Mitigation of subsoil recompaction by light traffic and on-land ploughing. II: Root and yield response

Plough pans have been shown to severely hamper root development, limit rooting depth and reduce crop yields. We evaluated the effect of plough pan compaction on root and yield response for a winter wheat in a field trial conducted in two neighbouring fields (B3 and B4) on a sandy loam. Plots were mechanically loosened to a depth of 35 cm in 1997 (B3 and B4) and again in 1998 (only B4). Perennial grass/clover was grown with limited traffic intensity in 1998-1999 and 1999-2000 for B3 and B4, respectively. The perennial grass/clover was ploughed under in spring 2000 (B3) and spring 2001 (B4) and oats established. After harvest of oats, winter wheat was established. Recompaction treatments were applied to the mechanically loosened plots in 2000 and 2000+2001 for B3 and B4, respectively. On-land ploughing was compared with traditional mouldboard ploughing with the tractor wheels in the furrow. In addition, the loosened plots were either heavy trafficked (10-18 Mg axle load and ~200 kPa inflation pressure) or light trafficked (<6 Mg axle load and