My research focuses on soil management effects on soil structure and plant growth, with a particular area of emphasis on 1) Soil fragmentation and friability, 2) Influence of soil structure on root growth 3) management effects on soil quality, 4) The overall effect of tillage and traffic on plant production and the environment (greenhouse gas emissions, N leaching). My PhD thesis from 2001 was on the influence of soil management and water regime on soil fragmentation and soil friability. I have continued to work in this field of research to get more detailed knowledge on effects of both basic soil properties (water content, soil type, organic matter) as well as soil management (tillage and traffic, crop rotation, fertilization). Recently, I have, in collaboration with agricultural engineers, focused more strongly on soil fragmentation in tillage in relation to development on new energy efficient and effective tillage tools. The work on root growth has mainly been concentrated on tillage and traffic (compaction) effects. Traditional and new non-invasive tomographic methods (PET/CT) have been a used to study both soil structure and root growth. The impact of cropping system (tillage, traffic, cover crop) on the environment has been studied in relation to nitrogen leaching, nitrous oxide emissions and carbon sequestration.