In this paper we present the results of a 4-year study on two
contrasting soils of the effects of tractor weight, ploughing depth
and wheel placement during spring ploughing under favourable
soil moisture conditions. Effects on soil structure, earthworm
populations, crop yields and weed infestation have been measured.
The study included results for organic cereals grown in rotation
with green manure crops and for barley grown conventionally with
a moderate input of mineral fertilizer