Soil compaction and the growth of vining peas

SUMMARY The effects of differing soil conditions at two sites on the growth of vining peas are described. The work was carried out over several seasons having contrasting rainfall at the time of crop emergence. Topsoil compaction induced by tractor wheelings reduced plant population and yield of vining peas by up to 70%. On the compacted plots peas were unable to compensate for the low population which was demonstrated by the inclusion of a non‐compacted treatment thinned to the same population as the compacted plots. The severity of compaction was greatest when soil conditions were dry at emergence and least severe when wet. It is suggested that compaction resulted in increased ethylene production in the root and shoot tissues and this may be a causal agent of the observed growth modifications. Recultivation of a compacted seed bed prior to sowing resulted in better establishment and higher yields than with the topsoil compacted but final yields were variable when compared to a ploughed control. Double digging did not increase yield above a ploughed control. In one year a 25% yield reduction was attributed to this treatment. The reasons for the reduction in yield are complex but it is suggested that the causal agent was modfied soil and plant water relations resulting in altered crop physiology. Tramlining the crop reduced yield in one year but when the frequency of wheeling damage is considered they would be unlikely to affect productivity.