Hot on the heals of the Harper Adams conference exploring the effect of tyre inflation pressure on yields, comes confIrmation from Denmark that softer tyres can boost yields.
The NDI Group is a company specialising in supplying tyres and wheel rims for a broad range of applications, including tractors and agricultural machinery.
Joint research project
Last year it collaborated with the Danish research company, SEGES, to investigate the effect of VF (very high flexion) tyres on yields in maize.
The research was part of a larger experiment investigating the relationship between slurry and seed placement, and to what extent various pre-application treatments of the slurry had, on overall crop yields.
The two companies compared a tractor and slurry tanker running on two sets of tyres. The first had conventional tyres with a pressure of between 2.2 and 3 bar.
The second set comprised VF tires from Alliance with a pressure of 1 bar – Alliance Tyres being a subsidiary of The Yokohama Rubber Company.
The work was carried out on ground which comprised a rough clay-mixed sandy soil which, in Denmark, is categorised as a “JB3” soil according to the Danish soil categorisation system.
Now proven in Denmark
According to NDI this is the first time that such a trial had been carried out in the country and the results were very encouraging.
They show that it is possible to increase the yield of maize between 1.5% and 2.2%, depending on the width of the slurry spreader being used.
In this trial, two widths were chosen, 6m and 9m, with the maize itself being planted in 75cm rows.
Spreading at the narrower width obviously increases the area of the ground over which the spreader would travel, therefore the potential savings would be greater if it could be shown that reducing compaction favoured yield.
Positive results with softer tyres
It was found that there was indeed a positive correlation between reduced tyre pressure and an increase in yield. The results were then plotted to show the anticipated benefit in monetary terms.
For the equipment being used, an expected increase of earnings of €21.80/ha and €32/ha depending on whether it was an 8eight or 12-row slurry injector.
From this graph, the point at which the extra yield pays for the capital expenditure required to move over to VF tyres and rims could be determined. This cost will depend on the wheel size of the tanker concerned.
Perfect ground conditions
It should be noted that these benefits were found even though the slurry was spread in late April while the ground was dry and driving conditions were described as ‘optimal’.
It might be expected that a greater advantage might be found in wetter conditions where soil might be more easily damaged by heavy machinery.
In addition to the benefits of reduced ground pressure, the experiment showed that VF tires reduced wheel slip by 4.4%, which will should lead to fuel savings and preserve soil structure at the field surface.