To ensure optimum conditions for organic cereal growing, it is important to minimize both compaction
and soil inversion depth. The relative effects of using light versus heavier tractors, shallow versus deeper
ploughing and on-land versus in-furrow wheel placement during ploughing were investigated in threeyear
organic rotations dominated by cereals with naturally infested stands of perennial weeds. The second
part of the experiments was carried out in continuous barley with transplanted root fragments of Cirsium
arvense (L.) Scop. and rhizome pieces of Elymus repens (L.) Gould. Ploughing was performed in spring under
favourable weather conditions. Neither tractor weight nor wheel placement influenced decisively the
numbers and above-ground biomass of perennial weeds. Depth of ploughing, on the other hand, affected
both perennial weed infestation and yield levels consistently. Weed numbers and the total above-ground
weed biomass were mostly 50% lower with deep ploughing (25 cm) than with shallow ploughing (15 cm).
The greatest advantage of deep ploughing appeared in the control of C. arvense, which in some cases was
reduced by more than 90% compared to shallow ploughing. In organic rotations dominated by cereals,
therefore, combating of perennial weeds by deep ploughing may be more important than factors such as
tractor weight and wheel placement.