Effekter av bearbetningsdjup i plöjningsfri odling
In Sweden, reduced tillage usually means non-inversion tillage, where primary tillage is carried out using chisel ploughs or disc implements. Primary tillage method is mainly determined by the desired soil loosening and the handling of soil residues.
The effect of tillage depth was studied in field experiments in Skåne, Väderstad, Uppsala, Örebro och Västerås in different crops; spring oilseed rape, spring wheat, winter wheat and spring barley.The experiments generally had a randomized block design with the treatments mouldboard ploughing, deep chisel ploughing and shallow chisel ploughing, in some cases also shallow discing and no-tillage. In the experiments the following parameters were determined: seedbed properties, saturated hydraulic conductivity, penetration resistance, number of emerged plants and crop yield (all parameters were not determined in all experiments. Root growth and draught requirement were determined in two separate studies.
There were no significant differences between tillage depths in non-inversion tillage in seedbed properties, plant emergence or root development. Shallow tillage increased penetration resistance and reduced saturated hydraulic conductivity in the upper part of the topsoil. Mouldboard ploughing resulted in the lowest penetration resistance, the highest hydraulic conductivity, the smallest aggregate size in the seedbed and the lowest water content in the seedbed bottom. Crop yield for deep as well as shallow chisel ploughing was 2 % lower than for ploughing, while it was 5 and 16 % lower, respectively, for discing and no-tillage. The results imply that increased tillage depth with a chisel plough does not increase crop yield, while shallow tillage with a disc implement may give poorer soil conditions and reduce crop yield. The low yield for no-tillage can mainly be explained by poor crop establishment.