Detail view

Here is a summary.

When HORSCH first launched the heavy cultivator Tiger AS in 2002, it caused a little revolution. The cultivator was aggressively promoted as a replacement for the plough. The arguments of the manufacturer were a working depth comparable to that of a plough and an excellent working quality. The horse power requirement, however, was comparatively high. Thus, the Tiger AS was not suitable for all farms – for locations with light soils the tine spacing normally does not have to be as narrow as for locations with heavy soils. There are two reasons: first of all, due to the lower yields there are less organic residues that have to be incorporated. And second, soils that contain much sand more often demand a deep loosening due to their natural compaction. In these cases, wide tine spacing’s that require less horsepower are sufficient.

HORSCH responded to these challenges. Today the company offers 4 Tiger models three of which – the Tiger AS, LT and MT - have been compared by the dlz agrarmagazin. The editors wanted to know what influence the tool arrangement has on horsepower requirement and tillage quality. We had the 4 metre versions of the Tigers AS and MT at our disposal, for the Tiger LT we tested the smallest available version with a working width of 4.8 metre. Thus, the values that were determined for the tractive power have been converted for one metre working width. The fourth Tiger, the XL model, has been left out. It only has the name in common with the three other models and is designed as a shallow cultivator.

The test

The comparison was carried out near Schwandorf at the beginning of August. The field we had at our disposal was a harvested winter barley plot with 34 soil points (sandy loam and sandy clay). The straw had been left on the field and had been chopped by the combine however the spread of straw had not been ideal because of the wet weather at the time of the harvest. This has been taken into account for the analysis as far as possible. In total, the chopping quality was extremely poor. In general, the numerous excessively long stubbles could only be incorporated with difficulties under the test conditions.

It rained the day before the test so the soil and the straw on it were wet. Thus, the editors assumed right from the beginning that the incorporation of the straw would be less effective than under dry conditions. Wet, cohesive soils crumble poorly, thus, a good mixing of straw and soil is no longer possible. All three Tiger models have been tested at three working depths – 20, 25 and 30 centimetres – at two speeds each at a working depth of 20 centimetres the dlz testers used the Tiger LT with and without wings to see how the wings affect the straw incorporation. The remaining versions were only tested without wings.

With the Tiger MT, the technical experts made additional tests with a more shallow adjustment of the incorporating discs. Only 80-mm wide MulchMix points were used for all models to get comparable results. The test drivers avoided overlapping.

Before each test run the working depth was carefully set to the stipulated figure. Therefore, for all three Tiger models the aluminium clips at the lifting cylinders had to be changed and, additionally, the height of the lower links of the tractor had to be adjusted. The tractor used was a Challenger MT765C with 261 kW / 355 hp. At a working depth of 30 centimetres the Tiger MT was not able to reach the second speed requirement of 10 km/h. In this case, we worked with the maximum possible speed of 9.5 km/h instead. The electro hydraulic hitch control (EHR) was set to 100 per cent position control to avoid a corruption of the measured values due to a lifting of the lower links.

Complex data collection

To detect the horsepower requirement the test drivers used a traverse that was specially made for this purpose. This traverse had 8 weak spots and several strain gauges. Thus the tractive powers and supporting forces could be determined. The test frequency was 300 Hertz – this amounts to 100 measured values per running meter at a speed of 10 km/h.

The data collection for the incorporation is more complex. For this purpose a soil profile was excavated for each test version and each rerun and the estimated values for the incorporation were noted in a 4 x 4 centimetre box according to the grid pattern method. The result was a total of about 7,000 values that were then analyzed for the versions.

Conclusion

As expected the horsepower requirement was lowest for the Tiger LT. All in all it incorporates the fewest harvest residues – apart from the version with attached wings. If the Tiger LT is used for removing much straw from the soil surface, it should be equipped with wings for shallow and medium deep cultivation. The Tiger AS with ist narrow tine spacing has the lowest horsepower requirement – a fact that considerably affects fuel consumption. The Tiger MT is ranking in the middle. It is the only one of the three Tiger that requires only a little bit more horsepower when increasing the working depth.

Incorporation: At least at a working depth of 20 centimetres the wings of the Tiger LT improve the incorporation. This is mostly similar for the Tiger AS. The better incorporation with wings at the Tiger LT, however, causes an increase of horsepower requirement by 15 per cent. Thus, the wings should be dismantled in general when the working depth is deeper than 20 centimetres. At a working depth of 20 centimetres the Tiger MT leaves a very good optical impression as straw and soil are mixed perfectly due to the discs. When the tines are working deeper, the Tiger MT, however, does not incorporate more material to such an extent as it is the case with the Tigers LT and AS. When adjusting the machine, you have to pay attention to the fact that the tines always run deeper than the discs – at least 10 centimetres. If there is any sideways drift, it can be remedied by having the two disc rows working at different working depths.

The best incorporation – except for a working depth of 20 centimetres – was achieved with the Tiger AS. Thus, it lives up to its reputation as an ideal model for farms with high yields. Here it is possible that the increased horsepower requirement pays off, especially if the plough is abandoned - as due to the better incorporation of straw emergence can be increased and the follow up costs for plant protection can be reduced.