methods Figure 4.3 a)
Page 57 and 58: 4.1.2 Data acquisition 4.1.2.1 Hard
Page 59 and 60: 4.1.4 Test objects Materials and me
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Page 63 and 64: Materials and methods environments
Page 65 and 66: Materials and methods dimensions ne
Page 67 and 68: Materials and methods (PFM). As the
Page 69 and 70: Materials and methods A command sig
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Page 73: Materials and methods Another tool
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Results and discussion 58 Figure 5.
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Results and discussion objects. Acc
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Results and discussion Plant positi
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Results and discussion Plant positi
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Results and discussion 70 5.1.4 Dis
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Results and discussion Connection b
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Results and discussion 76 5.2.1 Opt
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Results and discussion xmi1 = ( RLA
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Results and discussion With the inv
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Results and discussion 82 Horizonta
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Results and discussion 84 5.2.4 Sel
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Results and discussion 86 5.2.5 Dis
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Results and discussion Conventional
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Results and discussion Since the fi
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Results and discussion To avoid con
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Results and discussion As the size
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Results and discussion 96 5.3.4 Alg
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Results and discussion 98 V = zc( t
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Results and discussion corresponds
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Results and discussion 102 5.3.6 Me
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Results and discussion hoeing accur
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Results and discussion between the
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Results and discussion distance fro
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Results and discussion Distribution
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Results and discussion cuts are ran
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Results and discussion Forward spee
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Results and discussion x [mm] Distr
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Results and discussion The experime
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6 Summary Summary Neither a mechani
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Summary The third part of the work
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7 Conclusions Conclusions The prese
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8 References References Agrios, G.
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References in California's Sacramen
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References Johnson, W C and Mullini
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References Schans, D. v. d. et al.
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List of figures List of figures Fig
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List of figures Figure 5.24 Scheme
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Plant position 9 Appendix Table 9.1
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Plant position Table 9.3 Detection
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Personal data Education About the a
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