Browsing by Subject "Direktsaat"

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    A study of integrated weed control strategies for establishing soybean (Glycine max L. MERR.) in the German production system
    (2017) Weber, Jonas Felix; Gerhards, Roland
    Soybean (Glycine max L. MERR.) has expanded to become one of the most traded agriculture products worldwide in recent decades. Europe is one of the primary importing regions; however, the dependence on soybean imports has been critically assessed by the public. To reduce the dependency on soybean imports, increased local soybean production should be favoured. In addition to environmental conditions, weeds are a major limiting factor for soybean yield under German climate conditions. Weeds can be successfully controlled with herbicides, although crop injury frequently occurs after application. Sensor-based screening would be helpful for a rapid evaluation of cultivar tolerance to herbicide application. Alternatively, mechanical weed control strategies can be applied. Since soybean production is currently introduced to the regional crop production, weed control efficiency of conventional mechanical tools (e.g., hoeing and harrowing) have to be evaluated. By using automatic guiding systems intra-row elements could be utilised to increase the weed control efficiency of mechanical hoeing. Other than that, agronomical practices such as the tillage system or cover crops influences the occurrence of weeds. The most common practise worldwide for soybean cultivation is the no-tillage system, which has not yet been investigated under local conditions. Therefore, different weed control strategies in soybean production were investigated according to the following major objectives of this thesis: - Detection of crop injury by herbicides using a chlorophyll fluorescence imaging sensor for different soybean cultivars. - Evaluation of the conventional mechanical strategies of hoeing and harrowing in soybean. - Examination of the weed control efficiency in inter- and intra-row areas using RTK-GNSS precision steering and an optical camera guiding system for mechanical weed control in soybean. - Evaluation of the efficiency of ‘tillage’, ‘reduced tillage’ and ‘no- tillage’ cultivation systems and the influence of cover crops on weed suppression in local soybean production. The Imaging-PAM-sensor based on chlorophyll fluorescence imaging was utilised to investigate the response of different soybean cultivars to the application of herbicides. The measurements indicated significant differences with respect to injury to the cultivars after herbicide application. Herbicides containing the active ingredient ‘metribuzin’ resulted in significant differences in the level of crop injury depending on the cultivar. The active ingredients ‘dimethenamid’ and ‘clomazone’ resulted in less injury, independent of the cultivar. The PAM-sensor was able to detect stress symptoms 3 to 7 days before visual symptoms appeared. An investigation of hoeing and harrowing, which are conventional mechanical techniques for weed control, showed 78% and 72% weed control efficiency, respectively. In further experiments, the results of precision steering systems using RTK-GNSS and an optical camera guiding system additionally equipped with intra-row elements (e.g., finger weeders) were compared with the results of conventional hoeing. Mechanical weed control using automatic steering technology and an intra-row element (finger weeder) reduced the weed density by 89% compared with 68% in the conventional hoeing system. With respect to crop yields, statistical benefits of precision steering were not observed. However, the driving speed could be increased from 4 km h−1 in the conventional hoeing system to 10 km h−1 using the automatic steering systems. In an additional experiment, two cover crops species, rye (Secale cereale L.) and barley (Hordeum vulgare L.), were grown for preventive weed control in soybean production. The cover crops were transformed into a mulch layer using a roller-crimper immediately before soybean was sown using a no-tillage technique. Conventional tillage was performed to compare the systems with respect to their weed control efficiency, crop development and soybean yield. The results showed that the no-tillage system had a greater effect on suppressing summer annual weed species (Chenopodium album (L.), Echinochloa crus-galli (L.) P. Beauv. and Amaranthus retroflexus (L.)) than the tillage systems. Conventional tillage and reduced tillage showed increased suppression of the weed species Matricaria inodora (L.), Stellaria media (L.) Vill. and Sonchus arvensis (L.), which were present in the no-tillage system. However, in the conventional tillage and reduced tillage systems, an additional weed control treatment was necessary to suppress the summer annual weeds and ensure high yields. The cover crop rye resulted in weed control similar to that of barley in the no-tillage system. Despite the low weed density, the no-tillage system with a rolled cover crop showed a yield reduced of 47%, whereas the yield of the reduced tillage system was decrease by 23% compared with the conventional tillage system.
