Cranfield University
Cranfield University
Cranfield University
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Field Study With Full Size Combine Harvesters<br />
Figure 62 b) shows the DBD for the experiment on the shallow tilled sandy loam measured<br />
with the Troxler. All runs were significantly higher than the control and there were again<br />
neither significant differences amongst the controls, nor the runs themselves. In absolute<br />
numbers the high inflation pressure tyre experiment caused a 0.004 g/cm 3 higher DBD than<br />
the track experiment. This marginal difference was surprising and as the results of the<br />
Troxler on clay compared to all the previous parameters showed must be caused by the<br />
insensitivity of the method.<br />
The tyre at normal inflation pressure had the smallest DBD after the run. Appart from the<br />
clay data shown in the previous paragraph this was the only time ever, that a tracked ma-<br />
chine caused in tendency more soil compaction than a wheeled machine at normal inflation<br />
pressure. This does not agree with all other measured soil physical parameters.<br />
The measurements taken in the subsoiled sandy loam showed a significant increase from<br />
the control to the measurement taken after the pass of the machinery. There was no signifi-<br />
cant difference between the controls as can be seen in Figure 62 c). It includes the 95 % CI<br />
for the control and the run measurements. The absolute values for the run measurements<br />
showed the same tendency as the fishhook method with the lowest density for the track<br />
experiment followed by the tyre at normal inflation pressure followed by the high inflation<br />
pressure tyre. However, none of these differences were significant.<br />
4.2 Discussion and Conclusion on Field Study<br />
The benefit of the rubber tracked machine in comparison to the wheeled machine was<br />
shown in field on sandy loam and clay soils with respect to reduced rut depth, soil dis-<br />
placement, and penetrometer resistance. This confirmed the findings from the soil bin labo-<br />
ratory and field study from Ansorge (2005, a) and Chapter 3. The average increase in soil<br />
density in the field on both soil types was similar to the one found in the soil bin laboratory<br />
study, but reaching only to a more shallow depth.<br />
The penetrometer resistances did only show differences on the most pronounced case, the<br />
subsoiled sandy loam. On all other occasions the soil was too wet. Interestingly the pene-<br />
trometer resistance on the sandy loam exhibited a similar pattern after the pass of a<br />
wheeled machine on both subsoiled and shallow tilled sandy loam. The tracked machine<br />
Ph.D. Thesis Dirk Ansorge (2007)<br />
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