Browsing by Person "Bucher, Ulrich Paul"

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Entwicklung einer selektiv arbeitenden Reihenhackmaschine mit elektrisch angetriebenem Werkzeug zur Unkrautregulierung im ökologischen Zuckerrübenanbau
(2018) Bucher, Ulrich Paul; Köller, Karlheinz
Weed control within the planted rows continues to present a major challenge to organic sugar beet farmers. As sugar beet is very susceptible to competition from weeds during its early development, it is essential that farmers ensure that the soil is kept weed-free until row closure. Mechanical hoeing is available for the soil between the rows, but often only manual hoeing can be used for weed control within the row, with the exception of a small number of non-selective row hoeing techniques. Depending on the level of weed infestation in the field, its use can fluctuate within a range of 60 to 340 Akh/ha. A project for the development of a selectively working row hoeing machine was jointly started in 2009 at Universität Hohenheim with the Baden-Wuerttemberg Ministry for Nutrition and Rural Affairs, the Association of Baden-Wuerttemberg Sugar Beet Growers and Schmotzer, based in Bad Windsheim, to support organic sugar beet cultivation. The project was based on a single-row hoeing machine prototype from a previous project, which already had an image processing algorithm for the selection and positioning of sugar beets. There were also two tool shapes for weed control within a row of sugar beets. These hoeing tools were powered by a hydraulic motor, the speed of which was regulated by a PWM solenoid valve based on driving speed and image processing. Field tests were carried out with both at the start of the follow-on project, and a new design of hoeing tool was also tested. The quality of work performed by the three tools was then compared. The extent of the worked and unworked area within a simulated row of sugar beets was examined, among other aspects, and the method of operation and susceptibility of the tool to becoming blocked when it met larger weeds were also assessed. A mobile electric high-voltage drive was also designed with Ludwigsburg-based Jetter AG, in parallel to the field experiments, in view of problems experienced with the control dynamics of the hydraulic drive. Field experiments were then conducted with the advanced prototype under practical conditions on two test sites in Hohenheim during the following vegetation period. The row hoeing machine was compared with various methods, including manual hoeing combined with a standard hoeing machine for the soil between the rows, and also compared to the results achieved by using conventional chemical weed control. Following the initial practical experiments and the findings obtained from them, the row hoeing machine was further revised and a second row was added. The field experiments were then repeated in the same arrangement as in the previous year, again at two sites, using this two-row hoeing machine. After a two-year long test phase, it is clear that the use of a selectively working row hoeing machine reduces manual work by up to 40 %, depending on the extent of the weeds. Manual weed control continues to be indispensable for removing weeds in the immediate vicinity of the sugar beet plants, which can have an adverse impact on the yield if not removed. Furthermore, the use of the row hoeing machine leads to an unavoidable loss of plants, which, to a certain extent, neither affects the technical quality nor overall harvest of the sugar beets. In contrast, later weeding after row closure can cause significant loss of yield. In conclusion, it is worth mentioning that image processing reaches its limits under difficult conditions of up to 400 weeds per m2. The image processing algorithm also requires further improvement. By contrast, the mobile electrical high-voltage drive and the continuously moving shape of the hoeing tool both fulfill all requirements. Future developments should focus on the further improvement and optimisation of plant recognition and thus the differentiation between cultivated plants and weeds and their position in front of the hoeing machine. The working speed could be increased to more than 3.6 km/h with a faster and more precise image processing method, and damage to plants, or even loss of sugar beet plants, could then be prevented or minimised.