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    Modelling and optimisation of no-till seeder dynamics for precise seeding depth
    (2019) Sharipov, Galibjon; Griepentrog, Hans
    Achieving better seeding depth consistency in no-till seeding is a critical performance metric of the seeding machine and is of great importance due to its profound effect on reliable seed germination and seedling emergence resulting in a yield increase. Growing implementation of no-tillage in big size farms requires high-capacity seeding machines with increased operation speed and working width. Thus, the increased capacity of the seeding machine as well as harsh soil conditions like the surface undulations and the presence of previous crop residues make the desired working quality of no-till seeders challenging for both designers and manufacturers. The aim of this cumulative dissertation was to optimise a no-till seeder dynamics in terms of vertical motion stability for better seed placement under realistic high-capacity performance. To fulfil this aim, an approach to achieve the desired dynamic behaviour of the seeder was carried out based on three phases: (1) evaluation of the seeder dynamic performance by defining the relationship between the seeder dynamics and the corresponding seeding depth variation, (2) modelling and simulation of the seeding assembly motion dynamics to specify a control system (e.g. MR damper system) for dynamics improvement, (3) implementation of the defined system into the seeding assembly and testing of the new seeding assembly prototype. The present work was the first approach to optimise the dynamic motion behaviour of a no-till seeder by implementing an MR damper system into its seeding assembly for better seed placement under realistic high-capacity working conditions. The AMAZONEN no-till direct seeder was an ideal candidate for this investigation as it contains 12 identical tine type seeding assemblies where the operating depth is defined by the position of the packer wheel. Under working conditions, the maximum width is 3 m resulted from the inter-row distance of 0.25 m between the seeding assemblies. The seeding assemblies are provided with downforces using a hydraulic cylinder in order to keep the packer wheel of the assemblies on the ground and to maintain a consistent seeding depth during seeding operation. Concurrent and geo-referenced sensor data made it possible to acquire the dynamics parameters of the seeder and the corresponding soil surface profiles (the point where the packer wheel touches the ground). This together with the measured 3D geo-referenced position of the seeds gave the opportunity to define the reason of high variations in seeding depth. A sensor-frame was developed, utilising up-to-date sensor technology, to capture the seeder dynamics and to determine the corresponding soil surface profile. A combination of strains recorded at the three corresponding points of the seeding assembly using linear strain gauges was employed to calculate the vertical forces, draught forces and the profile impact forces. A new methodology was introduced to extract the absolute seeding depth from the combination of the determined surface profile and the measured 3D position of the seeds in absolute coordinates. Geo-referenced coordinates of seed positions in combination with geo-referenced surface profile and machine dynamics parameters, offered the possibility to define the reason of seeding depth variation. To do that, the relation between the forces (i.e. vertical and profile impact forces) and the variation of seeding depth was defined by correlating the spatial frequency contents of each dataset. An investigation of the seeder dynamics was carried out by modelling and simulating its performance based on measured data (e.g. determined surface profile and vertical forces) to define a system that can reduce the effect of the forces for better seed placement in no-till seeding. The seeding assembly together with and without a MR (magnetorheological) damper system, which was considered to be located in-between the coulter and the packer wheel, was introduced as a semi-active and passive system. Furthermore, three hysteresis models, such as Bingham, Dahl and Bounc-Wen model, were applied for the semi-active MR damper system behaviour. Among the models, the Bouc-Wen model demonstrated more significant improvements over the passive system model. Analysis of the performance of the semi-active MR damper implemented seeding assembly against the passive system proved the vertical motion dynamics of the assembly, in terms of vertical displacements (52.3%) and its affecting forces (54.1%) to be optimised for better seed placement. Testing the performance of the MR damper implemented seeding assembly compared with that of the original seeding assembly confirmed the potential of the MR damper implemented seeding assembly. The dynamics of the seeding assembly with the MR damper depicted a reduction of 67.69% in the amplitude of the impact forces compared to the original seeding assembly. Consequently, the improvement in the dynamics resulted in better seed placement. The variation of the damped seeding depth, as it was the performance of the seeding assembly with the MR damper, compared to the target seeding depth resulted in an absolute error of 11.9 mm for 95% of its samples, which is considerably less than the error with a value of 21.3 mm for the seeding depth variation resulted from the original seeding assembly. By designing the seeding assembly with the MR damper system, the dynamics of seeding machine can be significantly optimized for better seeding depth consistency.