Soils can be compact, i.e., have a high dry bulk density, due to natural causes, land use change, or unintended soil management effects (e.g., soil compaction caused by vehicle traffic). Soil compaction decreases pore volume, connectivity, and continuity, adversely affecting many soil properties and soil conditions, which negatively impacts crop productivity and other soil functions. Crop growth is impeded in compact soils, amongst others, due to increased soil mechanical resistance for root growth resulting in decreased root elongation rates and reduced accessibility to water and nutrients, poor soil aeration causing oxygen limitation, and reduced water infiltration and storage capacity resulting in water stress. This chapter gives a brief overview of the causes and consequences of soil compaction, discusses how crop growth is affected in high bulk density soils, and outlines strategies to minimise and alleviate soil compaction.
