At the selected sites, there were mainly only small differences in crop yield between tillage depths, but on two sites with clay soil yield was significantly reduced by increased tillage depth. In an overall trend, increased tillage depth slightly seemed to decrease yield on heavier soils. The reaction of different crops was little affected by tillage depth. Decreasing tillage depth generally increased penetration resistance (approximately double at 10-15 cm depth for shallow discing compared to ploughing) and reduced saturated hydraulic conductivity in the topsoil. Increasing tillage depth from 5-10 cm to 15-20 cm more than doubled the draught requirement. Mean yield for non-inversion tillage was only 1-2 % lower than for mouldboard ploughing, despite a large increase in penetration resistance. There was also a poor correlation between penetration resistance and crop yield relative to mouldboard ploughing. There was no clear interaction between precipitation and tillage treatment in the effect on crop yield.
Overall, on Swedish soils, there seems to be little need for soil loosening in non-inversion tillage. A shallow working depth can be recommended, especially on heavier soils.