Mechanical weed control methods
Mechanical weed control and stubble cultivation methods can be used even before a crop is actually sown. Ploughs and cultivators are both good options for large-scale cultivation. Weed removal is absolutely critical for creating optimum conditions for the main crop and ensuring good yields. Nevertheless, mistakes can be made during seedbed preparation that encourage weed infestation and require additional measures to be taken. Over the past century, more and more chemical alternatives have been used in addition to the various mechanical methods of weed control. Chemical plant protection products became widely accepted because they are easy and cheap to apply. They have, however, come under increasing criticism, which has led to a search for alternatives. Applying plant protection products incorrectly or too often can also cause weed resistance, which makes it difficult to control weeds. What is more, mechanical weed control seems to be the only option for organic farming and vegetable cultivation due to the requirements that exist in this sector. Frequent ploughing has a negative impact on the soil structure, which is why using water-saving min-till methods makes sense. Disadvantage: it can lead to increased weed infestation in the field. The large-scale mechanical cultivation of arable land is relatively simple before sowing, but becomes harder once the main crop has germinated. This is because greater precision is required after sowing and crop emergence compared to during the seedbed preparation stage. There are various ways to approach this and we will cover them in the next section.
Hoeing and harrowing
There are three scenarios for mechanical weed control once the main crop has germinated: between the rows, in the rows and on the surface.
Hoes and ploughs work between the crop rows. Ploughs are used to form ridges and should cover unwanted weeds in the rows with soil in order to hinder their growth. This approach is often seen in maize production. Hoeing implements, on the other hand, remove the weeds from the soil in between the rows. The uprooted plants lying on the surface dry out in the warm weather and die off. For good results, the hoeing elements must run closely alongside the plants of the main crop. Without automatic guidance, you need to have a clear view of the blades. Otherwise, it is impossible to guide the vehicle precisely.
Special tools such as torsion weeders can be used to control weeds mechanically within the rows. These consist of spring tines that move within the rows. The tines are deflected from the main crop and only remove unwanted growth from between the plants. As such, this method of mechanical weed control can only be used on stable, established crops. Finger weeders, on the other hand, work in a similar way to a disc harrow; the main difference being that they consist of multiple individual fingers that press into the soil between the plants and uproot and remove the weeds.
Harrows are more suited to large-scale weed control.. They often consist of multiple individual spring tines that are dragged over the crop. When used correctly, the established plants from the main crop are not damaged in the process and remain in the ground. Weeds, on the other hand, are uprooted and removed. Positive side effect: it encourages tillering in cereal crops. When harrowing, the soil should be loose and free flowing, and the weather dry and sunny. But even mechanical weed control cannot do everything. Tine harrows, for example, have virtually no effect on crusted soils. There is also an increased risk of frost damage after mechanical weed control. Furthermore, it is difficult to use within the row and especially on established weeds.
Mechanical weed control and precision farming
Since a great deal of precision is required during mechanical weed control, technical precision farming methods exist to support this type of work. For example, automatic steering systems keep the equipment on track by using GPS data. When using these systems, it makes sense to use the same machine routes for both sowing and mechanical plant protection. A suitable field planning application enables you to optimally coordinate consecutive work steps. Targeted action between the rows depends on the GPS signal. That is why farmers use real-time kinematic (RTK) technology for greater accuracy. Lumps and bumps on the field surface create additional hurdles which can knock implement tools out of alignment. Enhanced precision can also be achieved by using sensors. Sensors analyse the crops and guide the blades closely alongside the main crop. This accurately removes unwanted growth. In addition to sensors that detect rows, there are some that also identify different plant species. Plant identification apps have been available on the market for quite a while now. As farming processes become more robotised, the strengths of these apps can be used more frequently for mechanical weed control. However, it will be a while before fully autonomous machines such as robots become widely used in farming. ‘Concept vehicles’, on the other hand, are already being tested on selected trial fields.
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