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Page 11
interrow hoe blade widths and determining the optimum length of your T hoes . The document is
available from our website in the Four Wheel Hoe section www.physicalweeding.com/fourwheelhoe.
5.1.3.
Attaching the T hoes
The T hoes are in ‘mirror pairs’ i.e., one is for the left side of the hoe and the other for the right see
Figure 2 Figure 7 and Figure 10. It is essential to put the T hoes on the correct side of the machine
otherwise they will not work.
Figure 10. Right and left hand T hoe blades and clamps (left). Mini ridger and clamp (right).
1.2.1
Longitudinal position
As the T hoe blades extend both inside and outside of the frame they can only be positioned between
the wheels. It is essential to leave sufficient space between the front wheel and the hoe blade so that
the wheel does not block the soil travelling over and along the hoe (Figure 11).
1.2.2
Depth
The optimal depth of the T hoe (and any blade hoe) is just below the soil surface, literally a few
millimetres / ¼”. This is because if a weed seedling is cut through the hypocotyl stem (which is the
section between the roots and the cotyledons) it cannot survive. Hoeing deeper results in the weeds’
roots being undercut, rather than the hypocotyl severed, which results in lower weed mortality.
However, clearly the blades will not work when they are out of the soil! So the final depth setting is a
compromise between being shallow as possible, to maximise effectiveness, while as deep as needed to
ensure that the blade always remains in the soil. This can only be determined by using the hoe in the
field and fine tuning the depth. Also the position of the hoes is likely to have to change with changing
soil conditions.
Setting the depth of the T hoes is best done on a smooth flat floor or a ‘set up board’ as described in
section 5.1.1. With the hoe on the flat area loosen the T hoe clamps so that the blades sit flat on the
surface, and then firmly tighten the clamps. This will set the hoes close to or at the optimum depth, as
the hoe will sink slightly when placed on soil compared with a solid floor, which means the hoes will then
be below soil level by the same amount the wheels have sunk. If the hoes need to be deeper than use
laths or thin bars as described in section 5.1.1 to slightly raise the wheels off the surface and then set the
blades while they are flat on the surface. If the blades are too deep then place a thin (e.g., 5 mm / ¼”)
