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Soil Compaction Models<br />

Depth (mm)<br />

0<br />

100<br />

200<br />

300<br />

400<br />

500<br />

600<br />

Displacement (mm)<br />

0 20 40 60 80<br />

Depth (mm)<br />

Ph.D. Thesis Dirk Ansorge (2007)<br />

0<br />

100<br />

200<br />

300<br />

400<br />

500<br />

600<br />

Dispalcement (mm)<br />

116<br />

0 20 40 60 80 100<br />

Figure 80: Predicted vs. measured soil displacement on clay soil in field for � of 4 (- -<br />

-) and 5 (- • -) at normal (2.5 bar) [squares] and high inflation pressure (3.5<br />

bar) [triangles]<br />

6.3.4.2 Sandy Loam Soil<br />

In this section the data from both the sandy loam shallow tilled and subsoiled experiments<br />

will be pooled to gain the slope and intercept of a VCL. The identical procedure as de-<br />

scribed in the previous section was used to gain the slope and intercept of the VCL. In Ap-<br />

pendix 1/1.4.2 a split of the VCL according to the different tillage treatments is provided<br />

showing marginal differences and the DBD profile is given, too.<br />

The resulting VCLs for a � of 4 and 5 are shown in Figure 81. The predicted soil dis-<br />

placement for the VCLs is shown in Figure 82 for the shallow tilled soil. Soil displacement<br />

is larger for a � of 5 compared to a � of 4. Overall a � of 4 fits better in the field, how-<br />

ever, using the VCL created in the soil bin on the same soil type with a � of 5 was found<br />

to fit best. This is due to the fact that the VCL from the soil bin contains more and better<br />

defined data points. The field experiment was conducted at a moisture content of approxi-<br />

mately 20 % while the soil bin experiment was conducted at about 9 %. The good agree-<br />

ment in predicted soil displacement using the soil bin VCL is due to a similar distance<br />

from optimum moisture content for compaction which is at about 15 % moisture content<br />

for a sandy loam soil.

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