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.