Vannlogging

Vannlogging (literally "waterlogging") refers to the condition in which soil becomes saturated with water to the point that air in the pore spaces is displaced, reducing oxygen availability for plant roots and soil organisms. The term is used in hydrology, soil science and agriculture to describe both transient saturation after heavy precipitation and long-term excess moisture from a high water table or poor drainage.

Causes of vannlogging include intense or prolonged rainfall, inadequate surface or subsurface drainage, over-irrigation, compacted soils with low permeability, and rising groundwater. Landscape position—such as low-lying areas, floodplains or depressions—also increases vulnerability.

Ecological and agricultural effects can be substantial. Oxygen deficiency impairs root respiration and nutrient uptake, often causing reduced crop yields, increased susceptibility to disease and root rot, and plant death. Waterlogged conditions alter soil chemistry, promoting anaerobic microbial processes that can produce methane and reduce certain nutrients. Soil structure may deteriorate through aggregate breakdown and compaction when wet soils are trafficked.

Management and mitigation strategies focus on improving drainage and reducing water input. Common measures include installation of surface drains or subsurface tile systems, raised beds and ridges, improving soil structure with organic matter to increase infiltration, altering crop choice and timing, and controlled irrigation. Land-use planning and wetland restoration also play roles where natural hydrology should be preserved. Monitoring soil moisture and groundwater levels aids in early detection and decision-making to limit impacts.