Discs in inter-row soil processing: types and characteristics

The inter-row tool holder machines are used to very effectively work the soil between rows, increasing, at the same time, the working efficiency thanks to the possibility of installing the inter-row tool in combination with another piece of equipment, positioning them on the front and rear; therefore resulting in the significant optimisation of time and resources.

One of the tools that is most used during inter-row soil tillage is the disc that is undoubtedly the most popular tool thanks to the maximum weeding capacity in consideration of the significant turning over of the soil and consequent burying of the plants.

The Sicma discs for inter-row machines are characterised by being composed of adjustable tools that can be

• passive, where the action is carried out by dragging on the soil and
• active, thanks to the drive with hydraulic unit.

The discs differ in two ways:

1.  idle/motorised smooth/toothed profile rounded swivel disc;
2.  flat disc with idle mounted furrow star.

Let's analyse the individual characteristics in greater detail.

Rounded adjustable disc

The rounded disc tools are hemispherical caps with a smooth or toothed profile, with a diameter of 350 mm, whose inclination is adjustable both in the direction of advancement and vertically to facilitate the penetration and mixing of the soil.

In vineyards the action of these discs takes place by digging the soil around the stems of the vines and moving it towards the row: in this way a furrow is created which results in effective mechanical weeding, then completed by the tilling action  of the soil on the surface, which promotes the flow and absorption of water rich in nutrients and fertilisers to the required depth.

The choice of the toothed profile over the smooth one makes it easier to penetrate the soil. In addition, it cuts plant residues more precisely and minimises the smoothing effect on the bottom of the processing.

Idle or motorised disc?

Using the idle disc means being able to work medium-light but also tough soils: sliding over obstacles and limiting structural damage, it can cut weeds horizontally, invert the soil, mixing it and piling it with minimal compaction.

The smooth or toothed idle disc produces trenching with turning over of the soil but leaves a fairly large portion of untilled soil around the stump that may sometimes require manual completion or localised weeding.

However, there are some precautions to be taken when working with the idle disc, such as:

• the forward speed and the inclination angles (25°-35°) are directly related to the necessary force: increasing them increases the power demand as the volume of moved soil increases, with a direct correlation on the degree of refinement of the soil;
• in the case of very clayey soils, the use of smooth discs risks creating a very smooth terrain that creates the conditions for water stagnation;
• if the soil conditions are not optimal for processing and the disc adjustment is not adequate, the latter may not rotate sufficiently to discharge the earth, which would therefore tend to partially accumulate in the front area, reducing its efficiency.

The motorised disc performs work similar to the idle one but more energetically and is particularly useful for tougher and heavily infested soils.

Using the motorised version of the disc has many advantages: it reduces traction from 10 to 75% (in relation to the angle of inclination of the discs and to the number of turns), it produces excellent homogeneity of the work with greater burial and mixing of residues with a smoother flow of soil movement and ultimately is more efficient, requiring a lower dispersion of power generated by the tractor engine and a better penetrating effect into the soil.  This means being able to maintain a constant depth throughout the work.

As the operation of the discs is at a depth of approximately 15 cm, this must be taken into account in the event of the presence of underground drip lines. Furthermore, the discs could encounter difficulties in functioning and less agronomic effectiveness in the presence of obstacles such as stones, surface stumps and other obstructive factors.

Often this type of equipment is fitted on inter-row tools installed on tractors with powers of approximately 60-70 HP and their advancement usually involves a speed range of between 2 and 6 km/h (higher values are recommended to optimise performance of the idle discs).

Furrow star disc

In conclusion, when we refer to a furrow star disc (also called rollhacke) we are talking about a structure consisting of a central body screwed to a rotating flange at the ends of which are arranged dedicated shaped hooks that penetrate into the soil and turn it during advancement movement.

It can be double or triple and can be adjusted vertically and horizontally; depending on the advancement and the inclination assumed, surface incisions can take place, with removal of newly emerged weed shoots.  This action is performed along the edge of the row and in the area being worked in order to also obtain ridging of the soil towards the centre of the row while maintaining a fair degree of humidity.

The furrow star disc has a reduced effectiveness if used alone: ​it is therefore usual to use it combined with a rotary finger weeder. The ideal conditions of use (max 15 cm depth) usually occur on soils that are looser or previously worked with other tools for high speed operations (above 8-9 km/h) allowing movement or containment of the soil moved by other tools.

The Sicma discs

The different types of discs examined can be applied on several Sicma production machines, such as - for example - the inter-row frames in which all types of discs can also be used in combination with other tools including blades, harrows or weeders.

The discs, however, can also be fitted on tillers, both standard and on those equipped with a bed former kit: the pairs of smooth rounded discs (also called conveyors) positioned in front of the tiller and at the side skids open furrows in the soil thus allowing the machine to work at a greater depth.

Finally, the Sicma inter-row machines, thanks to their versatility of use, also allow assembly in the front of the tractor: in this way the operator can connect a machine such as the tiller at the rear and use the relative discs in one or the other, depending on the type of processing to be performed. All this, as is evident, results in greater efficiency in working the land, optimising time and resources.