Operational Benefits of the RotaDairon® Soil Renovator™

Notes: Bruce Gledhill
Product Manager - RotaDairon South Pacific

1. Minimal damage to soil structure
2. Minimal compaction
3. Least possible panning effect
4. Surface improvement
5. Strata improvement
6. Reduced chemical use
7. Least possible moisture loss
8. Quality seed bed formation
9. Optimal seed strike conditions
10. Extended regrassing season

Soil damage

The tip speed of the RotaDairon® rotor is typically 30-40% less than comparably sized rotary hoes or power harrows therefore the impact rates in the RotaDairon® at the point of contact are less.

The direction of rotation, against the direction of travel means the blades are cutting up from the bottom of the cultivation causing the soil to be ‘broken-out’ and away from the base layer rather than being worked or compressed between the blade and the base layer.

This means that the rotary hoe is hammering exactly perpendicular to the ground level at the point of impact against the whole structure of the base layer. In order to penetrate against this maximum resistance the blade has to exert high point loads that will cause high compressions that give way to give a shattering effect radiating from the point of contact or line of arc.

The forward travel speed relative to the rotor speed is also lower than with comparably sized rotary hoes. Therefore the volume broken-out per revolution of the rotor is greater.

These two effects imply that the rotary hoe has a greater mechanical effect on soil structure in the area of cultivation and a contributing effect on panning tendencies in the base layer by transmission of the downwards action.

Minimal compaction

Compaction is caused by three factors, blade action in a rotary hoe, tractive
effort through the tractor tyres and dynamic load through travel speed.

If the ground is rough and the speed relatively high the dynamic loads generated by large unsprung tractors will be significant. These can only be absorbed by the soil.

Two features of the RotaDairon® imply less compaction of the base layer from a finished cultivation as compared to ‘conventional methods’.

Being a one-pass operation the opportunity for soil compaction from both the tractive effort and the travel speed has to be less than a conventional operation that requires more passes at higher speeds to achieve the finished seedbed.

Working in reverse the RotaDairon® does not produce the deep compressive effect of the rotary hoe blade.

Least possible panning effect

Panning is the extreme result of compressive loads combined with ‘burnishing’ in soils with higher organic or clay contents.

Panning occurs in a distinct band between the base layer and the cultivation and is typified by the soil density increasing with depth, often to the point of hydraulically and mechanically sealing the cultivation from the base layer.

The thickness of this impenetrable layer is dependant on the soil type and the methods used to work it.

The RotaDairon® principle of breaking soil out totally eliminates the prospect of impact loads being applied to the soil and transmitted into the base layer.

This benefit of the RotaDairon® principle can be easily demonstrated by working both types of machine on very hard soils. The hoe will find it difficult to penetrate and will bounce around literally chipping the surface until the operator gives up out of concern for his equipment.

The power harrow will not have any effect. Conversely the RotaDairon® will dig itself smoothly into its full depth and will operate smoothly at a speed that the tractor can maintain appropriate for the ground conditions.

The RotaDairon® blade design is such that it has a leading edge, as do rotary hoes and power harrows but no trailing edge.

This lack of a trailing edge as compared to a hoe blade means that the soil remaining largely undisturbed in the base of the cultivation is not subjected to a wedged compression as the trailing edge wipes in the arc of the cutting edge.

In some rotary hoed soils this can be seen as a hard shiny surface, almost a skin, in the base of the cultivation.

Surface improvement

The RotaDairon® machine, dependant on its size, is able to bury a wide variety of debris, stones, small trees and clumps of vegetation. These are picked up with the freshly broken out soil and thrown relatively gently against the separation screen fingers on the rear of the cultivator.

Fine soil and pebbles pass through the fingers while the large material (+20mm) is trapped within the cultivation chamber and falls down into the cultivation ‘trench’.

Integral in the machine is a grading blade that captures the worked soils after they pass through the fingers. This blade spreads the fresh and graded tilth over the debris that has fallen into the ‘trench’.

In catching the tilth it also accumulates a small volume as the unit travels, this spreads itself evenly across the width of the cultivation and will fill small holes and remove small high spots in paddocks.

While not intended to be used as a grader this slight effect can be managed to improve the paddock contour.

Burying stones, grass clumps etc will also improve the travelling conditions for tractors and machinery allowing higher and more comfortable travel speeds – or historic travel speeds with less dynamic compaction.

Strata improvement

The burying effect is in fact partially a gravity separation, heavier materials fall faster into the ‘trench’.

Large stones will be found in the bottom of the trench, woody material above this and clods next with the tilth in a layer at the surface because it has been able to pass through the fingers.

It is important to note that the RotaDairon® does not beat the clods into tilth rather that the tilth occurs as the soils ‘break-out’ and by abrasion within the machine as the clods tumble over the rotor.

Digging into cultivation in ‘cloddy’ soil it can be seen that the surface is well prepared tilth while the clods are neatly layered below.

Similarly in ground that is 90% stones of varying sizes you will find the cultivation distinctly layered small on top, largest on the bottom.

Placing the debris, both hard and soft, deep in the cultivation provides a ‘base coarse’ for the seedbed. Improved drainage, and better aeration of the soil follows.

Allowing the roots of the grass to penetrate into this ‘base coarse’ provides for a deeper root structure that is more resistant to mechanical stresses, wind and water erosion and that has better access to moisture.

Reduced chemical use

The prospect of reduced chemical use is available where an operator wishes to avoid spraying out a paddock prior to regressing. The RotaDairon® will bury weeds and old grass deep enough that it will decompose and not germinate.

Perhaps more so in vineyards this feature reduces the limits placed on spraying by windy conditions.

Least possible moisture loss

Each time soil is turned over it presents fresh moisture to the elements.

Under conventional cultivation it will take a number of passes to achieve the ideal seedbed. Every pass between the first and the last looses moisture.

When finally the conventional seedbed is ready it has lost the most moisture it can. The seeds are being placed in a situation where more water will probably be required to get a good strike.

Coupled with moisture loss due to repeated cultivations is the idea of heat loss for similar reasons.

With the RotaDairon® combination cultivator-seeder system the ground is prepared into the ideal seedbed with the most moisture the fresh ground will have to offer until the next rain.

Similarly the seeds will be placed into the warmest soil because it had only been turned for a fraction of a second before the seed was placed.

Best possible combination of conditions for germination.

Quality seedbed formation

As discussed in the sections above;

• the tilth has been raised to the surface of the cultivation,
• it is relatively clean of foreign material,
• it is relatively well graded and free of clods,
• the tilth is spread to fill hollows and reduce high spots in the paddock.

Optimal seed strike conditions

The RotaDairon® seedbed is as moist as and as warm as it can be for the seed placement.
The notched cast iron or mesh roller provides the correct degree of compaction to gently bind the soil while the seed germinates and the grass plants establish. It also creates small pockets in the rolled furrows that act both to collect moisture and to create a small heat collector - one turf specialist described this as a ‘micro-climate’ to us on the seedbed.

Extended regrassing season

Simply because the seed bed is sown immediately it is prepared the season is extended a few days, perhaps a couple of weeks depending on the scale of operations and the number of tractors and machines involved.

Likewise during the working season the effect of lost time due to weather is reduced. If you can get back on the ground you can get the seed on that day, not after you have done 2, 3 or 4 passes.

We are also told that the RotaDairon® is less susceptible to being unable to work because of damp soil. This too could extend the productive time in the season.

Quality since 1958