Cranfield University

Experimental Methods
Depending on the expected soil displacement of a certain treatment and soil condition the
number of fishing hooks was varied by varying the amount of depth locations at which
hooks were placed. The distribution of the fishing hooks with depth is shown in Table 1.
All depths were replicated three times. The rut depth was taken as the surface/highest read-
ing in the following analysis enabling regression lines including the surface.
Table 1: Intended placement depths of fishing hooks for treatments
Treatment Measured Depths (mm) Total Hooks
Sandy Loam, Subsoiled
Tracked Machine with full grain tank (1) 100, 200, 300, 400, 500, 600 18
Wheeled Machine with full grain tank (2) 100, 200, 300, 400, 500, 600 18
Tracked Machine with empty grain tank (3) 150, 250, 350, 450 12
Wheeled Machine with empty grain tank (4) 150, 250, 350, 450 12
Wheeled Machine with high inflation pressure (5) 150, 250, 350, 450 12
Sandy Loam, Shallow Tilled
All treatments (1 – 5) 150, 300, 400 9*5
Clay, Shallow Tilled
All treatments (1 – 5) 100, 200, 300, 400, 500 15*5
After placing the hooks in the soil, their uniform distribution was verified. During this
process additional fishing hooks were added to the treatments at depths shown in Table 2.
Table 2: Depth and amount of additional fishing hooks for uniform distribution in
sandy loam
Treatment Depth (mm) Amount of additional Hooks
Subsoiled 1 600 2
Subsoiled 3 450 2
Subsoiled 4 450 2
Shallow Tilled 1 400 3
The initial distribution over depth for the fishing hooks is shown in Figure 13, Figure 14,
and Figure 15 for the sandy loam subsoiled, shallow tilled and for the clay, respectively. It
shows that they are well distributed, and cover the required depth range.
Ph.D. Thesis Dirk Ansorge (2007)
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