First, let’s clarify the task, as it sets the requirements.
One function of stubble stripping is to create a moisture-stable soil structure. By the end of the growing season, our soil typically settles. While the crop’s microclimate keeps it moist and relatively workable, it dries out, starts to crack, and hardens a few days after harvest. By working the surface shallowly and uniformly, we can control this cracking and water loss.
Shallow mixing and shredding of stubble residues are important preparations for subsequent operations. Firstly, shredding the stalks reduces the risk of clogging for deep tillage tools, and secondly, shallow mulch promotes the decomposition of residues. Under our moisture-stable surface, the deeper layers do not dry out as much, making them easier to work. Lastly, the tillage depth is always proportional to the clod structure size. What we moved during stubble cultivation no longer increases the clod size of deeper tillage.
From the above, it follows that we aim to achieve a shallow, homogeneous, closed mulch layer with a fine clod structure.
A well-proven tool for this is the V-shaped disc harrow. Everyone knows it, and it is available in endless variations, but what makes one good and another useless?
To achieve a fine clod structure, we need to work shallowly. If we go deep right away, the clods will be large, and we will struggle to break them down later. The spacing of the disc blades and the working depth are related; if we want to avoid leaving strips with wider spacing, we need to go deep, which, of course, creates clods. So, it should be dense. BUSA’s medium-heavy discs are equipped with a 225 mm spacing as standard.
It follows from the same that the rear row must be driven at the spacing of the front row of discs. However, the rear row wants to follow the front row, where the resistance is lower, so there is no unworked strip. To solve this, the balance of the two rows of discs must be finely tuned. Since the front row pulls the machine to the left and the rear row to the right, the two create a torque that would cause the machine to start to tail. This is somewhat compensated by the fact that the front row has a greater load, and therefore its force, while the rear row is further from the tractor, so its leverage is greater. Fine tuning is possible by placing the drawbar or regulating the load on the rows of discs.
It is important to emphasize that it is not advisable to operate a V-shaped disc harrow semi-mounted with a drawbar, as the lower lift arms are typically moved by single-acting hydraulic cylinders, making it impossible to load the drawbar downwards, i.e., to change the load on the front or rear disc rows.
With the Busa disc harrows, the load on the two disc rows can be adjusted with a simple movement using the leveler, or a hydraulic leveler can be ordered if needed.
Finally, the closure – If the goal is to preserve moisture, the surface must be compacted. An excellent tool for this is the BUSA spiral angle iron roller, which acts like a wedge roller but, due to its construction, is not sensitive to unevenness and leaves a well-compacted, even surface.If shallow compaction with more intense shredding is needed, the same roller frame can be equipped with lattice breaking rollers, which are ideal for simple seedbed preparation.
Nothing proves the functionality of BUSA discs better than the fact that despite not stripping down our machines due to intense price competition, the demand for our machines remains. The positive references of many old, heavily used machines are a convincing reason not to focus solely on price when buying a new machine.
