Deep loosening of clay loam subsoil in a moist climate and some effect of traffic management

Two experiments on the same site in different years compared the effects of different intensities of deep loosening on soil properties and crop yield. Both experiments included subsoiling and one experiment, with potatoes, also included double digging and a comparison of conventional and zero traffic. The site was in a moist climate area (S.E. Scotland) on an imperfectly drained Gleysol with a clay loam subsoil. Cone resistance, soil water content and potential, bulk density and crop yield were measured to assess the effects of the treatments. Subsoiling did not loosen the soil very effectively because the subsoil was wetter than the plastic limit at the time of cultivation, even though the growing season prior to subsoiling was drier than average in both years. Double digging was more effective than subsoiling. Zero traffic gave a large yield benefit, especially when combined with double digging. There was no crop response to deep loosening in the presence of conventional traffic. Deep loosening had little effect on the drainage status of the topsoil.